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  • Memory mapping of files and system cache behavior in WinXP

    - by Canopus
    Our application is memory intensive and deals with reading a large number of disk files. The total load can be more than 3 GB. There is a custom memory manager that uses memory mapped files to achieve reading of such a huge data. The files are mapped into the process memory space only when needed and with this the process memory is well under control. But what is observed is, with memory mapping, the system cache keeps on increasing until it occupies the available physical memory. This leads to the slowing down of the entire system. My question is how to prevent system cache from hogging the physical memory? I attempted to remove the file buffering (by using FILE_FLAG_NO_BUFFERING ), but with this, the read operations take considerable amount of time and slows down the application performance. How to achieve the scalability without sacrificing much on performance. What are the common techniques used in such cases? I dont have a good understanding of the WinXP OS caching behavior. Any good links explaining the same would also be helpful.

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  • Why doesn't String's hashCode() cache 0?

    - by polygenelubricants
    I noticed in the Java 6 source code for String that hashCode only caches values other than 0. The difference in performance is exhibited by the following snippet: public class Main{ static void test(String s) { long start = System.currentTimeMillis(); for (int i = 0; i < 10000000; i++) { s.hashCode(); } System.out.format("Took %d ms.%n", System.currentTimeMillis() - start); } public static void main(String[] args) { String z = "Allocator redistricts; strict allocator redistricts strictly."; test(z); test(z.toUpperCase()); } } Running this in ideone.com gives the following output: Took 1470 ms. Took 58 ms. So my questions are: Why doesn't String's hashCode() cache 0? What is the probability that a Java string hashes to 0? What's the best way to avoid the performance penalty of recomputing the hash value every time for strings that hash to 0? Is this the best-practice way of caching values? (i.e. cache all except one?) For your amusement, each line here is a string that hash to 0: pollinating sandboxes amusement & hemophilias schoolworks = perversive electrolysissweeteners.net constitutionalunstableness.net grinnerslaphappier.org BLEACHINGFEMININELY.NET WWW.BUMRACEGOERS.ORG WWW.RACCOONPRUDENTIALS.NET Microcomputers: the unredeemed lollipop... Incentively, my dear, I don't tessellate a derangement. A person who never yodelled an apology, never preened vocalizing transsexuals.

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  • How do I cache jQuery selections?

    - by David
    I need to cache about 100 different selections for animating. The following is sample code. Is there a syntax problem in the second sample? If this isn't the way to cache selections, it's certainly the most popular on the interwebs. So, what am I missing? note: p in the $.path.bezier(p) below is a correctly declared object passed to jQuery.path.bezier (awesome animation library, by the way) This works $(document).ready(function() { animate1(); animate2(); }) function animate1() { $('#image1').animate({ path: new $.path.bezier(p) }, 3000); setTimeout("animate1()", 3000); } function animate2() { $('#image2').animate({ path: new $.path.bezier(p) }, 3000); setTimeout("animate2()", 3000); } This doesn't work var $one = $('#image1'); //problem with syntax here?? var $two = $('#image2'); $(document).ready(function() { animate1(); animate2(); }) function animate1() { $one.animate({ path: new $.path.bezier(p) }, 3000); setTimeout("animate1()", 3000); } function animate2() { $two.animate({ path: new $.path.bezier(p) }, 3000); setTimeout("animate2()", 3000); }

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  • "/etc/apache2/mods-enabled/proxy_html.load: Cannot load /usr/lib/libxml2.so.2 into server" error with Apache mod-proxy

    - by hhh
    The command $ sudo apt-get install libapache2-mod-proxy-html and then $sudo service apache2 restart fires: apache2: Syntax error on line 210 of /etc/apache2/apache2.conf: Syntax error on line 1 of /etc/apache2/mods-enabled/proxy_html.load: Cannot load /usr/lib/libxml2.so.2 into server: /usr/lib/libxml2.so.2: cannot open shared object file: No such file or directory Action 'configtest' failed. I am using X220 laptop. Perhaps related thing but ?AMD here. Perhaps some repeating bug in Ubuntu, again. How to fix this? Any patch yet for Ubuntu?

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  • How do i make a minecraft server mod? [closed]

    - by Simon
    Possible Duplicate: Mods for Minecraft Server - how does it work? I have made some minecraft client mods, but i've started a server a mounth ago and i want to make a mod for it, but i cant find any tutorial on the internet. How can then the other guys making those mods for minecraft server know how they are going to do? Do they try forward as i tryed or are they doing something else. I would be glad if someone could tell me how to do or find tutorials for me, couse I have tryed to find them in nearly a week of searching. But i guess im searching at the wrong spot of internet, what do i know :o

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  • How can I gain access to a player instance in a Minecraft mod?

    - by Andrew Graber
    I'm creating Minecraft mod with a pickaxe that takes away experience when you break a block. The method for taking away experience from a player is addExperience on EntityPlayer, so I need to get an instance of EntityPlayer for the player using my pickaxe when the pickaxe breaks a block, so that I can remove the appropriate amount of experience. My pickaxe class currently looks like this: public class ExperiencePickaxe extends ItemPickaxe { public ExperiencePickaxe(int ItemID, EnumToolMaterial material){ super(ItemID, material); } public boolean onBlockDestroyed(ItemStack par1ItemStack, World par2World, int par3, int par4, int par5, int par6, EntityLