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• Speeding up inner-joins and subqueries while restricting row size and table membership

  - by hiffy

  I'm developing an rss feed reader that uses a bayesian filter to filter out boring blog posts. The Stream table is meant to act as a FIFO buffer from which the webapp will consume 'entries'. I use it to store the temporary relationship between entries, users and bayesian filter classifications. After a user marks an entry as read, it will be added to the metadata table (so that a user isn't presented with material they have already read), and deleted from the stream table. Every three minutes, a background process will repopulate the Stream table with new entries (i.e. whenever the daemon adds new entries after the checks the rss feeds for updates). Problem: The query I came up with is hella slow. More importantly, the Stream table only needs to hold one hundred unread entries at a time; it'll reduce duplication, make processing faster and give me some flexibility with how I display the entries. The query (takes about 9 seconds on 3600 items with no indexes): insert into stream(entry_id, user_id) select entries.id, subscriptions_users.user_id from entries inner join subscriptions_users on subscriptions_users.subscription_id = entries.subscription_id where subscriptions_users.user_id = 1 and entries.id not in (select entry_id from metadata where metadata.user_id = 1) and entries.id not in (select entry_id from stream where user_id = 1); The query explained: insert into stream all of the entries from a user's subscription list (subscriptions_users) that the user has not read (i.e. do not exist in metadata) and which do not already exist in the stream. Attempted solution: adding limit 100 to the end speeds up the query considerably, but upon repeated executions will keep on adding a different set of 100 entries that do not already exist in the table (with each successful query taking longer and longer). This is close but not quite what I wanted to do. Does anyone have any advice (nosql?) or know a more efficient way of composing the query?

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• How to approach parallel processing of messages?

  - by Dan

  I am redesigning the messaging system for my app to use intel threading building blocks and am stumped trying to decide between two possible approaches. Basically, I have a sequence of message objects and for each message type, a sequence of handlers. For each message object, I apply each handler registered for that message objects type. The sequential version would be something like this (pseudocode): for each message in message_sequence <- SEQUENTIAL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The first approach which I am considering processes the message objects in turn (sequentially) and applies the handlers concurrently. Pros: predictable ordering of messages (ie, we are guaranteed a FIFO processing order) (potentially) lower latency of processing each message Cons: more processing resources available than handlers for a single message type (bad parallelization) bad use of processor cache since message objects need to be copied for each handler to use large overhead for small handlers The pseudocode of this approach would be as follows: for each message in message_sequence <- SEQUENTIAL parallel_for each handler in (handler_table for message.type) apply handler to message <- PARALLEL The second approach is to process the messages in parallel and apply the handlers to each message sequentially. Pros: better use of processor cache (keeps the message object local to all handlers which will use it) small handlers don't impose as much overhead (as long as there are other handlers also to be run) more messages are expected than there are handlers, so the potential for parallelism is greater Cons: Unpredictable ordering - if message A is sent before message B, they may both be processed at the same time, or B may finish processing before all of A's handlers are finished (order is non-deterministic) The pseudocode is as follows: parallel_for each message in message_sequence <- PARALLEL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The second approach has more advantages than the first, but non-deterministic ordering is a big disadvantage.. Which approach would you choose and why? Are there any other approaches I should consider (besides the obvious third approach: parallel messages and parallel handlers, which has the disadvantages of both and no real redeeming factors as far as I can tell)? Thanks!

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• Which Queue implementation to use in Java?

  - by devoured elysium

  I need to use a FIFO structure in my application. It needs to have at most 5 elements. I'd like to have something easy to use (I don't care for concurrency) that implements the Collection interface. I've tried the LinkedList, that seems to come from Queue, but it doesn't seem to allow me to set it's maximum capacity. It feels as if I just want at max 5 elements but try to add 20, it will just keep increasing in size to fit it. I'd like something that'd work the following way: XQueue<Integer> queue = new XQueue<Integer>(5); //where 5 is the maximum number of elements I want in my queue. for (int i = 0; i < 10; ++i) { queue.offer(i); } for (int i = 0; i < 5; ++i) { System.out.println(queue.poll()); } That'd print: 5 6 7 8 9 Thanks

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• callbacks via objective-c selectors

  - by codemonkey

  I have a "BSjax" class that I wrote that lets me make async calls to our server to get json result sets, etc using the ASIHTTPRequest class. I set it up so that the BSjax class parses my server's json response, then passes control back to the calling view controller via this call: [[self delegate] performSelectorOnMainThread:@selector(bsRequestFinished:) withObject:self waitUntilDone:YES]; ... where "bsRequestFinished" is the callback method in the calling view controller. This all worked fine and well until I realized that some pages are going to need to make different types of requests... i.e. I'll want to do different types of things in that callback function depending on which type of request was made. To me it seems like being able to pass different callback function names to my BSjax class would be the cleanest fix... but I'm having trouble (and am not even sure if it's possible) to pass in a variable that holds the callback function name and then replace the call above with something like this: [[self delegate] performSelectorOnMainThread:@selector(self.variableCallbackFunctionName) withObject:self waitUntilDone:YES]; ... where "self.variableCallbackFunctionName" is set by the calling view controller when it calls BSjax to make a new request. Is this even possible? If so, advisable? If not, alternatives? EDIT: Note that whatever fix I arrive at will need to take into account the reality that this class is making async requests... so I need to make sure that the callback function processing is correctly tied to the specific requests... as I can't rely on FIFO processing sequence.

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• Need help with threads in a client/server

  - by nunos

  For college, I am developing a local relay chat. I have to program a chat server and client that will only work on sending messages on different terminal windows on the same computer with threads and fifos. The fifos part I am having no trouble, the threads part is the one that is giving me some headaches. The server has one thread for receiving commands from a fifo (used by all clients) and another thread for each client that is connected. For each client that is connected I need to know a certain information. Firstly, I was using global variables, which worked as longs as there was only one client connected, which is much of a chat, to chat alone. So, ideally I would have some data like: -nickname -name -email -etc... per client that is connected. However, I don't know how to do that. I could create a client_data[MAX_NUMBER_OF_THREADS] where client_data was a struct with everything I needed to have access to, but this would require to, in every communication between server and client to ask for the id of the client in the array client_data and that does not seem very pratical I could also instantiate a client_data immediately after creating the thread but it would only be available in that block, and that is not very pratical either. As you can see I am in need of a little guidance here. Any comment, piece of code or link to any relevant information is greatly appreciated. Thanks.

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• BackgroundWorker Help needed

  - by ChrisMuench

  I have code that does a web-service request. While doing this request I need a progress-bar to be moving independently. My problem is that I just need to say run a progress update every 1 or 2 seconds and check to see if progress of the request has been completed. NetBasisServicesSoapClient client = new NetBasisServicesSoapClient(); TransactionDetails[] transactions = new TransactionDetails[dataGridView1.Rows.Count - 1]; for (int i = 0; i < dataGridView1.Rows.Count - 1; i++) { transactions[i] = new TransactionDetails(); transactions[i].TransactionDate = (string)dataGridView1.Rows[i].Cells[2].Value; transactions[i].TransactionType = (string)dataGridView1.Rows[i].Cells[3].Value; transactions[i].Shares = (string)dataGridView1.Rows[i].Cells[4].Value; transactions[i].Pershare = (string)dataGridView1.Rows[i].Cells[5].Value; transactions[i].TotalAmount = (string)dataGridView1.Rows[i].Cells[6].Value; } CostbasisResult result = client.Costbasis(dataGridView1.Rows[0].Cells[0].Value.ToString(), dataGridView1.Rows[0].Cells[1].Value.ToString(), transactions, false, "", "", "FIFO", true); string result1 = ConvertStringArrayToString(result.Details);

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• How to hold a queue of messages and have a group of working threads without polling?

  - by Mark

  I have a workflow that I want to looks something like this: / Worker 1 \ =Request Channel= - [Holding Queue|||] - Worker 2 - =Response Channel= \ Worker 3 / That is: Requests come in and they enter a FIFO queue Identical workers then pick up tasks from the queue At any given time any worker may work only one task When a worker is free and the holding queue is non-empty the worker should immediately pick up another task When tasks are complete, a worker places the result on the Response Channel I know there are QueueChannels in Spring Integration, but these channels require polling (which seems suboptimal). In particular, if a worker can be busy, I'd like the worker to be busy. Also, I've considered avoiding the queue altogether and simply letting tasks round-robin to all workers, but it's preferable to have a single waiting line as some tasks may be accomplished faster than others. Furthermore, I'd like insight into how many jobs are remaining (which I can get from the queue) and the ability to cancel all or particular jobs. How can I implement this message queuing/work distribution pattern while avoiding a polling? Edit: It appears I'm looking for the Message Dispatcher pattern -- how can I implement this using Spring/Spring Integration?

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• Web site not responding

  - by Subhransu

  I have website working fine before. But now its not able to connect to the server(I believe that is the problem). But its strange that the message not able to connect to the server is not coming and its keep connecting... for infinite time. Here is the screenshot. Here are some of the useful details about the status of the server. Application starts when server wakes up are: cd /etc/init.d/ Application server running in my server : Traceroute: UPDATE: ps aux USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0.0 0.0 19204 744 ? Ss Aug07 0:01 /sbin/init root 2 0.0 0.0 0 0 ? S Aug07 0:00 [kthreadd] root 3 0.0 0.0 0 0 ? S Aug07 0:00 [migration/0] root 4 0.0 0.0 0 0 ? S Aug07 7:15 [ksoftirqd/0] root 5 0.0 0.0 0 0 ? S Aug07 0:00 [migration/0] root 6 0.0 0.0 0 0 ? S Aug07 0:00 [watchdog/0] root 7 0.0 0.0 0 0 ? S Aug07 0:05 [events/0] root 8 0.0 0.0 0 0 ? S Aug07 0:00 [cpuset] root 9 0.0 0.0 0 0 ? S Aug07 0:00 [khelper] root 10 0.0 0.0 0 0 ? S Aug07 0:00 [netns] root 11 0.0 0.0 0 0 ? S Aug07 0:00 [async/mgr] root 12 0.0 0.0 0 0 ? S Aug07 0:00 [pm] root 13 0.0 0.0 0 0 ? S Aug07 0:00 [sync_supers] root 14 0.0 0.0 0 0 ? S Aug07 0:00 [bdi-default] root 15 0.0 0.0 0 0 ? S Aug07 0:00 [kintegrityd/0] root 16 0.0 0.0 0 0 ? S Aug07 0:24 [kblockd/0] root 17 0.0 0.0 0 0 ? S Aug07 0:00 [kacpid] root 18 0.0 0.0 0 0 ? S Aug07 0:00 [kacpi_notify] root 19 0.0 0.0 0 0 ? S Aug07 0:00 [kacpi_hotplug] root 20 0.0 0.0 0 0 ? S Aug07 0:00 [ata/0] root 21 0.0 0.0 0 0 ? S Aug07 0:00 [ata_aux] root 22 0.0 0.0 0 0 ? S Aug07 0:00 [ksuspend_usbd] root 23 0.0 0.0 0 0 ? S Aug07 0:00 [khubd] root 24 0.0 0.0 0 0 ? S Aug07 0:00 [kseriod] root 25 0.0 0.0 0 0 ? S Aug07 0:00 [md/0] root 26 0.0 0.0 0 0 ? S Aug07 0:00 [md_misc/0] root 27 0.0 0.0 0 0 ? S Aug07 0:00 [khungtaskd] root 28 0.0 0.0 0 0 ? S Aug07 0:19 [kswapd0] root 29 0.0 0.0 0 0 ? SN Aug07 0:00 [ksmd] root 30 0.0 0.0 0 0 ? SN Aug07 1:36 [khugepaged] root 31 0.0 0.0 0 0 ? S Aug07 0:00 [aio/0] root 32 0.0 0.0 0 0 ? S Aug07 0:00 [crypto/0] root 37 0.0 0.0 0 0 ? S Aug07 0:00 [kthrotld/0] root 38 0.0 0.0 0 0 ? S Aug07 0:00 [pciehpd] root 40 0.0 0.0 0 0 ? S Aug07 0:00 [kpsmoused] root 41 0.0 0.0 0 0 ? S Aug07 0:00 [usbhid_resumer] root 71 0.0 0.0 0 0 ? S Aug07 0:00 [kstriped] root 203 0.0 0.0 0 0 ? S Aug07 0:00 [scsi_eh_0] root 206 0.0 0.0 0 0 ? S Aug07 0:00 [scsi_eh_1] root 213 0.0 0.0 0 0 ? S Aug07 0:00 [mpt_poll_0] root 214 0.0 0.0 0 0 ? S Aug07 0:00 [mpt/0] root 215 0.0 0.0 0 0 ? S Aug07 0:00 [scsi_eh_2] root 317 0.0 0.0 0 0 ? S Aug07 0:00 [kdmflush] root 319 0.0 0.0 0 0 ? S Aug07 0:00 [kdmflush] root 338 0.0 0.0 0 0 ? S Aug07 4:30 [jbd2/dm-0-8] root 339 0.0 0.0 0 0 ? S Aug07 0:00 [ext4-dio-unwrit] root 411 0.0 0.0 11060 224 ? S<s Aug07 0:00 /sbin/udevd -d root 591 0.0 0.0 0 0 ? S Aug07 0:00 [vmmemctl] root 732 0.0 0.0 0 0 ? S Aug07 0:00 [jbd2/sda1-8] root 733 0.0 0.0 0 0 ? S Aug07 0:00 [ext4-dio-unwrit] root 770 0.0 0.0 0 0 ? S Aug07 0:00 [kauditd] root 907 0.0 0.0 0 0 ? S Aug07 0:02 [flush-253:0] root 963 0.0 0.0 93180 528 ? S<sl Aug07 0:00 auditd root 979 0.0 0.0 248680 1132 ? Sl Aug07 0:04 /sbin/rsyslogd -i /var/run/syslogd.pid -c 4 dbus 991 0.0 0.0 31740 348 ? Ssl Aug07 0:00 dbus-daemon --system root 1023 0.0 0.0 64032 456 ? Ss Aug07 0:01 /usr/sbin/sshd root 1031 0.0 0.0 22076 592 ? Ss Aug07 0:00 xinetd -stayalive -pidfile /var/run/xinetd.pid root 1107 0.0 0.0 78652 744 ? Ss Aug07 0:01 /usr/libexec/postfix/master postfix 1116 0.0 0.0 78904 852 ? S Aug07 0:00 qmgr -l -t fifo -u qpidd 1129 0.0 0.0 234596 1488 ? Ssl Aug07 1:54 /usr/sbin/qpidd --data-dir /var/lib/qpidd --daemon root 1181 0.0 0.0 117176 532 ? Ss Aug07 0:04 crond root 1217 0.0 0.0 108152 412 ? S Aug07 0:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --socket=/var/lib/mysql/m mysql 1306 0.0 1.8 792636 72640 ? Sl Aug07 6:51 /usr/libexec/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --log- root 1334 0.0 0.1 739156 5520 ? Ssl Aug07 0:34 /usr/sbin/shibd -p /var/run/shibboleth/shibd.pid -f -w 30 root 1355 0.0 0.0 4048 272 tty2 Ss+ Aug07 0:00 /sbin/mingetty /dev/tty2 root 1357 0.0 0.0 4048 272 tty3 Ss+ Aug07 0:00 /sbin/mingetty /dev/tty3 root 1360 0.0 0.0 12336 264 ? S< Aug07 0:00 /sbin/udevd -d root 1361 0.0 0.0 12336 240 ? S< Aug07 0:00 /sbin/udevd -d root 1362 0.0 0.0 4048 272 tty4 Ss+ Aug07 0:00 /sbin/mingetty /dev/tty4 root 1364 0.0 0.0 4048 272 tty5 Ss+ Aug07 0:00 /sbin/mingetty /dev/tty5 root 1366 0.0 0.0 4048 272 tty6 Ss+ Aug07 0:00 /sbin/mingetty /dev/tty6 root 1394 0.0 0.0 574892 436 ? Sl Aug07 0:00 /usr/sbin/console-kit-daemon --no-daemon root 1495 0.0 0.0 4048 264 tty1 Ss+ Aug07 0:00 /sbin/mingetty /dev/tty1 root 7665 0.0 0.1 296304 6244 ? Ss Aug16 2:33 /usr/sbin/httpd apache 10298 0.0 0.2 457756 10472 ? Sl Sep07 3:35 /usr/sbin/httpd apache 11684 0.0 0.5 465352 20708 ? Sl Sep12 0:02 /usr/sbin/httpd apache 14570 0.0 0.7 475592 30628 ? Sl Sep12 0:02 /usr/sbin/httpd apache 14877 0.0 0.5 467868 22696 ? Sl Sep12 0:01 /usr/sbin/httpd apache 15128 0.0 0.4 464628 19096 ? Sl Sep12 0:01 /usr/sbin/httpd apache 15151 0.0 0.4 464624 18980 ? Sl Sep12 0:01 /usr/sbin/httpd apache 15169 0.0 0.6 470268 24636 ? Sl Sep12 0:01 /usr/sbin/httpd apache 15238 0.0 0.4 464628 19108 ? Sl Sep12 0:01 /usr/sbin/httpd apache 15266 0.0 0.4 464624 18920 ? Sl Sep12 0:02 /usr/sbin/httpd apache 15312 0.0 0.4 464624 18724 ? Sl Sep12 0:01 /usr/sbin/httpd apache 15427 0.0 0.6 470268 24644 ? Sl Sep12 0:00 /usr/sbin/httpd apache 15814 0.0 0.4 464884 19296 ? Sl 00:14 0:01 /usr/sbin/httpd apache 15830 0.0 0.4 464628 19028 ? Sl 00:24 0:00 /usr/sbin/httpd apache 15859 0.0 0.7 475524 30320 ? Sl 00:31 0:00 /usr/sbin/httpd apache 15897 0.0 0.6 471876 26056 ? Sl 00:42 0:00 /usr/sbin/httpd apache 15926 0.0 0.4 464884 18936 ? Sl 00:46 0:01 /usr/sbin/httpd apache 15970 0.0 0.6 470268 24216 ? Sl 00:57 0:00 /usr/sbin/httpd apache 16010 0.0 0.4 464884 18912 ? Sl 01:04 0:00 /usr/sbin/httpd apache 16023 0.0 0.3 457756 12300 ? Sl 01:05 0:02 /usr/sbin/httpd apache 16176 0.0 0.4 464624 18568 ? Sl 02:01 0:01 /usr/sbin/httpd apache 16213 0.0 0.4 464624 18900 ? Sl 02:22 0:01 /usr/sbin/httpd apache 16240 0.0 0.4 464884 18828 ? Sl 02:35 0:00 /usr/sbin/httpd root 16313 0.0 0.0 19372 968 ? Ss 03:01 0:00 /usr/sbin/anacron -s apache 16361 0.0 0.4 464624 18572 ? Sl 03:17 0:00 /usr/sbin/httpd apache 16364 0.0 0.4 464884 19284 ? Sl 03:19 0:01 /usr/sbin/httpd root 16421 0.0 0.0 9180 1300 ? SN 03:37 0:00 /bin/bash /usr/bin/run-parts /etc/cron.daily root 16426 0.0 0.0 9312 1404 ? SN 03:37 0:00 /bin/bash /etc/cron.daily/backupdb root 16427 0.0 0.0 9064 820 ? SN 03:37 0:00 awk -v progname /etc/cron.daily/backupdb progname {????? print progname ":\n" root 16434 0.0 0.0 50776 2420 ? SN 03:37 0:00 mysqldump --opt --quote-names -u root -px xxx inamiriziv_dokeos_user personal_a root 16435 0.0 0.0 4280 536 ? SN 03:37 0:00 gzip --rsyncable apache 16484 0.0 0.2 457584 11432 ? Sl 03:55 0:04 /usr/sbin/httpd apache 16492 0.0 0.4 464884 19320 ? Sl 03:58 0:02 /usr/sbin/httpd apache 16496 0.0 0.4 464624 18704 ? Sl 04:00 0:02 /usr/sbin/httpd apache 16529 0.0 0.6 470268 24608 ? Sl 04:06 0:02 /usr/sbin/httpd apache 16533 0.0 0.4 464624 18532 ? Sl 04:10 0:00 /usr/sbin/httpd apache 16536 0.0 0.4 464884 18908 ? Sl 04:10 0:00 /usr/sbin/httpd apache 16556 0.0 0.4 464884 18924 ? Sl 04:18 0:02 /usr/sbin/httpd apache 16563 0.0 0.3 457756 12384 ? Sl 04:19 0:07 /usr/sbin/httpd apache 16598 0.0 0.3 457756 12344 ? Sl 04:28 0:02 /usr/sbin/httpd apache 16633 0.0 0.4 464624 18492 ? Sl 04:41 0:00 /usr/sbin/httpd apache 16637 0.0 0.6 470268 24300 ? Sl 04:41 0:02 /usr/sbin/httpd apache 16654 0.0 0.3 457756 12296 ? Sl 04:47 0:02 /usr/sbin/httpd apache 16665 0.0 0.6 470268 24308 ? Sl 04:50 0:03 /usr/sbin/httpd apache 16738 0.0 0.6 470268 24312 ? Sl 05:10 0:02 /usr/sbin/httpd apache 17388 0.0 0.2 457584 11440 ? Sl 08:56 0:01 /usr/sbin/httpd apache 17391 0.0 0.3 457756 12296 ? Sl 08:57 0:00 /usr/sbin/httpd apache 17397 0.0 0.3 457756 12312 ? Sl 08:59 0:00 /usr/sbin/httpd apache 17401 0.0 0.3 457756 12284 ? Sl 09:00 0:00 /usr/sbin/httpd apache 17420 0.0 0.2 457584 11436 ? Sl 09:04 0:01 /usr/sbin/httpd apache 17426 0.0 0.3 457756 12324 ? Sl 09:07 0:01 /usr/sbin/httpd apache 17431 0.0 0.3 457756 12276 ? Sl 09:08 0:03 /usr/sbin/httpd apache 17434 0.0 0.3 457756 12308 ? Sl 09:08 0:00 /usr/sbin/httpd apache 17437 0.0 0.2 457584 11440 ? Sl 09:09 0:01 /usr/sbin/httpd apache 17442 0.0 0.2 457584 11436 ? Sl 09:10 0:01 /usr/sbin/httpd apache 17445 0.0 0.3 457756 12328 ? Sl 09:11 0:01 /usr/sbin/httpd apache 17449 0.0 0.3 457756 12292 ? Sl 09:12 0:01 /usr/sbin/httpd apache 17454 0.0 0.2 457584 11444 ? Sl 09:15 0:01 /usr/sbin/httpd apache 17457 0.0 0.2 457584 11436 ? Sl 09:15 0:01 /usr/sbin/httpd apache 17461 0.0 0.3 457756 12304 ? Sl 09:16 0:01 /usr/sbin/httpd apache 17465 0.0 0.2 457584 11444 ? Sl 09:18 0:01 /usr/sbin/httpd apache 17468 0.0 0.2 457584 11436 ? Sl 09:18 0:01 /usr/sbin/httpd apache 17473 0.0 0.4 464884 18940 ? Sl 09:19 0:00 /usr/sbin/httpd apache 17476 0.0 0.4 464628 18736 ? Sl 09:20 0:00 /usr/sbin/httpd apache 17479 0.0 0.2 457584 11440 ? Sl 09:20 0:01 /usr/sbin/httpd apache 17483 0.0 0.2 457584 11416 ? Sl 09:21 0:00 /usr/sbin/httpd apache 17486 0.0 0.3 457756 12296 ? Sl 09:21 0:01 /usr/sbin/httpd apache 17489 0.0 0.4 464884 18928 ? Sl 09:21 0:00 /usr/sbin/httpd apache 17492 0.0 0.2 457584 11260 ? Sl 09:22 0:00 /usr/sbin/httpd apache 17496 0.0 0.3 457756 12372 ? Sl 09:22 0:01 /usr/sbin/httpd apache 17500 0.0 0.2 457584 11428 ? Sl 09:23 0:00 /usr/sbin/httpd apache 17504 0.0 0.2 457584 11432 ? Sl 09:25 0:00 /usr/sbin/httpd apache 17509 0.0 0.3 457756 12336 ? Sl 09:27 0:01 /usr/sbin/httpd apache 17513 0.0 0.2 457584 11436 ? Sl 09:29 0:01 /usr/sbin/httpd apache 17517 0.0 0.2 457584 11448 ? Sl 09:31 0:00 /usr/sbin/httpd apache 17520 0.0 0.3 457584 12128 ? Sl 09:32 0:00 /usr/sbin/httpd apache 17525 0.0 0.4 464884 18960 ? Sl 09:34 0:00 /usr/sbin/httpd apache 17529 0.0 0.2 457584 11420 ? Sl 09:36 0:00 /usr/sbin/httpd apache 17533 0.0 0.2 457584 11436 ? Sl 09:38 0:00 /usr/sbin/httpd apache 17537 0.0 0.2 457584 11436 ? Sl 09:38 0:00 /usr/sbin/httpd apache 17542 0.0 0.4 464884 18840 ? Sl 09:40 0:00 /usr/sbin/httpd apache 17546 0.0 0.3 457756 12320 ? Sl 09:41 0:00 /usr/sbin/httpd apache 17550 0.0 0.2 457584 11440 ? Sl 09:42 0:00 /usr/sbin/httpd apache 17554 0.0 0.2 457584 11436 ? Sl 09:43 0:00 /usr/sbin/httpd apache 17557 0.0 0.2 457584 11436 ? Sl 09:44 0:00 /usr/sbin/httpd apache 17560 0.0 0.2 457584 11428 ? Sl 09:44 0:01 /usr/sbin/httpd apache 17568 0.0 0.4 464884 18824 ? Sl 09:48 0:00 /usr/sbin/httpd apache 17572 0.0 0.2 457584 11428 ? Sl 09:48 0:00 /usr/sbin/httpd apache 17575 0.0 0.2 457584 11428 ? Sl 09:48 0:01 /usr/sbin/httpd apache 17583 0.0 0.2 457584 11432 ? Sl 09:50 0:00 /usr/sbin/httpd apache 17586 0.0 0.3 457756 12264 ? Sl 09:50 0:00 /usr/sbin/httpd apache 17589 0.0 0.2 457584 11420 ? Sl 09:51 0:00 /usr/sbin/httpd apache 17597 0.0 0.2 457584 11420 ? Sl 09:53 0:02 /usr/sbin/httpd apache 17600 0.0 0.3 457756 12376 ? Sl 09:54 0:00 /usr/sbin/httpd apache 17604 0.0 0.2 457584 11436 ? Sl 09:55 0:00 /usr/sbin/httpd apache 17610 0.0 0.2 457584 11420 ? Sl 09:59 0:00 /usr/sbin/httpd apache 17615 0.0 0.2 457584 11424 ? Sl 10:00 0:00 /usr/sbin/httpd apache 17618 0.0 0.4 464884 19288 ? Sl 10:00 0:00 /usr/sbin/httpd apache 17635 0.0 0.2 457584 11416 ? Sl 10:01 0:00 /usr/sbin/httpd apache 17639 0.0 0.2 457584 11440 ? Sl 10:02 0:00 /usr/sbin/httpd apache 17643 0.0 0.2 457584 11448 ? Sl 10:03 0:00 /usr/sbin/httpd apache 17648 0.0 0.4 464884 18868 ? Sl 10:06 0:00 /usr/sbin/httpd apache 17651 0.0 0.2 457584 11416 ? Sl 10:07 0:00 /usr/sbin/httpd apache 17655 0.0 0.3 457756 12268 ? Sl 10:08 0:01 /usr/sbin/httpd apache 17658 0.0 0.2 457584 11440 ? Sl 10:08 0:00 /usr/sbin/httpd apache 17663 0.0 0.3 457756 12292 ? Sl 10:11 0:00 /usr/sbin/httpd apache 17666 0.0 0.2 457584 11432 ? Sl 10:11 0:00 /usr/sbin/httpd apache 17672 0.0 0.2 457584 11428 ? Sl 10:14 0:00 /usr/sbin/httpd apache 17676 0.0 0.2 457584 11424 ? Sl 10:16 0:00 /usr/sbin/httpd apache 17680 0.0 0.4 464884 18884 ? Sl 10:16 0:00 /usr/sbin/httpd apache 17683 0.0 0.2 457584 11420 ? Sl 10:19 0:00 /usr/sbin/httpd apache 17689 0.0 0.2 457584 11424 ? Sl 10:23 0:00 /usr/sbin/httpd apache 17692 0.0 0.2 457584 11428 ? Sl 10:23 0:00 /usr/sbin/httpd apache 17696 0.0 0.3 457584 11980 ? Sl 10:25 0:00 /usr/sbin/httpd apache 17699 0.0 0.2 457584 11436 ? Sl 10:25 0:00 /usr/sbin/httpd apache 17704 0.0 0.2 457584 11232 ? Sl 10:27 0:00 /usr/sbin/httpd apache 17711 0.0 0.2 457584 11412 ? Sl 10:30 0:01 /usr/sbin/httpd postfix 17714 0.0 0.0 78732 3216 ? S 10:30 0:00 pickup -l -t fifo -u apache 17715 0.0 0.2 457584 11436 ? Sl 10:30 0:00 /usr/sbin/httpd apache 17718 0.0 0.2 457584 11428 ? Sl 10:31 0:00 /usr/sbin/httpd apache 17726 0.0 0.2 457584 11420 ? Sl 10:36 0:00 /usr/sbin/httpd apache 17731 0.0 0.2 457584 11168 ? Sl 10:37 0:00 /usr/sbin/httpd apache 17734 0.0 0.4 464884 18796 ? Sl 10:37 0:00 /usr/sbin/httpd apache 17743 0.0 0.2 457584 11220 ? Sl 10:43 0:00 /usr/sbin/httpd apache 17746 0.0 0.2 457584 11172 ? Sl 10:44 0:00 /usr/sbin/httpd apache 17750 0.0 0.3 457756 12288 ? Sl 10:44 0:00 /usr/sbin/httpd apache 17753 0.0 0.2 457584 11220 ? Sl 10:45 0:00 /usr/sbin/httpd apache 17756 0.0 0.2 457584 11424 ? Sl 10:46 0:00 /usr/sbin/httpd apache 17763 0.0 0.3 457756 12204 ? Sl 10:51 0:00 /usr/sbin/httpd apache 17766 0.0 0.2 457584 11428 ? Sl 10:51 0:00 /usr/sbin/httpd apache 17771 0.0 0.2 457584 11180 ? Sl 10:54 0:00 /usr/sbin/httpd apache 17774 0.0 0.2 457584 11416 ? Sl 10:54 0:00 /usr/sbin/httpd apache 17779 0.0 0.2 457584 11428 ? Sl 10:58 0:00 /usr/sbin/httpd apache 17784 0.0 0.2 457584 11380 ? Sl 11:00 0:00 /usr/sbin/httpd apache 17805 0.0 0.2 457584 11380 ? Sl 11:05 0:00 /usr/sbin/httpd apache 17818 0.0 0.2 457584 11156 ? Sl 11:11 0:00 /usr/sbin/httpd apache 17823 0.0 0.2 457584 11416 ? Sl 11:12 0:00 /usr/sbin/httpd apache 17827 0.0 0.2 457584 11412 ? Sl 11:13 0:00 /usr/sbin/httpd apache 17831 0.0 0.2 457584 11132 ? Sl 11:13 0:00 /usr/sbin/httpd root 17835 0.0 0.0 97780 3792 ? S 11:14 0:00 sshd: smaity [priv] smaity 17839 0.0 0.0 97780 1748 ? S 11:15 0:00 sshd: smaity@pts/0 smaity 17840 0.0 0.0 108288 1928 pts/0 Ss 11:15 0:00 -bash apache 17858 0.0 0.4 464884 18856 ? Sl 11:16 0:00 /usr/sbin/httpd apache 17862 0.0 0.3 457584 11904 ? Sl 11:17 0:00 /usr/sbin/httpd apache 17866 0.0 0.2 457584 11212 ? Sl 11:19 0:00 /usr/sbin/httpd apache 17871 0.0 0.2 457584 11144 ? Sl 11:20 0:00 /usr/sbin/httpd apache 17875 0.0 0.2 457584 11416 ? Sl 11:23 0:00 /usr/sbin/httpd apache 17880 0.0 0.2 457584 11408 ? Sl 11:23 0:00 /usr/sbin/httpd apache 17883 0.0 0.2 457584 11412 ? Sl 11:24 0:00 /usr/sbin/httpd apache 17888 0.0 0.2 457584 11412 ? Sl 11:25 0:00 /usr/sbin/httpd apache 17891 0.0 0.2 457584 11140 ? Sl 11:26 0:00 /usr/sbin/httpd apache 17899 0.0 0.2 457584 10984 ? Sl 11:32 0:00 /usr/sbin/httpd apache 17902 0.0 0.2 457584 11680 ? Sl 11:33 0:00 /usr/sbin/httpd apache 17906 0.0 0.2 457584 10980 ? Sl 11:33 0:00 /usr/sbin/httpd Output of wget http://mydomain.com/ --2012-09-13 13:35:17-- http://mydomain.com/ Resolving mydomain.com... 127.0.0.1 Connecting to mydomain.com|127.0.0.1|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 45 [text/html] Saving to: “index.html” 0% [ ] 0 --.-K/s in 0s Cannot write to “index.html” (No space left on device). UPDATE3: output of df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_inamivm-lv_root 18G 17G 0 100% / tmpfs 1.9G 0 1.9G 0% /dev/shm /dev/sda1 485M 71M 389M 16% /boot output of wget -O /dev/null http://127.0.0.1/ --2012-09-13 13:47:49-- http://127.0.0.1/ Connecting to 127.0.0.1:80... connected. HTTP request sent, awaiting response... 200 OK Length: 45 [text/html] Saving to: “/dev/null” 100%[======================================================================================================>] 45 --.-K/s in 0s 2012-09-13 13:47:54 (8.57 MB/s) - “/dev/null” saved [45/45]

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• Stack-based keyboard delay using Logitech MX3100 keyboard

  - by Mark S. Rasmussen

  I've been using a Logitech Cordless Desktop MX3100 keyboard for quite a while. I've never really had any problems, except for the occasional typo. I noticed however that I tended make the typo "Laod" instead of "Load", quite a bit more often than any other typos. As it started to get on my nerves, I decided to do some testing. What I found out was than when I write lowercase "load", I'd never make the typo. All uppercase, or just uppercase L, I'd make the typo quite often. My actual (very scientific) testing is probably best described by showing the output: moatmoatmoat MoatMoatMoat loatloatloat LaotLaotLaot loafloafloaf LaofLaofLaof hoathoathoat HoatHoatHoat hoadhoadhoad HoadHoadHoad lortlortlort LrotLrotLrot What i found out was that whenever shift was depressed, typing an uppercase "L" would induce a significant lag if the next character was an "o", compared to the lag of the any other key: High "o" lag: LoLoLoLoLoLo No "a" lag: LaLaLaLaLaLa No lag for neither "o" nor "a": lolololololo lalalalalala By realizing this I regained a slight bit of sanity as I knew I wasn't coming down with a case of Parkinsons. I was actually typing correctly, the lag just interpreted it wrongly. Now, what really bugs me is that I can't fathom how this is occurring. What I'm actually typing, in physical order, is this: L - o - a - d, and yet, the "a" is output before the "o", even though "o" was pressed before "a". So while the keyboard is processing the "Lo" combo, the "a" gets prioritized and is inserted before the "o" is done processing, resulting in Laod instead of Load. And this only happens when typing "Lo", not when typing lowercase "lo". This problem could stem from the keyboard hardware, the receiver hardware or the keyboard software driver. No matter the fault location however, I can't imagine how this could be implemented as anything but a FIFO queue. A general delay, sure, I could live with that, albeit I'd be irritated. But a lag affecting different keys differently, and even resulting in unpredictable outcome - that just doesn't make any sense. I've solved the problem by just switching to a wired keyboard. I just can't shake it off me though; what kind of bug/error/scenario would result in a case like this? Edit: It's been suggested that I stop drinking Red Bull and stick to water instead. While that may actually help solve the issue, I'm really not looking for a solution as such. I'm more interested in an explanation of how this could happen, as I can't imagine any viable technical solution that could result in this behavior.

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• Hylafax / Capi4hylafax: faxgetty does not recognize number of lines

  - by Wrikken

  We've got a T.30 card, 30 working lines on it, but for some reason, if I add more then 30 faxes in the queue at any time (and we're busy enough at peak times that this happens a lot), faxgetty sends faxes to non-existent lines and they appear in the error queue as a 'busy' signal on the line, which results in a lot of failed faxes because the counter of max 3 tries increases rapidly. This is using faxgetty (USE_FAXGETTY="y" in /etc/default/hylafax). I've inherited this thing, so I'm not entirely sure how faxgetty is supposed to know the number of lines. However, if I alter the script to faxmodem (USE_FAXGETTY="n" in /etc/default/hylafax and manually enabling 30 modems), this behavior goes away (new faxes 'wait' for a line to be available before trying to send, so each try / fail is a valid one on a working line, majorly descreasing the amount of failed faxes. However, when researching this almost anyone talks about faxgetty being the preferred, more robust, method, and on top of that for some unexplained reason all FIFO's disappeared for some reason after several errorless hours with faxmodem, forcing a hylafax restart using faxgetty until we figured out why this faxmodem solution failed (which is another question, and somewhat out of scope here). Environment: Debian 2.6.26-2-amd64 capi4hylafax 1:01.03.00.99.svn.300-12 hylafax-client 2:4.4.4-10.1 hylafax-server 2:4.4.4-10.1 Config --hfaxd.conf-- LogFacility: daemon ServerTracing: 0x1ff --hyla.conf-- Host: localhost Verbose: No VRes: 196 TimeZone: local DialRules: "/etc/hylafax/dialrules.europe" --/etc/hylafax/config -- InternationalPrefix: 00 LongDistancePrefix: 0 AreaCode: 99999 CountryCode: 31 DialStringRules: "etc/dialrules.europe" ModemGroup: any:faxCAPI SendFaxCmd: "/usr/bin/wrapc2faxsend" --/etc/hylafax/config.faxCAPI -- SpoolDir: /var/spool/hylafax FaxRcvdCmd: /var/spool/hylafax/bin/faxrcvd PollRcvdCmd: /var/spool/hylafax/bin/pollrcvd FaxReceiveUser: uucp FaxReceiveGroup: dialout LogFile: /var/spool/hylafax/log/capi4hylafax #no, checking this log did not yield anything interesting LogTraceLevel: 4 LogFileMode: 0600 ModemGroup: any:faxCAPI #repeats of faxCAPI2 = faxCAPI30, with of course another devicename/local ident: { HylafaxDeviceName: faxCAPI RecvFileMode: 0600 FAXNumber: ****redacted**** LocalIdentifier: ****some-ident-per-device*** MaxConcurrentRecvs: 0 OutgoingController: 1 OutgoingMSN: SuppressMSN: 0 NumberPrefix: NumberPlusReplacer: "00" UseISDNFaxService: 0 RingingDuration: 0 { Controller: 1 AcceptSpeech: 0 UseDDI: 0 DDIOffset: DDILength: 0 IncomingDDIs: IncomingMSNs: AcceptGlobalCall: 1 } } So in short: How does faxgetty determine the number of lines available? (the man page isn't terribly revealing, and I can't find an appropriate setting in hylafax-config. And how can I get a capi4hylafax/hylafax setup which queues more faxes then lines are available correctly without immediately incrementing the fail count? We will not be receiving any faxes on this machine b.t.w. As I said, I've inherited this thing, so if there are important configuration options I'm not including, please let me know.

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• Where is all the memory being consumed?

  - by Mark L

  Hello, I have a Dell R300 Ubuntu 9.10 box with 4GB of memory. All I'm running on there is haproxy, nagios and postfix yet there is ~2.7GB of memory being consumed. I've run ps and I can't get the sums to add up. Could anyone shed any light on where all the memory is being used? Cheers, Mark $ sudo free -m total used free shared buffers cached Mem: 3957 2746 1211 0 169 2320 -/+ buffers/cache: 256 3701 Swap: 6212 0 6212 Sorry for pasting all of ps' output but I'm keen to get to the bottom of this. $ sudo ps aux [sudo] password for mark: USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0.0 0.0 19320 1656 ? Ss May20 0:05 /sbin/init root 2 0.0 0.0 0 0 ? S< May20 0:00 [kthreadd] root 3 0.0 0.0 0 0 ? S< May20 0:00 [migration/0] root 4 0.0 0.0 0 0 ? S< May20 0:16 [ksoftirqd/0] root 5 0.0 0.0 0 0 ? S< May20 0:00 [watchdog/0] root 6 0.0 0.0 0 0 ? S< May20 0:03 [migration/1] root 7 0.0 0.0 0 0 ? S< May20 3:10 [ksoftirqd/1] root 8 0.0 0.0 0 0 ? S< May20 0:00 [watchdog/1] root 9 0.0 0.0 0 0 ? S< May20 0:00 [migration/2] root 10 0.0 0.0 0 0 ? S< May20 0:19 [ksoftirqd/2] root 11 0.0 0.0 0 0 ? S< May20 0:00 [watchdog/2] root 12 0.0 0.0 0 0 ? S< May20 0:01 [migration/3] root 13 0.0 0.0 0 0 ? S< May20 0:41 [ksoftirqd/3] root 14 0.0 0.0 0 0 ? S< May20 0:00 [watchdog/3] root 15 0.0 0.0 0 0 ? S< May20 0:03 [events/0] root 16 0.0 0.0 0 0 ? S< May20 0:10 [events/1] root 17 0.0 0.0 0 0 ? S< May20 0:08 [events/2] root 18 0.0 0.0 0 0 ? S< May20 0:08 [events/3] root 19 0.0 0.0 0 0 ? S< May20 0:00 [cpuset] root 20 0.0 0.0 0 0 ? S< May20 0:00 [khelper] root 21 0.0 0.0 0 0 ? S< May20 0:00 [netns] root 22 0.0 0.0 0 0 ? S< May20 0:00 [async/mgr] root 23 0.0 0.0 0 0 ? S< May20 0:00 [kintegrityd/0] root 24 0.0 0.0 0 0 ? S< May20 0:00 [kintegrityd/1] root 25 0.0 0.0 0 0 ? S< May20 0:00 [kintegrityd/2] root 26 0.0 0.0 0 0 ? S< May20 0:00 [kintegrityd/3] root 27 0.0 0.0 0 0 ? S< May20 0:00 [kblockd/0] root 28 0.0 0.0 0 0 ? S< May20 0:01 [kblockd/1] root 29 0.0 0.0 0 0 ? S< May20 0:04 [kblockd/2] root 30 0.0 0.0 0 0 ? S< May20 0:02 [kblockd/3] root 31 0.0 0.0 0 0 ? S< May20 0:00 [kacpid] root 32 0.0 0.0 0 0 ? S< May20 0:00 [kacpi_notify] root 33 0.0 0.0 0 0 ? S< May20 0:00 [kacpi_hotplug] root 34 0.0 0.0 0 0 ? S< May20 0:00 [ata/0] root 35 0.0 0.0 0 0 ? S< May20 0:00 [ata/1] root 36 0.0 0.0 0 0 ? S< May20 0:00 [ata/2] root 37 0.0 0.0 0 0 ? S< May20 0:00 [ata/3] root 38 0.0 0.0 0 0 ? S< May20 0:00 [ata_aux] root 39 0.0 0.0 0 0 ? S< May20 0:00 [ksuspend_usbd] root 40 0.0 0.0 0 0 ? S< May20 0:00 [khubd] root 41 0.0 0.0 0 0 ? S< May20 0:00 [kseriod] root 42 0.0 0.0 0 0 ? S< May20 0:00 [kmmcd] root 43 0.0 0.0 0 0 ? S< May20 0:00 [bluetooth] root 44 0.0 0.0 0 0 ? S May20 0:00 [khungtaskd] root 45 0.0 0.0 0 0 ? S May20 0:00 [pdflush] root 46 0.0 0.0 0 0 ? S May20 0:09 [pdflush] root 47 0.0 0.0 0 0 ? S< May20 0:00 [kswapd0] root 48 0.0 0.0 0 0 ? S< May20 0:00 [aio/0] root 49 0.0 0.0 0 0 ? S< May20 0:00 [aio/1] root 50 0.0 0.0 0 0 ? S< May20 0:00 [aio/2] root 51 0.0 0.0 0 0 ? S< May20 0:00 [aio/3] root 52 0.0 0.0 0 0 ? S< May20 0:00 [ecryptfs-kthrea] root 53 0.0 0.0 0 0 ? S< May20 0:00 [crypto/0] root 54 0.0 0.0 0 0 ? S< May20 0:00 [crypto/1] root 55 0.0 0.0 0 0 ? S< May20 0:00 [crypto/2] root 56 0.0 0.0 0 0 ? S< May20 0:00 [crypto/3] root 70 0.0 0.0 0 0 ? S< May20 0:00 [scsi_eh_0] root 71 0.0 0.0 0 0 ? S< May20 0:00 [scsi_eh_1] root 74 0.0 0.0 0 0 ? S< May20 0:00 [scsi_eh_2] root 75 0.0 0.0 0 0 ? S< May20 0:00 [scsi_eh_3] root 82 0.0 0.0 0 0 ? S< May20 0:00 [kstriped] root 83 0.0 0.0 0 0 ? S< May20 0:00 [kmpathd/0] root 84 0.0 0.0 0 0 ? S< May20 0:00 [kmpathd/1] root 85 0.0 0.0 0 0 ? S< May20 0:00 [kmpathd/2] root 86 0.0 0.0 0 0 ? S< May20 0:00 [kmpathd/3] root 87 0.0 0.0 0 0 ? S< May20 0:00 [kmpath_handlerd] root 88 0.0 0.0 0 0 ? S< May20 0:00 [ksnapd] root 89 0.0 0.0 0 0 ? S< May20 0:00 [kondemand/0] root 90 0.0 0.0 0 0 ? S< May20 0:00 [kondemand/1] root 91 0.0 0.0 0 0 ? S< May20 0:00 [kondemand/2] root 92 0.0 0.0 0 0 ? S< May20 0:00 [kondemand/3] root 93 0.0 0.0 0 0 ? S< May20 0:00 [kconservative/0] root 94 0.0 0.0 0 0 ? S< May20 0:00 [kconservative/1] root 95 0.0 0.0 0 0 ? S< May20 0:00 [kconservative/2] root 96 0.0 0.0 0 0 ? S< May20 0:00 [kconservative/3] root 97 0.0 0.0 0 0 ? S< May20 0:00 [krfcommd] root 315 0.0 0.0 0 0 ? S< May20 0:09 [mpt_poll_0] root 317 0.0 0.0 0 0 ? S< May20 0:00 [mpt/0] root 547 0.0 0.0 0 0 ? S< May20 0:00 [scsi_eh_4] root 587 0.0 0.0 0 0 ? S< May20 0:11 [kjournald2] root 636 0.0 0.0 12748 860 ? S May20 0:00 upstart-udev-bridge --daemon root 657 0.0 0.0 17064 924 ? S<s May20 0:00 udevd --daemon root 666 0.0 0.0 8192 612 ? Ss May20 0:00 dd bs=1 if=/proc/kmsg of=/var/run/rsyslog/kmsg root 774 0.0 0.0 17060 888 ? S< May20 0:00 udevd --daemon root 775 0.0 0.0 17060 888 ? S< May20 0:00 udevd --daemon syslog 825 0.0 0.0 191696 1988 ? Sl May20 0:31 rsyslogd -c4 root 839 0.0 0.0 0 0 ? S< May20 0:00 [edac-poller] root 870 0.0 0.0 0 0 ? S< May20 0:00 [kpsmoused] root 1006 0.0 0.0 5988 604 tty4 Ss+ May20 0:00 /sbin/getty -8 38400 tty4 root 1008 0.0 0.0 5988 604 tty5 Ss+ May20 0:00 /sbin/getty -8 38400 tty5 root 1015 0.0 0.0 5988 604 tty2 Ss+ May20 0:00 /sbin/getty -8 38400 tty2 root 1016 0.0 0.0 5988 608 tty3 Ss+ May20 0:00 /sbin/getty -8 38400 tty3 root 1018 0.0 0.0 5988 604 tty6 Ss+ May20 0:00 /sbin/getty -8 38400 tty6 daemon 1025 0.0 0.0 16512 472 ? Ss May20 0:00 atd root 1026 0.0 0.0 18708 1000 ? Ss May20 0:03 cron root 1052 0.0 0.0 49072 1252 ? Ss May20 0:25 /usr/sbin/sshd root 1084 0.0 0.0 5988 604 tty1 Ss+ May20 0:00 /sbin/getty -8 38400 tty1 root 6320 0.0 0.0 19440 956 ? Ss May21 0:00 /usr/sbin/xinetd -pidfile /var/run/xinetd.pid -stayalive -inetd_compat -inetd_ipv6 nagios 8197 0.0 0.0 27452 1696 ? SNs May21 2:57 /usr/sbin/nagios3 -d /etc/nagios3/nagios.cfg root 10882 0.1 0.0 70280 3104 ? Ss 10:30 0:00 sshd: mark [priv] mark 10934 0.0 0.0 70432 1776 ? S 10:30 0:00 sshd: mark@pts/0 mark 10935 1.4 0.1 21572 4336 pts/0 Ss 10:30 0:00 -bash root 10953 1.0 0.0 15164 1136 pts/0 R+ 10:30 0:00 ps aux haproxy 12738 0.0 0.0 17208 992 ? Ss Jun08 0:49 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg root 23953 0.0 0.0 37012 2192 ? Ss Jun04 0:03 /usr/lib/postfix/master postfix 23955 0.0 0.0 39232 2356 ? S Jun04 0:00 qmgr -l -t fifo -u postfix 32603 0.0 0.0 39072 2132 ? S 09:05 0:00 pickup -l -t fifo -u -c Here's meminfo: $ cat /proc/meminfo MemTotal: 4052852 kB MemFree: 1240488 kB Buffers: 173172 kB Cached: 2376420 kB SwapCached: 0 kB Active: 1479288 kB Inactive: 1081876 kB Active(anon): 11792 kB Inactive(anon): 0 kB Active(file): 1467496 kB Inactive(file): 1081876 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 6361700 kB SwapFree: 6361700 kB Dirty: 44 kB Writeback: 0 kB AnonPages: 11568 kB Mapped: 5844 kB Slab: 155032 kB SReclaimable: 145804 kB SUnreclaim: 9228 kB PageTables: 1592 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 8388124 kB Committed_AS: 51732 kB VmallocTotal: 34359738367 kB VmallocUsed: 282604 kB VmallocChunk: 34359453499 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 6784 kB DirectMap2M: 4182016 kB Here's slabinfo: $ cat /proc/slabinfo slabinfo - version: 2.1 # name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> : tunables <limit> <batchcount> <sharedfactor> : slabdata <active_slabs> <num_slabs> <sharedavail> ip6_dst_cache 50 50 320 25 2 : tunables 0 0 0 : slabdata 2 2 0 UDPLITEv6 0 0 960 17 4 : tunables 0 0 0 : slabdata 0 0 0 UDPv6 68 68 960 17 4 : tunables 0 0 0 : slabdata 4 4 0 tw_sock_TCPv6 0 0 320 25 2 : tunables 0 0 0 : slabdata 0 0 0 TCPv6 72 72 1792 18 8 : tunables 0 0 0 : slabdata 4 4 0 dm_raid1_read_record 0 0 1064 30 8 : tunables 0 0 0 : slabdata 0 0 0 kcopyd_job 0 0 368 22 2 : tunables 0 0 0 : slabdata 0 0 0 dm_uevent 0 0 2608 12 8 : tunables 0 0 0 : slabdata 0 0 0 dm_rq_target_io 0 0 376 21 2 : tunables 0 0 0 : slabdata 0 0 0 uhci_urb_priv 0 0 56 73 1 : tunables 0 0 0 : slabdata 0 0 0 cfq_queue 0 0 168 24 1 : tunables 0 0 0 : slabdata 0 0 0 mqueue_inode_cache 18 18 896 18 4 : tunables 0 0 0 : slabdata 1 1 0 fuse_request 0 0 632 25 4 : tunables 0 0 0 : slabdata 0 0 0 fuse_inode 0 0 768 21 4 : tunables 0 0 0 : slabdata 0 0 0 ecryptfs_inode_cache 0 0 1024 16 4 : tunables 0 0 0 : slabdata 0 0 0 hugetlbfs_inode_cache 26 26 608 26 4 : tunables 0 0 0 : slabdata 1 1 0 journal_handle 680 680 24 170 1 : tunables 0 0 0 : slabdata 4 4 0 journal_head 144 144 112 36 1 : tunables 0 0 0 : slabdata 4 4 0 revoke_table 256 256 16 256 1 : tunables 0 0 0 : slabdata 1 1 0 revoke_record 512 512 32 128 1 : tunables 0 0 0 : slabdata 4 4 0 ext4_inode_cache 53306 53424 888 18 4 : tunables 0 0 0 : slabdata 2968 2968 0 ext4_free_block_extents 292 292 56 73 1 : tunables 0 0 0 : slabdata 4 4 0 ext4_alloc_context 112 112 144 28 1 : tunables 0 0 0 : slabdata 4 4 0 ext4_prealloc_space 156 156 104 39 1 : tunables 0 0 0 : slabdata 4 4 0 ext4_system_zone 0 0 40 102 1 : tunables 0 0 0 : slabdata 0 0 0 ext2_inode_cache 0 0 776 21 4 : tunables 0 0 0 : slabdata 0 0 0 ext3_inode_cache 0 0 784 20 4 : tunables 0 0 0 : slabdata 0 0 0 ext3_xattr 0 0 88 46 1 : tunables 0 0 0 : slabdata 0 0 0 dquot 0 0 256 16 1 : tunables 0 0 0 : slabdata 0 0 0 shmem_inode_cache 606 620 800 20 4 : tunables 0 0 0 : slabdata 31 31 0 pid_namespace 0 0 2112 15 8 : tunables 0 0 0 : slabdata 0 0 0 UDP-Lite 0 0 832 19 4 : tunables 0 0 0 : slabdata 0 0 0 RAW 183 210 768 21 4 : tunables 0 0 0 : slabdata 10 10 0 UDP 76 76 832 19 4 : tunables 0 0 0 : slabdata 4 4 0 tw_sock_TCP 80 80 256 16 1 : tunables 0 0 0 : slabdata 5 5 0 TCP 81 114 1664 19 8 : tunables 0 0 0 : slabdata 6 6 0 blkdev_integrity 144 144 112 36 1 : tunables 0 0 0 : slabdata 4 4 0 blkdev_queue 64 64 2024 16 8 : tunables 0 0 0 : slabdata 4 4 0 blkdev_requests 120 120 336 24 2 : tunables 0 0 0 : slabdata 5 5 0 fsnotify_event 156 156 104 39 1 : tunables 0 0 0 : slabdata 4 4 0 bip-256 7 7 4224 7 8 : tunables 0 0 0 : slabdata 1 1 0 bip-128 0 0 2176 15 8 : tunables 0 0 0 : slabdata 0 0 0 bip-64 0 0 1152 28 8 : tunables 0 0 0 : slabdata 0 0 0 bip-16 84 84 384 21 2 : tunables 0 0 0 : slabdata 4 4 0 sock_inode_cache 224 276 704 23 4 : tunables 0 0 0 : slabdata 12 12 0 file_lock_cache 88 88 184 22 1 : tunables 0 0 0 : slabdata 4 4 0 net_namespace 0 0 1920 17 8 : tunables 0 0 0 : slabdata 0 0 0 Acpi-ParseExt 640 672 72 56 1 : tunables 0 0 0 : slabdata 12 12 0 taskstats 48 48 328 24 2 : tunables 0 0 0 : slabdata 2 2 0 proc_inode_cache 1613 1750 640 25 4 : tunables 0 0 0 : slabdata 70 70 0 sigqueue 100 100 160 25 1 : tunables 0 0 0 : slabdata 4 4 0 radix_tree_node 22443 22475 560 29 4 : tunables 0 0 0 : slabdata 775 775 0 bdev_cache 72 72 896 18 4 : tunables 0 0 0 : slabdata 4 4 0 sysfs_dir_cache 9866 9894 80 51 1 : tunables 0 0 0 : slabdata 194 194 0 inode_cache 2268 2268 592 27 4 : tunables 0 0 0 : slabdata 84 84 0 dentry 285907 286062 192 21 1 : tunables 0 0 0 : slabdata 13622 13622 0 buffer_head 256447 257472 112 36 1 : tunables 0 0 0 : slabdata 7152 7152 0 vm_area_struct 1469 1541 176 23 1 : tunables 0 0 0 : slabdata 67 67 0 mm_struct 82 95 832 19 4 : tunables 0 0 0 : slabdata 5 5 0 files_cache 104 161 704 23 4 : tunables 0 0 0 : slabdata 7 7 0 signal_cache 163 187 960 17 4 : tunables 0 0 0 : slabdata 11 11 0 sighand_cache 145 165 2112 15 8 : tunables 0 0 0 : slabdata 11 11 0 task_xstate 118 140 576 28 4 : tunables 0 0 0 : slabdata 5 5 0 task_struct 128 165 5808 5 8 : tunables 0 0 0 : slabdata 33 33 0 anon_vma 731 896 32 128 1 : tunables 0 0 0 : slabdata 7 7 0 shared_policy_node 85 85 48 85 1 : tunables 0 0 0 : slabdata 1 1 0 numa_policy 170 170 24 170 1 : tunables 0 0 0 : slabdata 1 1 0 idr_layer_cache 240 240 544 30 4 : tunables 0 0 0 : slabdata 8 8 0 kmalloc-8192 27 32 8192 4 8 : tunables 0 0 0 : slabdata 8 8 0 kmalloc-4096 291 344 4096 8 8 : tunables 0 0 0 : slabdata 43 43 0 kmalloc-2048 225 240 2048 16 8 : tunables 0 0 0 : slabdata 15 15 0 kmalloc-1024 366 432 1024 16 4 : tunables 0 0 0 : slabdata 27 27 0 kmalloc-512 536 544 512 16 2 : tunables 0 0 0 : slabdata 34 34 0 kmalloc-256 406 528 256 16 1 : tunables 0 0 0 : slabdata 33 33 0 kmalloc-128 503 576 128 32 1 : tunables 0 0 0 : slabdata 18 18 0 kmalloc-64 3467 3712 64 64 1 : tunables 0 0 0 : slabdata 58 58 0 kmalloc-32 1520 1920 32 128 1 : tunables 0 0 0 : slabdata 15 15 0 kmalloc-16 3547 3840 16 256 1 : tunables 0 0 0 : slabdata 15 15 0 kmalloc-8 4607 4608 8 512 1 : tunables 0 0 0 : slabdata 9 9 0 kmalloc-192 4620 5313 192 21 1 : tunables 0 0 0 : slabdata 253 253 0 kmalloc-96 1780 1848 96 42 1 : tunables 0 0 0 : slabdata 44 44 0 kmem_cache_node 0 0 64 64 1 : tunables 0 0 0 : slabdata 0 0 0

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• How to disable or tune filesystem cache sharing for OpenVZ?

  - by gertvdijk

  For OpenVZ, an example of container-based virtualization, it seems that host and all guests are sharing the filesystem cache. This sounds paradoxical when talking about virtualization, but this is actually a feature of OpenVZ. It makes sense too. Because only one kernel is running, it's possible to benefit from sharing the same pages of filesystem cache in memory. And while it sounds beneficial, I think a set up here actually suffers in performance from it. Here's why I think why: my machines aren't actually sharing any files on disk so I can't benefit from this feature in OpenVZ. Several OpenVZ machines are running MySQL with MyISAM tables. MyISAM relies on the system's filesystem cache for caching of data files, unlike InnoDB's buffer pool. Also some virtual machines are known to do heavy and large I/O operations on the same filesystem in the host. For example, when running cat *.MYD > /dev/null on some large database in one machine, I saw the filesystem cache lowering in another, monitored by htop. This essentially flushes all the useful filesystem cache in guests (FIFO) and so it flushes the MySQL caches in the guests. Now users are complaining that MySQL is very slow. And it is. Some simple SELECT queries take several seconds on times disk I/O is heavily used by other machines. So, simply put: Is there a way to avoid filesystem cache being wiped out by other virtual machines in container-based virtualization? Some thoughts: Choosing algorithm for flushing filesystem cache in the kernel. (possible? how?) Reserving a certain amount of pages for a single VM. (seems no option for filesystem cache type of pages that reading man vzctl) Will running MySQL on another filesystem get me anywhere? If not, I think my alternatives are: Use KVM for MySQL-MyISAM running VMs. KVM actually assigns memory to the VM and does not allow swapping out caches unless using a balloon driver. Move to InnoDB and tune the buffer pools, dirty pages, etc. This is now considered to be 'nice to have' on the long-term as not everyone responsible for administration of the system understands InnoDB. more suggestions welcome. System software: Proxmox (now 1.9, could be upgraded to 2.x). One big LV assigned for the VMs.

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• FairScheduling Conventions in Hadoop

  - by dan.mcclary

  While scheduling and resource allocation control has been present in Hadoop since 0.20, a lot of people haven't discovered or utilized it in their initial investigations of the Hadoop ecosystem. We could chalk this up to many things: Organizations are still determining what their dataflow and analysis workloads will comprise Small deployments under tests aren't likely to show the signs of strains that would send someone looking for resource allocation options The default scheduling options -- the FairScheduler and the CapacityScheduler -- are not placed in the most prominent position within the Hadoop documentation. However, for production deployments, it's wise to start with at least the foundations of scheduling in place so that you can tune the cluster as workloads emerge. To do that, we have to ask ourselves something about what the off-the-rack scheduling options are. We have some choices: The FairScheduler, which will work to ensure resource allocations are enforced on a per-job basis. The CapacityScheduler, which will ensure resource allocations are enforced on a per-queue basis. Writing your own implementation of the abstract class org.apache.hadoop.mapred.job.TaskScheduler is an option, but usually overkill. If you're going to have several concurrent users and leverage the more interactive aspects of the Hadoop environment (e.g. Pig and Hive scripting), the FairScheduler is definitely the way to go. In particular, we can do user-specific pools so that default users get their fair share, and specific users are given the resources their workloads require. To enable fair scheduling, we're going to need to do a couple of things. First, we need to tell the JobTracker that we want to use scheduling and where we're going to be defining our allocations. We do this by adding the following to the mapred-site.xml file in HADOOP_HOME/conf: <property> <name>mapred.jobtracker.taskScheduler</name> <value>org.apache.hadoop.mapred.FairScheduler</value> </property> <property> <name>mapred.fairscheduler.allocation.file</name> <value>/path/to/allocations.xml</value> </property> <property> <name>mapred.fairscheduler.poolnameproperty</name> <value>pool.name</value> </property> <property> <name>pool.name</name> <value>${user.name}</name> </property> What we've done here is simply tell the JobTracker that we'd like to task scheduling to use the FairScheduler class rather than a single FIFO queue. Moreover, we're going to be defining our resource pools and allocations in a file called allocations.xml For reference, the allocation file is read every 15s or so, which allows for tuning allocations without having to take down the JobTracker. Our allocation file is now going to look a little like this <?xml version="1.0"?> <allocations> <pool name="dan"> <minMaps>5</minMaps> <minReduces>5</minReduces> <maxMaps>25</maxMaps> <maxReduces>25</maxReduces> <minSharePreemptionTimeout>300</minSharePreemptionTimeout> </pool> <mapreduce.job.user.name="dan"> <maxRunningJobs>6</maxRunningJobs> </user> <userMaxJobsDefault>3</userMaxJobsDefault> <fairSharePreemptionTimeout>600</fairSharePreemptionTimeout> </allocations> In this case, I've explicitly set my username to have upper and lower bounds on the maps and reduces, and allotted myself double the number of running jobs. Now, if I run hive or pig jobs from either the console or via the Hue web interface, I'll be treated "fairly" by the JobTracker. There's a lot more tweaking that can be done to the allocations file, so it's best to dig down into the description and start trying out allocations that might fit your workload.

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• SQL SERVER – Number-Crunching with SQL Server – Exceed the Functionality of Excel

  - by Pinal Dave

  Imagine this. Your users have developed an Excel spreadsheet that extracts data from your SQL Server database, manipulates that data through the use of Excel formulas and, possibly, some VBA code which is then used to calculate P&L, hedging requirements or even risk numbers. Management comes to you and tells you that they need to get rid of the spreadsheet and that the results of the spreadsheet calculations need to be persisted on the database. SQL Server has a very small set of functions for analyzing data. Excel has hundreds of functions for analyzing data, with many of them focused on specific financial and statistical calculations. Is it even remotely possible that you can use SQL Server to replace the complex calculations being done in a spreadsheet? Westclintech has developed a library of functions that match or exceed the functionality of Excel’s functions and contains many functions that are not available in EXCEL. Their XLeratorDB library of functions contains over 700 functions that can be incorporated into T-SQL statements. XLeratorDB takes advantage of the SQL CLR architecture introduced in SQL Server 2005. SQL CLR permits managed code to be compiled into the database and run alongside built-in SQL Server functions like COUNT or SUM. The Westclintech developers have taken advantage of this architecture to bring robust analytical functions to the database. In our hypothetical spreadsheet, let’s assume that our users are using the YIELD function and that the data are extracted from a table in our database called BONDS. Here’s what the spreadsheet might look like. We go to column G and see that it contains the following formula. Obviously, SQL Server does not offer a native YIELD function. However, with XLeratorDB we can replicate this calculation in SQL Server with the following statement: SELECT *, wct.YIELD(CAST(GETDATE() AS date),Maturity,Rate,Price,100,Frequency,Basis) AS YIELD FROM BONDS This produces the following result. This illustrates one of the best features about XLeratorDB; it is so easy to use. Since I knew that the spreadsheet was using the YIELD function I could use the same function with the same calling structure to do the calculation in SQL Server. I didn’t need to know anything at all about the mechanics of calculating the yield on a bond. It was pretty close to cut and paste. In fact, that’s one way to construct the SQL. Just copy the function call from the cell in the spreadsheet and paste it into SMS and change the cell references to column names. I built the SQL for this query by starting with this. SELECT * ,YIELD(TODAY(),B2,C2,D2,100,E2,F2) FROM BONDS I then changed the cell references to column names. SELECT * --,YIELD(TODAY(),B2,C2,D2,100,E2,F2) ,YIELD(TODAY(),Maturity,Rate,Price,100,Frequency,Basis) FROM BONDS Finally, I replicated the TODAY() function using GETDATE() and added the schema name to the function name. SELECT * --,YIELD(TODAY(),B2,C2,D2,100,E2,F2) --,YIELD(TODAY(),Maturity,Rate,Price,100,Frequency,Basis) ,wct.YIELD(GETDATE(),Maturity,Rate,Price,100,Frequency,Basis) FROM BONDS Then I am able to execute the statement returning the results seen above. The XLeratorDB libraries are heavy on financial, statistical, and mathematical functions. Where there is an analog to an Excel function, the XLeratorDB function uses the same naming conventions and calling structure as the Excel function, but there are also hundreds of additional functions for SQL Server that are not found in Excel. You can find the functions by opening Object Explorer in SQL Server Management Studio (SSMS) and expanding the Programmability folder under the database where the functions have been installed. The  Functions folder expands to show 3 sub-folders: Table-valued Functions; Scalar-valued functions, Aggregate Functions, and System Functions. You can expand any of the first three folders to see the XLeratorDB functions. Since the wct.YIELD function is a scalar function, we will open the Scalar-valued Functions folder, scroll down to the wct.YIELD function and and click the plus sign (+) to display the input parameters. The functions are also Intellisense-enabled, with the input parameters displayed directly in the query tab. The Westclintech website contains documentation for all the functions including examples that can be copied directly into a query window and executed. There are also more one hundred articles on the site which go into more detail about how some of the functions work and demonstrate some of the extensive business processes that can be done in SQL Server using XLeratorDB functions and some T-SQL. XLeratorDB is organized into libraries: finance, statistics; math; strings; engineering; and financial options. There is also a windowing library for SQL Server 2005, 2008, and 2012 which provides functions for calculating things like running and moving averages (which were introduced in SQL Server 2012), FIFO inventory calculations, financial ratios and more, without having to use triangular joins. To get started you can download the XLeratorDB 15-day free trial from the Westclintech web site. It is a fully-functioning, unrestricted version of the software. If you need more than 15 days to evaluate the software, you can simply download another 15-day free trial. XLeratorDB is an easy and cost-effective way to start adding sophisticated data analysis to your SQL Server database without having to know anything more than T-SQL. Get XLeratorDB Today and Now! Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Excel

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• SSAS Maestro Training in July 2012 #ssasmaestro #ssas

  - by Marco Russo (SQLBI)

  A few hours ago Chris Webb blogged about SSAS Maestro and I’d like to propagate the news, adding also some background info. SSAS Maestro is the premier certification on Analysis Services that selects the best experts in Analysis Services around the world. In 2011 Microsoft organized two rounds of training/exams for SSAS Maestros and up to now only 11 people from the first wave have been announced – around 10% of attendees of the course! In the next few days the new Maestros from the second round should be announced and this long process is caused by many factors that I’m going to explain. First, the course is just a step in the process. Before the course you receive a list of topics to study, including the slides of the course. During the course, students receive a lot of information that might not have been included in the slides and the best part of the course is class interaction. Students are expected to bring their experience to the table and comparing case studies, experiences and having long debates is an important part of the learning process. And it is also a part of the evaluation: good questions might be also more important than good answers! Finally, after the course, students have their homework and this may require one or two months to be completed. After that, a long (very long) evaluation process begins, taking into account homework, labs, participation… And for this reason the final evaluation may arrive months later after the course. We are going to improve and shorten this process with the next courses. The first wave of SSAS Maestro had been made by invitation only and now the program is opening, requiring a fee to participate in order to cover the cost of preparation, training and exam. The number of attendees will be limited and candidates will have to send their CV in order to be admitted to the course. Only experienced Analysis Services developers will be able to participate to this challenging program. So why you should do that? Well, only 10% of students passed the exam until now. So if you need 100% guarantee to pass the exam, you need to study a lot, before, during and after the course. But the course by itself is a precious opportunity to share experience, create networking and learn mission-critical enterprise-level best practices that it’s hard to find written on books. Oh, well, many existing white papers are a required reading *before* the course! The course is now 5 days long, and every day can be *very* long. We’ll have lectures and discussions in the morning and labs in the afternoon/evening. Plus some more lectures in one or two afternoons. A heavy part of the course is about performance optimization, capacity planning, monitoring. This edition will introduce also Tabular models, and don’t expect something you might find in the SSAS Tabular Workshop – only performance, scalability monitoring and optimization will be covered, knowing Analysis Services is a requirement just to be accepted! I and Chris Webb will be the teachers for this edition. The course is expensive. Applying for SSAS Maestro will cost around 7000€ plus taxes (reduced to 5000€ for students of a previous SSAS Maestro edition). And you will be locked in a training room for the large part of the week. So why you should do that? Well, as I said, this is a challenging course. You will not find the time to check your email – the content is just too much interesting to think you can be distracted by something else. Another good reason is that this course will take place in Italy. Well, the course will take place in the brand new Microsoft Innovation Campus, but in general we’ll be able to provide you hints to get great food and, if you are willing to attach one week-end to your trip, there are plenty of places to visit (and I’m not talking about the classic Rome-Florence-Venice) – you might really need to relax after such a week! Finally, the marking process after the course will be faster – we’d like to complete the evaluation within three months after the course, considering that 1-2 months might be required to complete the homework. If at this point you are not scared: registration will open in mid-April, but you can already write to [email protected] sending your CV/resume and a short description of your level of SSAS knowledge and experience. The selection process will start early and you may want to put your admission form on top of the FIFO queue!

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• High Linux loads on low CPU/memory usage

  - by user13323

  Hi. I have quite strange situation, where my CentOS 5.5 box loads are high, but the CPU and memory used are pretty low: top - 20:41:38 up 42 days, 6:14, 2 users, load average: 19.79, 21.25, 18.87 Tasks: 254 total, 1 running, 253 sleeping, 0 stopped, 0 zombie Cpu(s): 3.8%us, 0.3%sy, 0.1%ni, 95.0%id, 0.6%wa, 0.0%hi, 0.1%si, 0.0%st Mem: 4035284k total, 4008084k used, 27200k free, 38748k buffers Swap: 4208928k total, 242576k used, 3966352k free, 1465008k cached free -mt total used free shared buffers cached Mem: 3940 3910 29 0 37 1427 -/+ buffers/cache: 2445 1495 Swap: 4110 236 3873 Total: 8050 4147 3903 Iostat also shows good results: avg-cpu: %user %nice %system %iowait %steal %idle 3.83 0.13 0.41 0.58 0.00 95.05 Here is the ps aux output: USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0.0 0.0 10348 80 ? Ss 2010 2:11 init [3] root 2 0.0 0.0 0 0 ? S< 2010 0:00 [migration/0] root 3 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/0] root 4 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/0] root 5 0.0 0.0 0 0 ? S< 2010 0:02 [migration/1] root 6 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/1] root 7 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/1] root 8 0.0 0.0 0 0 ? S< 2010 0:02 [migration/2] root 9 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/2] root 10 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/2] root 11 0.0 0.0 0 0 ? S< 2010 0:02 [migration/3] root 12 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/3] root 13 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/3] root 14 0.0 0.0 0 0 ? S< 2010 0:03 [migration/4] root 15 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/4] root 16 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/4] root 17 0.0 0.0 0 0 ? S< 2010 0:01 [migration/5] root 18 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/5] root 19 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/5] root 20 0.0 0.0 0 0 ? S< 2010 0:11 [migration/6] root 21 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/6] root 22 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/6] root 23 0.0 0.0 0 0 ? S< 2010 0:01 [migration/7] root 24 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/7] root 25 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/7] root 26 0.0 0.0 0 0 ? S< 2010 0:00 [migration/8] root 27 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/8] root 28 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/8] root 29 0.0 0.0 0 0 ? S< 2010 0:00 [migration/9] root 30 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/9] root 31 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/9] root 32 0.0 0.0 0 0 ? S< 2010 0:08 [migration/10] root 33 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/10] root 34 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/10] root 35 0.0 0.0 0 0 ? S< 2010 0:05 [migration/11] root 36 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/11] root 37 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/11] root 38 0.0 0.0 0 0 ? S< 2010 0:02 [migration/12] root 39 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/12] root 40 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/12] root 41 0.0 0.0 0 0 ? S< 2010 0:14 [migration/13] root 42 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/13] root 43 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/13] root 44 0.0 0.0 0 0 ? S< 2010 0:04 [migration/14] root 45 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/14] root 46 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/14] root 47 0.0 0.0 0 0 ? S< 2010 0:01 [migration/15] root 48 0.0 0.0 0 0 ? SN 2010 0:00 [ksoftirqd/15] root 49 0.0 0.0 0 0 ? S< 2010 0:00 [watchdog/15] root 50 0.0 0.0 0 0 ? S< 2010 0:00 [events/0] root 51 0.0 0.0 0 0 ? S< 2010 0:00 [events/1] root 52 0.0 0.0 0 0 ? S< 2010 0:00 [events/2] root 53 0.0 0.0 0 0 ? S< 2010 0:00 [events/3] root 54 0.0 0.0 0 0 ? S< 2010 0:00 [events/4] root 55 0.0 0.0 0 0 ? S< 2010 0:00 [events/5] root 56 0.0 0.0 0 0 ? S< 2010 0:00 [events/6] root 57 0.0 0.0 0 0 ? S< 2010 0:00 [events/7] root 58 0.0 0.0 0 0 ? S< 2010 0:00 [events/8] root 59 0.0 0.0 0 0 ? S< 2010 0:00 [events/9] root 60 0.0 0.0 0 0 ? S< 2010 0:00 [events/10] root 61 0.0 0.0 0 0 ? S< 2010 0:00 [events/11] root 62 0.0 0.0 0 0 ? S< 2010 0:00 [events/12] root 63 0.0 0.0 0 0 ? S< 2010 0:00 [events/13] root 64 0.0 0.0 0 0 ? S< 2010 0:00 [events/14] root 65 0.0 0.0 0 0 ? S< 2010 0:00 [events/15] root 66 0.0 0.0 0 0 ? S< 2010 0:00 [khelper] root 107 0.0 0.0 0 0 ? S< 2010 0:00 [kthread] root 126 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/0] root 127 0.0 0.0 0 0 ? S< 2010 0:03 [kblockd/1] root 128 0.0 0.0 0 0 ? S< 2010 0:01 [kblockd/2] root 129 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/3] root 130 0.0 0.0 0 0 ? S< 2010 0:05 [kblockd/4] root 131 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/5] root 132 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/6] root 133 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/7] root 134 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/8] root 135 0.0 0.0 0 0 ? S< 2010 0:02 [kblockd/9] root 136 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/10] root 137 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/11] root 138 0.0 0.0 0 0 ? S< 2010 0:04 [kblockd/12] root 139 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/13] root 140 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/14] root 141 0.0 0.0 0 0 ? S< 2010 0:00 [kblockd/15] root 142 0.0 0.0 0 0 ? S< 2010 0:00 [kacpid] root 281 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/0] root 282 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/1] root 283 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/2] root 284 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/3] root 285 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/4] root 286 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/5] root 287 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/6] root 288 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/7] root 289 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/8] root 290 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/9] root 291 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/10] root 292 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/11] root 293 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/12] root 294 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/13] root 295 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/14] root 296 0.0 0.0 0 0 ? S< 2010 0:00 [cqueue/15] root 299 0.0 0.0 0 0 ? S< 2010 0:00 [khubd] root 301 0.0 0.0 0 0 ? S< 2010 0:00 [kseriod] root 490 0.0 0.0 0 0 ? S 2010 0:00 [khungtaskd] root 493 0.1 0.0 0 0 ? S< 2010 94:48 [kswapd1] root 494 0.0 0.0 0 0 ? S< 2010 0:00 [aio/0] root 495 0.0 0.0 0 0 ? S< 2010 0:00 [aio/1] root 496 0.0 0.0 0 0 ? S< 2010 0:00 [aio/2] root 497 0.0 0.0 0 0 ? S< 2010 0:00 [aio/3] root 498 0.0 0.0 0 0 ? S< 2010 0:00 [aio/4] root 499 0.0 0.0 0 0 ? S< 2010 0:00 [aio/5] root 500 0.0 0.0 0 0 ? S< 2010 0:00 [aio/6] root 501 0.0 0.0 0 0 ? S< 2010 0:00 [aio/7] root 502 0.0 0.0 0 0 ? S< 2010 0:00 [aio/8] root 503 0.0 0.0 0 0 ? S< 2010 0:00 [aio/9] root 504 0.0 0.0 0 0 ? S< 2010 0:00 [aio/10] root 505 0.0 0.0 0 0 ? S< 2010 0:00 [aio/11] root 506 0.0 0.0 0 0 ? S< 2010 0:00 [aio/12] root 507 0.0 0.0 0 0 ? S< 2010 0:00 [aio/13] root 508 0.0 0.0 0 0 ? S< 2010 0:00 [aio/14] root 509 0.0 0.0 0 0 ? S< 2010 0:00 [aio/15] root 665 0.0 0.0 0 0 ? S< 2010 0:00 [kpsmoused] root 808 0.0 0.0 0 0 ? S< 2010 0:00 [ata/0] root 809 0.0 0.0 0 0 ? S< 2010 0:00 [ata/1] root 810 0.0 0.0 0 0 ? S< 2010 0:00 [ata/2] root 811 0.0 0.0 0 0 ? S< 2010 0:00 [ata/3] root 812 0.0 0.0 0 0 ? S< 2010 0:00 [ata/4] root 813 0.0 0.0 0 0 ? S< 2010 0:00 [ata/5] root 814 0.0 0.0 0 0 ? S< 2010 0:00 [ata/6] root 815 0.0 0.0 0 0 ? S< 2010 0:00 [ata/7] root 816 0.0 0.0 0 0 ? S< 2010 0:00 [ata/8] root 817 0.0 0.0 0 0 ? S< 2010 0:00 [ata/9] root 818 0.0 0.0 0 0 ? S< 2010 0:00 [ata/10] root 819 0.0 0.0 0 0 ? S< 2010 0:00 [ata/11] root 820 0.0 0.0 0 0 ? S< 2010 0:00 [ata/12] root 821 0.0 0.0 0 0 ? S< 2010 0:00 [ata/13] root 822 0.0 0.0 0 0 ? S< 2010 0:00 [ata/14] root 823 0.0 0.0 0 0 ? S< 2010 0:00 [ata/15] root 824 0.0 0.0 0 0 ? S< 2010 0:00 [ata_aux] root 842 0.0 0.0 0 0 ? S< 2010 0:00 [scsi_eh_0] root 843 0.0 0.0 0 0 ? S< 2010 0:00 [scsi_eh_1] root 844 0.0 0.0 0 0 ? S< 2010 0:00 [scsi_eh_2] root 845 0.0 0.0 0 0 ? S< 2010 0:00 [scsi_eh_3] root 846 0.0 0.0 0 0 ? S< 2010 0:00 [scsi_eh_4] root 847 0.0 0.0 0 0 ? S< 2010 0:00 [scsi_eh_5] root 882 0.0 0.0 0 0 ? S< 2010 0:00 [kstriped] root 951 0.0 0.0 0 0 ? S< 2010 4:24 [kjournald] root 976 0.0 0.0 0 0 ? S< 2010 0:00 [kauditd] postfix 990 0.0 0.0 54208 2284 ? S 21:19 0:00 pickup -l -t fifo -u root 1013 0.0 0.0 12676 8 ? S<s 2010 0:00 /sbin/udevd -d root 1326 0.0 0.0 90900 3400 ? Ss 14:53 0:00 sshd: root@notty root 1410 0.0 0.0 53972 2108 ? Ss 14:53 0:00 /usr/libexec/openssh/sftp-server root 2690 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/0] root 2691 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/1] root 2692 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/2] root 2693 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/3] root 2694 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/4] root 2695 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/5] root 2696 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/6] root 2697 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/7] root 2698 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/8] root 2699 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/9] root 2700 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/10] root 2701 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/11] root 2702 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/12] root 2703 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/13] root 2704 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/14] root 2705 0.0 0.0 0 0 ? S< 2010 0:00 [kmpathd/15] root 2706 0.0 0.0 0 0 ? S< 2010 0:00 [kmpath_handlerd] root 2755 0.0 0.0 0 0 ? S< 2010 4:35 [kjournald] root 2757 0.0 0.0 0 0 ? S< 2010 3:38 [kjournald] root 2759 0.0 0.0 0 0 ? S< 2010 4:10 [kjournald] root 2761 0.0 0.0 0 0 ? S< 2010 4:26 [kjournald] root 2763 0.0 0.0 0 0 ? S< 2010 3:15 [kjournald] root 2765 0.0 0.0 0 0 ? S< 2010 3:04 [kjournald] root 2767 0.0 0.0 0 0 ? S< 2010 3:02 [kjournald] root 2769 0.0 0.0 0 0 ? S< 2010 2:58 [kjournald] root 2771 0.0 0.0 0 0 ? S< 2010 0:00 [kjournald] root 3340 0.0 0.0 5908 356 ? Ss 2010 2:48 syslogd -m 0 root 3343 0.0 0.0 3804 212 ? Ss 2010 0:03 klogd -x root 3430 0.0 0.0 0 0 ? S< 2010 0:50 [kondemand/0] root 3431 0.0 0.0 0 0 ? S< 2010 0:54 [kondemand/1] root 3432 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/2] root 3433 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/3] root 3434 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/4] root 3435 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/5] root 3436 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/6] root 3437 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/7] root 3438 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/8] root 3439 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/9] root 3440 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/10] root 3441 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/11] root 3442 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/12] root 3443 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/13] root 3444 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/14] root 3445 0.0 0.0 0 0 ? S< 2010 0:00 [kondemand/15] root 3461 0.0 0.0 10760 284 ? Ss 2010 3:44 irqbalance rpc 3481 0.0 0.0 8052 4 ? Ss 2010 0:00 portmap root 3526 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/0] root 3527 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/1] root 3528 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/2] root 3529 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/3] root 3530 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/4] root 3531 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/5] root 3532 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/6] root 3533 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/7] root 3534 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/8] root 3535 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/9] root 3536 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/10] root 3537 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/11] root 3538 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/12] root 3539 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/13] root 3540 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/14] root 3541 0.0 0.0 0 0 ? S< 2010 0:00 [rpciod/15] root 3563 0.0 0.0 10160 8 ? Ss 2010 0:00 rpc.statd root 3595 0.0 0.0 55180 4 ? Ss 2010 0:00 rpc.idmapd dbus 3618 0.0 0.0 21256 28 ? Ss 2010 0:00 dbus-daemon --system root 3649 0.2 0.4 563084 18796 ? S<sl 2010 179:03 mfsmount /mnt/mfs -o rw,mfsmaster=web1.ovs.local root 3702 0.0 0.0 3800 8 ? Ss 2010 0:00 /usr/sbin/acpid 68 3715 0.0 0.0 31312 816 ? Ss 2010 3:14 hald root 3716 0.0 0.0 21692 28 ? S 2010 0:00 hald-runner 68 3726 0.0 0.0 12324 8 ? S 2010 0:00 hald-addon-acpi: listening on acpid socket /var/run/acpid.socket 68 3730 0.0 0.0 12324 8 ? S 2010 0:00 hald-addon-keyboard: listening on /dev/input/event0 root 3773 0.0 0.0 62608 332 ? Ss 2010 0:00 /usr/sbin/sshd ganglia 3786 0.0 0.0 24704 988 ? Ss 2010 14:26 /usr/sbin/gmond root 3843 0.0 0.0 54144 300 ? Ss 2010 1:49 /usr/libexec/postfix/master postfix 3855 0.0 0.0 54860 1060 ? S 2010 0:22 qmgr -l -t fifo -u root 3877 0.0 0.0 74828 708 ? Ss 2010 1:15 crond root 3891 1.4 1.9 326960 77704 ? S<l 2010 896:59 mfschunkserver root 4122 0.0 0.0 18732 176 ? Ss 2010 0:10 /usr/sbin/atd root 4193 0.0 0.8 129180 35984 ? Ssl 2010 11:04 /usr/bin/ruby /usr/sbin/puppetd root 4223 0.0 0.0 18416 172 ? S 2010 0:10 /usr/sbin/smartd -q never root 4227 0.0 0.0 3792 8 tty1 Ss+ 2010 0:00 /sbin/mingetty tty1 root 4230 0.0 0.0 3792 8 tty2 Ss+ 2010 0:00 /sbin/mingetty tty2 root 4231 0.0 0.0 3792 8 tty3 Ss+ 2010 0:00 /sbin/mingetty tty3 root 4233 0.0 0.0 3792 8 tty4 Ss+ 2010 0:00 /sbin/mingetty tty4 root 4234 0.0 0.0 3792 8 tty5 Ss+ 2010 0:00 /sbin/mingetty tty5 root 4236 0.0 0.0 3792 8 tty6 Ss+ 2010 0:00 /sbin/mingetty tty6 root 5596 0.0 0.0 19368 20 ? Ss 2010 0:00 DarwinStreamingServer qtss 5597 0.8 0.9 166572 37408 ? Sl 2010 523:02 DarwinStreamingServer root 8714 0.0 0.0 0 0 ? S Jan31 0:33 [pdflush] root 9914 0.0 0.0 65612 968 pts/1 R+ 21:49 0:00 ps aux root 10765 0.0 0.0 76792 1080 ? Ss Jan24 0:58 SCREEN root 10766 0.0 0.0 66212 872 pts/3 Ss Jan24 0:00 /bin/bash root 11833 0.0 0.0 63852 1060 pts/3 S+ 17:17 0:00 /bin/sh ./launch.sh root 11834 437 42.9 4126884 1733348 pts/3 Sl+ 17:17 1190:50 /usr/bin/java -Xms128m -Xmx512m -XX:+UseConcMarkSweepGC -jar /JavaCore/JavaCore.jar root 13127 4.7 1.1 110564 46876 ? Ssl 17:18 12:55 /JavaCore/fetcher.bin root 19392 0.0 0.0 90108 3336 ? Rs 20:35 0:00 sshd: root@pts/1 root 19401 0.0 0.0 66216 1640 pts/1 Ss 20:35 0:00 -bash root 20567 0.0 0.0 90108 412 ? Ss Jan16 1:58 sshd: root@pts/0 root 20569 0.0 0.0 66084 912 pts/0 Ss Jan16 0:00 -bash root 21053 0.0 0.0 63856 28 ? S Jan30 0:00 /bin/sh /usr/bin/WowzaMediaServerd /usr/local/WowzaMediaServer/bin/setenv.sh /var/run/WowzaM root 21054 2.9 10.3 2252652 418468 ? Sl Jan30 314:25 java -Xmx1200M -server -Djava.net.preferIPv4Stack=true -Dcom.sun.management.jmxremote=true - root 21915 0.0 0.0 0 0 ? S Feb01 0:00 [pdflush] root 29996 0.0 0.0 76524 1004 pts/0 S+ 14:41 0:00 screen -x Any idea what could this be, or where I should look for more diagnostic information? Thanks.

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• Speed Problem with Wireless Connectivity on Cisco 877w

  - by Carl Crawley

  Having a bit of a weird one with my local LAN setup. I recently installed a Cisco 877W router on my DSL2+ connection and all is working really well.. Upgraded the IOS to 12.4 and my wired clients are streaming connectivity superfast at 1.3mb/s. However, there seems to be an issue with my wireless clients - I can't seem to stream any data across the local wireless connection (LAN) and using the Internet, whilst responsive enough isn't really comparable with the wired connection speed. For example, all devices are connected to an 8 Port Gb switch on FE0 from the Router with a NAS disk and on my wired clients, I can transfer/stream etc absolutely fine - however, transferring a local 700Mb file on my local LAN estimates 7-8 hours to transfer :( The Wireless config is as follows : interface Dot11Radio0 description WIRELESS INTERFACE no ip address ! encryption mode ciphers tkip ! ssid [MySSID] ! speed basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 channel 2462 station-role root rts threshold 2312 world-mode dot11d country GB indoor bridge-group 1 bridge-group 1 subscriber-loop-control bridge-group 1 spanning-disabled bridge-group 1 block-unknown-source no bridge-group 1 source-learning no bridge-group 1 unicast-flooding All devices are connected to the Gb Switch which is connected to FE0 with the following: Hardware is Fast Ethernet, address is 0021.a03e.6519 (bia 0021.a03e.6519) Description: Uplink to Switch MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Full-duplex, 100Mb/s ARP type: ARPA, ARP Timeout 04:00:00 Last input never, output never, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/40 (size/max) 5 minute input rate 14000 bits/sec, 19 packets/sec 5 minute output rate 167000 bits/sec, 23 packets/sec 177365 packets input, 52089562 bytes, 0 no buffer Received 919 broadcasts, 0 runts, 0 giants, 0 throttles 260 input errors, 260 CRC, 0 frame, 0 overrun, 0 ignored 0 input packets with dribble condition detected 156673 packets output, 106218222 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier 0 output buffer failures, 0 output buffers swapped out Not sure why I'm having problems on the wireless and I've reached the end of my Cisco knowledge... Thanks for any pointers! Carl

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• Unlocking a mutex from a different thread (C++)

  - by dan

  I'm using the C++ boost::thread library, which in my case means I'm using pthreads. Officially, a mutex must be unlocked from the same thread which locks it, and I want the effect of being able to lock in one thread and then unlock in another. There are many ways to accomplish this. One possibility would be to write a new mutex class which allows this behavior. For example: class inter_thread_mutex{ bool locked; boost::mutex mx; boost::condition_variable cv; public: void lock(){ boost::unique_lock<boost::mutex> lck(mx); while(locked) cv.wait(lck); locked=true; } void unlock(){ { boost::lock_guard<boost::mutex> lck(mx); if(!locked) error(); locked=false; } cv.notify_one(); } // bool try_lock(); void error(); etc. } I should point out that the above code doesn't guarantee FIFO access, since if one thread calls lock() while another calls unlock(), this first thread may acquire the lock ahead of other threads which are waiting. (Come to think of it, the boost::thread documentation doesn't appear to make any explicit scheduling guarantees for either mutexes or condition variables). But let's just ignore that (and any other bugs) for now. My question is, if I decide to go this route, would I be able to use such a mutex as a model for the boost Lockable concept. For example, would anything go wrong if I use a boost::unique_lock< inter_thread_mutex for RAII-style access, and then pass this lock to boost::condition_variable_any.wait(), etc. On one hand I don't see why not. On the other hand, "I don't see why not" is usually a very bad way of determining whether something will work. The reason I ask is that if it turns out that I have to write wrapper classes for RAII locks and condition variables and whatever else, then I'd rather just find some other way to achieve the same effect.

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• Abnormally disconnected TCP sockets and write timeout

  - by James

  Hello I will try to explain the problem in shortest possible words. I am using c++ builder 2010. I am using TIdTCPServer and sending voice packets to a list of connected clients. Everything works ok untill any client is disconnected abnormally, For example power failure etc. I can reproduce similar disconnect by cutting the ethernet connection of a connected client. So now we have a disconnected socket but as you know it is not yet detected at server side so server will continue to try to send data to that client too. But when server try to write data to that disconnected client ...... Write() or WriteLn() HANGS there in trying to write, It is like it is wating for somekind of Write timeout. This hangs the hole packet distribution process as a result creating a lag in data transmission to all other clients. After few seconds "Socket Connection Closed" Exception is raised and data flow continues. Here is the code try { EnterCriticalSection(&SlotListenersCriticalSection); for(int i=0;i<SlotListeners->Count;i++) { try { //Here the process will HANG for several seconds on a disconnected socket ((TIdContext*) SlotListeners->Objects[i])->Connection->IOHandler->WriteLn("Some DATA"); }catch(Exception &e) { SlotListeners->Delete(i); } } }__finally { LeaveCriticalSection(&SlotListenersCriticalSection); } Ok i already have a keep alive mechanism which disconnect the socket after n seconds of inactivity. But as you can imagine, still this mechnism cant sync exactly with this braodcasting loop because this braodcasting loop is running almost all the time. So is there any Write timeouts i can specify may be through iohandler or something ? I have seen many many threads about "Detecting disconnected tcp socket" but my problem is little different, i need to avoid that hangup for few seconds during the write attempt. So is there any solution ? Or should i consider using some different mechanism for such data broadcasting for example the broadcasting loop put the data packet in some kind of FIFO buffer and client threads continuously check for available data and pick and deliver it to themselves ? This way if one thread hangs it will not stop/delay the over all distribution thread. Any ideas please ? Thanks for your time and help. Regards Jams

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• how to deal with the position in a c# stream

  - by CapsicumDreams

  The (entire) documentation for the position property on a stream says: When overridden in a derived class, gets or sets the position within the current stream. The Position property does not keep track of the number of bytes from the stream that have been consumed, skipped, or both. That's it. OK, so we're fairly clear on what it doesn't tell us, but I'd really like to know what it in fact does stand for. What is 'the position' for? Why would we want to alter or read it? If we change it - what happens? In a pratical example, I have a a stream that periodically gets written to, and I have a thread that attempts to read from it (ideally ASAP). From reading many SO issues, I reset the position field to zero to start my reading. Once this is done: Does this affect where the writer to this stream is going to attempt to put the data? Do I need to keep track of the last write position myself? (ie if I set the position to zero to read, does the writer begin to overwrite everything from the first byte?) If so, do I need a semaphore/lock around this 'position' field (subclassing, perhaps?) due to my two threads accessing it? If I don't handle this property, does the writer just overflow the buffer? Perhaps I don't understand the Stream itself - I'm regarding it as a FIFO pipe: shove data in at one end, and suck it out at the other. If it's not like this, then do I have to keep copying the data past my last read (ie from position 0x84 on) back to the start of my buffer? I've seriously tried to research all of this for quite some time - but I'm new to .NET. Perhaps the Streams have a long, proud (undocumented) history that everyone else implicitly understands. But for a newcomer, it's like reading the manual to your car, and finding out: The accelerator pedal affects the volume of fuel and air sent to the fuel injectors. It does not affect the volume of the entertainment system, or the air pressure in any of the tires, if fitted. Technically true, but seriously, what we want to know is that if we mash it to the floor you go faster..

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• Rsyslog is not working properly, it does not log anything

  - by Victor Henriquez

  I'm running a Debian server and a couple of days ago my rsyslog started to behave very weird, the daemon is running but it doesn't seem to do anything. Many people use the system but I'm the only one with (legal) root access. I'm using the default rsyslogd configuration (if you think is relevant I'll attach it, but it's the one that comes with the package). After I rotated all the log files, they have remained empty: # ls -l /var/log/*.log -rw-r--r-- 1 root root 0 Jun 27 00:25 /var/log/alternatives.log -rw-r----- 1 root adm 0 Jun 26 13:03 /var/log/auth.log -rw-r----- 1 root adm 0 Jun 26 13:03 /var/log/daemon.log -rw-r--r-- 1 root root 0 Jun 27 00:25 /var/log/dpkg.log -rw-r----- 1 root adm 0 Jun 26 13:03 /var/log/kern.log -rw-r----- 1 root adm 0 Jun 26 13:03 /var/log/lpr.log -rw-r----- 1 root adm 0 Jun 26 13:03 /var/log/mail.log -rw-r----- 1 root adm 0 Jun 26 13:03 /var/log/user.log Any try to force a log writing does not have any effect: # logger hey # ls -l /var/log/messages -rw-r----- 1 root adm 0 Jun 26 13:03 /var/log/messages Lsof shows that rsyslogd does not have any log files opened: # lsof -p 1855 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME rsyslogd 1855 root cwd DIR 202,0 4096 2 / rsyslogd 1855 root rtd DIR 202,0 4096 2 / rsyslogd 1855 root txt REG 202,0 342076 21649 /usr/sbin/rsyslogd rsyslogd 1855 root mem REG 202,0 38556 32153 /lib/i386-linux-gnu/i686/cmov/libnss_nis-2.13.so rsyslogd 1855 root mem REG 202,0 79728 32165 /lib/i386-linux-gnu/i686/cmov/libnsl-2.13.so rsyslogd 1855 root mem REG 202,0 26456 32163 /lib/i386-linux-gnu/i686/cmov/libnss_compat-2.13.so rsyslogd 1855 root mem REG 202,0 297500 1061058 /usr/lib/rsyslog/imuxsock.so rsyslogd 1855 root mem REG 202,0 42628 32170 /lib/i386-linux-gnu/i686/cmov/libnss_files-2.13.so rsyslogd 1855 root mem REG 202,0 22784 1061106 /usr/lib/rsyslog/imklog.so rsyslogd 1855 root mem REG 202,0 1401000 32169 /lib/i386-linux-gnu/i686/cmov/libc-2.13.so rsyslogd 1855 root mem REG 202,0 30684 32175 /lib/i386-linux-gnu/i686/cmov/librt-2.13.so rsyslogd 1855 root mem REG 202,0 9844 32157 /lib/i386-linux-gnu/i686/cmov/libdl-2.13.so rsyslogd 1855 root mem REG 202,0 117009 32154 /lib/i386-linux-gnu/i686/cmov/libpthread-2.13.so rsyslogd 1855 root mem REG 202,0 79980 17746 /usr/lib/libz.so.1.2.3.4 rsyslogd 1855 root mem REG 202,0 18836 1061094 /usr/lib/rsyslog/lmnet.so rsyslogd 1855 root mem REG 202,0 117960 31845 /lib/i386-linux-gnu/ld-2.13.so rsyslogd 1855 root 0u unix 0xebe8e800 0t0 640 /dev/log rsyslogd 1855 root 3u FIFO 0,5 0t0 2474 /dev/xconsole rsyslogd 1855 root 4u unix 0xebe8e400 0t0 645 /var/spool/postfix/dev/log rsyslogd 1855 root 5r REG 0,3 0 4026532176 /proc/kmsg I was so frustrated that even reinstall the rsyslog package, but it still refuses to log anything: # apt-get remove --purge rsyslog # apt-get install rsyslog I thought someone had hacked the system, so run rkhunter, chkrootkit, unhide in an attempt to find hide processes / ports and nmap in a remote host to compare with the ports shown by netstat. And I know this doesn't mean anything, but all looks ok. The system also have an iptables firewall that is very restrictive with incoming / outgoing connections. This is driving me crazy, any idea what is going on here? [EDIT - disk space info] # df -h Filesystem Size Used Avail Use% Mounted on rootfs 24G 22G 629M 98% / /dev/root 24G 22G 629M 98% / devtmpfs 10M 112K 9.9M 2% /dev tmpfs 76M 48K 76M 1% /run tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs 151M 40K 151M 1% /tmp tmpfs 151M 0 151M 0% /run/shm

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• Log transport and aggregation at scale

  - by markdrayton

  How're you analysing log files from UNIX/Linux machines? We run several hundred servers which all generate their own log files, either directly or through syslog. I'm looking for a decent solution to aggregate these and pick out important events. This problem breaks down into 3 components: 1) Message transport The classic way is to use syslog to log messages to a remote host. This works fine for applications that log into syslog but less useful for apps that write to a local file. Solutions for this might include having the application log into a FIFO connected to a program to send the message using syslog, or by writing something that will grep the local files and send the output to the central syslog host. However, if we go to the trouble of writing tools to get messages into syslog would we be better replacing the whole lot with something like Facebook's Scribe which offers more flexibility and reliability than syslog? 2) Message aggregation Log entries seem to fall into one of two types: per-host and per-service. Per-host messages are those which occur on one machine; think disk failures or suspicious logins. Per-service messages occur on most or all of the hosts running a service. For instance, we want to know when Apache finds an SSI error but we don't want the same error from 100 machines. In all cases we only want to see one of each type of message: we don't want 10 messages saying the same disk has failed, and we don't want a message each time a broken SSI is hit. One approach to solving this is to aggregate multiple messages of the same type into one on each host, send the messages to a central server and then aggregate messages of the same kind into one overall event. SER can do this but it's awkward to use. Even after a couple of days of fiddling I had only rudimentary aggregations working and had to constantly look up the logic SER uses to correlate events. It's powerful but tricky stuff: I need something which my colleagues can pick up and use in the shortest possible time. SER rules don't meet that requirement. 3) Generating alerts How do we tell our admins when something interesting happens? Mail the group inbox? Inject into Nagios? So, how're you solving this problem? I don't expect an answer on a plate; I can work out the details myself but some high-level discussion on what is surely a common problem would be great. At the moment we're using a mishmash of cron jobs, syslog and who knows what else to find events. This isn't extensible, maintainable or flexible and as such we miss a lot of stuff we shouldn't. Updated: we're already using Nagios for monitoring which is great for detected down hosts/testing services/etc but less useful for scraping log files. I know there are log plugins for Nagios but I'm interested in something more scalable and hierarchical than per-host alerts.

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• Can't configure frame relay T1 on Cisco 1760

  - by sonar

  For the past few days I've been trying to configure a data T1 via a Frame Relay. Now I've been pretty unsuccessful at it, and it's been a while, since I've done this so please bare with me. The ISP provided me the following information: 1. IP address 2. Gateway address 3. Encapsulation Frame Relay 4. DLCI 100 5. BZ8 ESF (I think the bz8 was supposed to be b8zs) 6. Time Slot (1 al 24). And what I have configured up until now is the following: interface Serial0/0 ip address <ip address> 255.255.255.252 encapsulation frame-relay service-module t1 timeslots 1-24 frame-relay interface-dlci 100 sh service-module s0/0 (outputs): Module type is T1/fractional Hardware revision is 0.128, Software revision is 0.2, Image checksum is 0x73D70058, Protocol revision is 0.1 Receiver has no alarms. Framing is **ESF**, Line Code is **B8ZS**, Current clock source is line, Fraction has **24 timeslots** (64 Kbits/sec each), Net bandwidth is 1536 Kbits/sec. Last module self-test (done at startup): Passed Last clearing of alarm counters 00:17:17 loss of signal : 0, loss of frame : 0, AIS alarm : 0, Remote alarm : 2, last occurred 00:10:10 Module access errors : 0, Total Data (last 1 15 minute intervals): 0 Line Code Violations, 0 Path Code Violations 0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins 0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs Data in current interval (138 seconds elapsed): 0 Line Code Violations, 0 Path Code Violations 0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins 0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs sh int: FastEthernet0/0 is up, line protocol is up Hardware is PQUICC_FEC, address is 000d.6516.e5aa (bia 000d.6516.e5aa) Internet address is 10.0.0.1/24 MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Full-duplex, 100Mb/s, 100BaseTX/FX ARP type: ARPA, ARP Timeout 04:00:00 Last input 00:20:00, output 00:00:00, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/40 (size/max) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 0 packets input, 0 bytes Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog 0 input packets with dribble condition detected 191 packets output, 20676 bytes, 0 underruns 0 output errors, 0 collisions, 1 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier 0 output buffer failures, 0 output buffers swapped out Serial0/0 is up, line protocol is down Hardware is PQUICC with Fractional T1 CSU/DSU MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation FRAME-RELAY, loopback not set Keepalive set (10 sec) LMI enq sent 157, LMI stat recvd 0, LMI upd recvd 0, DTE LMI down LMI enq recvd 23, LMI stat sent 0, LMI upd sent 0 LMI DLCI 1023 LMI type is CISCO frame relay DTE FR SVC disabled, LAPF state down Broadcast queue 0/64, broadcasts sent/dropped 2/0, interface broadcasts 0 Last input 00:24:51, output 00:00:05, output hang never Last clearing of "show interface" counters 00:27:20 Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/1/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) Available Bandwidth 1152 kilobits/sec 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 23 packets input, 302 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 1725 input errors, 595 CRC, 1099 frame, 0 overrun, 0 ignored, 30 abort 246 packets output, 3974 bytes, 0 underruns 0 output errors, 0 collisions, 48 interface resets 0 output buffer failures, 0 output buffers swapped out 4 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up Serial0/0.1 is down, line protocol is down Hardware is PQUICC with Fractional T1 CSU/DSU MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation FRAME-RELAY Last clearing of "show interface" counters never Serial0/0.100 is down, line protocol is down Hardware is PQUICC with Fractional T1 CSU/DSU Internet address is <ip address>/30 MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation FRAME-RELAY Last clearing of "show interface" counters never And everything seems to be accounted for to me, but apparently I'm missing something. My issue is that I'm stuck on interface up, line protocol down, so the T1 doesn't go up. Any ideas? Thank you,

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• Oracle Solaris Cluster 4.2 Event and its SNMP Interface

  - by user12609115

  Background The cluster event SNMP interface was first introduced in Oracle Solaris Cluster 3.2 release. The details of the SNMP interface are described in the Oracle Solaris Cluster System Administration Guide and the Cluster 3.2 SNMP blog. Prior to the Oracle Solaris Cluster 4.2 release, when the event SNMP interface was enabled, it would take effect on WARNING or higher severity events. The events with WARNING or higher severity are usually for the status change of a cluster component from ONLINE to OFFLINE. The interface worked like an alert/alarm interface when some components in the cluster were out of service (changed to OFFLINE). The consumers of this interface could not get notification for all status changes and configuration changes in the cluster. Cluster Event and its SNMP Interface in Oracle Solaris Cluster 4.2 The user model of the cluster event SNMP interface is the same as what was provided in the previous releases. The cluster event SNMP interface is not enabled by default on a freshly installed cluster; you can enable it by using the cluster event SNMP administration commands on any cluster nodes. Usually, you only need to enable it on one of the cluster nodes or a subset of the cluster nodes because all cluster nodes get the same cluster events. When it is enabled, it is responsible for two basic tasks. • Logs up to 100 most recent NOTICE or higher severity events to the MIB. • Sends SNMP traps to the hosts that are configured to receive the above events. The changes in the Oracle Solaris Cluster 4.2 release are1) Introduction of the NOTICE severity for the cluster configuration and status change events.The NOTICE severity is introduced for the cluster event in the 4.2 release. It is the severity between the INFO and WARNING severity. Now all severities for the cluster events are (from low to high) • INFO (not exposed to the SNMP interface) • NOTICE (newly introduced in the 4.2 release) • WARNING • ERROR • CRITICAL • FATAL In the 4.2 release, the cluster event system is enhanced to make sure at least one event with the NOTICE or a higher severity will be generated when there is a configuration or status change from a cluster component instance. In other words, the cluster events from a cluster with the NOTICE or higher severities will cover all status and configuration changes in the cluster (include all component instances). The cluster component instance here refers to an instance of the following cluster componentsnode, quorum, resource group, resource, network interface, device group, disk, zone cluster and geo cluster heartbeat. For example, pnode1 is an instance of the cluster node component, and oracleRG is an instance of the cluster resource group. With the introduction of the NOTICE severity event, when the cluster event SNMP interface is enabled, the consumers of the SNMP interface will get notification for all status and configuration changes in the cluster. A thrid-party system management platform with the cluster SNMP interface integration can generate alarms and clear alarms programmatically, because it can get notifications for the status change from ONLINE to OFFLINE and also from OFFLINE to ONLINE. 2) Customization for the cluster event SNMP interface • The number of events logged to the MIB is 100. When the number of events stored in the MIB reaches 100 and a new qualified event arrives, the oldest event will be removed before storing the new event to the MIB (FIFO, first in, first out). The 100 is the default and minimum value for the number of events stored in the MIB. It can be changed by setting the log_number property value using the clsnmpmib command. The maximum number that can be set for the property is 500. • The cluster event SNMP interface takes effect on the NOTICE or high severity events. The NOTICE severity is also the default and lowest event severity for the SNMP interface. The SNMP interface can be configured to take effect on other higher severity events, such as WARNING or higher severity events by setting the min_severity property to the WARNING. When the min_severity property is set to the WARNING, the cluster event SNMP interface would behave the same as the previous releases (prior to the 4.2 release). Examples, • Set the number of events stored in the MIB to 200 # clsnmpmib set -p log_number=200 event • Set the interface to take effect on WARNING or higher severity events. # clsnmpmib set -p min_severity=WARNING event Administering the Cluster Event SNMP Interface Oracle Solaris Cluster provides the following three commands to administer the SNMP interface. • clsnmpmib: administer the SNMP interface, and the MIB configuration. • clsnmphost: administer hosts for the SNMP traps • clsnmpuser: administer SNMP users (specific for SNMP v3 protocol) Only clsnmpmib is changed in the 4.2 release to support the aforementioned customization of the SNMP interface. Here are some simple examples using the commands. Examples: 1. Enable the cluster event SNMP interface on the local node # clsnmpmib enable event 2. Display the status of the cluster event SNMP interface on the local node # clsnmpmib show -v 3. Configure my_host to receive the cluster event SNMP traps. # clsnmphost add my_host Cluster Event SNMP Interface uses the common agent container SNMP adaptor, which is based on the JDMK SNMP implementation as its SNMP agent infrastructure. By default, the port number for the SNMP MIB is 11161, and the port number for the SNMP traps is 11162. The port numbers can be changed by using the cacaoadm. For example, # cacaoadm list-params Print all changeable parameters. The output includes the snmp-adaptor-port and snmp-adaptor-trap-port properties. # cacaoadm set-param snmp-adaptor-port=1161 Set the SNMP MIB port number to 1161. # cacaoadm set-param snmp-adaptor-trap-port=1162 Set the SNMP trap port number to 1162. The cluster event SNMP MIB is defined in sun-cluster-event-mib.mib, which is located in the /usr/cluster/lib/mibdirectory. Its OID is 1.3.6.1.4.1.42.2.80, that can be used to walk through the MIB data. Again, for more detail information about the cluster event SNMP interface, please see the Oracle Solaris Cluster 4.2 System Administration Guide. - Leland Chen 

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• Organization &amp; Architecture UNISA Studies &ndash; Chap 4

  - by MarkPearl

  Learning Outcomes Explain the characteristics of memory systems Describe the memory hierarchy Discuss cache memory principles Discuss issues relevant to cache design Describe the cache organization of the Pentium Computer Memory Systems There are key characteristics of memory… Location – internal or external Capacity – expressed in terms of bytes Unit of Transfer – the number of bits read out of or written into memory at a time Access Method – sequential, direct, random or associative From a users perspective the two most important characteristics of memory are… Capacity Performance – access time, memory cycle time, transfer rate The trade off for memory happens along three axis… Faster access time, greater cost per bit Greater capacity, smaller cost per bit Greater capacity, slower access time This leads to people using a tiered approach in their use of memory   As one goes down the hierarchy, the following occurs… Decreasing cost per bit Increasing capacity Increasing access time Decreasing frequency of access of the memory by the processor The use of two levels of memory to reduce average access time works in principle, but only if conditions 1 to 4 apply. A variety of technologies exist that allow us to accomplish this. Thus it is possible to organize data across the hierarchy such that the percentage of accesses to each successively lower level is substantially less than that of the level above. A portion of main memory can be used as a buffer to hold data temporarily that is to be read out to disk. This is sometimes referred to as a disk cache and improves performance in two ways… Disk writes are clustered. Instead of many small transfers of data, we have a few large transfers of data. This improves disk performance and minimizes processor involvement. Some data designed for write-out may be referenced by a program before the next dump to disk. In that case the data is retrieved rapidly from the software cache rather than slowly from disk. Cache Memory Principles Cache memory is substantially faster than main memory. A caching system works as follows.. When a processor attempts to read a word of memory, a check is made to see if this in in cache memory… If it is, the data is supplied, If it is not in the cache, a block of main memory, consisting of a fixed number of words is loaded to the cache. Because of the phenomenon of locality of references, when a block of data is fetched into the cache, it is likely that there will be future references to that same memory location or to other words in the block. Elements of Cache Design While there are a large number of cache implementations, there are a few basic design elements that serve to classify and differentiate cache architectures… Cache Addresses Cache Size Mapping Function Replacement Algorithm Write Policy Line Size Number of Caches Cache Addresses Almost all non-embedded processors support virtual memory. Virtual memory in essence allows a program to address memory from a logical point of view without needing to worry about the amount of physical memory available. When virtual addresses are used the designer may choose to place the cache between the MMU (memory management unit) and the processor or between the MMU and main memory. The disadvantage of virtual memory is that most virtual memory systems supply each application with the same virtual memory address space (each application sees virtual memory starting at memory address 0), which means the cache memory must be completely flushed with each application context switch or extra bits must be added to each line of the cache to identify which virtual address space the address refers to. Cache Size We would like the size of the cache to be small enough so that the overall average cost per bit is close to that of main memory alone and large enough so that the overall average access time is close to that of the cache alone. Also, larger caches are slightly slower than smaller ones. Mapping Function Because there are fewer cache lines than main memory blocks, an algorithm is needed for mapping main memory blocks into cache lines. The choice of mapping function dictates how the cache is organized. Three techniques can be used… Direct – simplest technique, maps each block of main memory into only one possible cache line Associative – Each main memory block to be loaded into any line of the cache Set Associative – exhibits the strengths of both the direct and associative approaches while reducing their disadvantages For detailed explanations of each approach – read the text book (page 148 – 154) Replacement Algorithm For associative and set associating mapping a replacement algorithm is needed to determine which of the existing blocks in the cache must be replaced by a new block. There are four common approaches… LRU (Least recently used) FIFO (First in first out) LFU (Least frequently used) Random selection Write Policy When a block resident in the cache is to be replaced, there are two cases to consider If no writes to that block have happened in the cache – discard it If a write has occurred, a process needs to be initiated where the changes in the cache are propagated back to the main memory. There are several approaches to achieve this including… Write Through – all writes to the cache are done to the main memory as well at the point of the change Write Back – when a block is replaced, all dirty bits are written back to main memory The problem is complicated when we have multiple caches, there are techniques to accommodate for this but I have not summarized them. Line Size When a block of data is retrieved and placed in the cache, not only the desired word but also some number of adjacent words are retrieved. As the block size increases from very small to larger sizes, the hit ratio will at first increase because of the principle of locality, which states that the data in the vicinity of a referenced word are likely to be referenced in the near future. As the block size increases, more useful data are brought into cache. The hit ratio will begin to decrease as the block becomes even bigger and the probability of using the newly fetched information becomes less than the probability of using the newly fetched information that has to be replaced. Two specific effects come into play… Larger blocks reduce the number of blocks that fit into a cache. Because each block fetch overwrites older cache contents, a small number of blocks results in data being overwritten shortly after they are fetched. As a block becomes larger, each additional word is farther from the requested word and therefore less likely to be needed in the near future. The relationship between block size and hit ratio is complex, and no set approach is judged to be the best in all circumstances.   Pentium 4 and ARM cache organizations The processor core consists of four major components: Fetch/decode unit – fetches program instruction in order from the L2 cache, decodes these into a series of micro-operations, and stores the results in the L2 instruction cache Out-of-order execution logic – Schedules execution of the micro-operations subject to data dependencies and resource availability – thus micro-operations may be scheduled for execution in a different order than they were fetched from the instruction stream. As time permits, this unit schedules speculative execution of micro-operations that may be required in the future Execution units – These units execute micro-operations, fetching the required data from the L1 data cache and temporarily storing results in registers Memory subsystem – This unit includes the L2 and L3 caches and the system bus, which is used to access main memory when the L1 and L2 caches have a cache miss and to access the system I/O resources

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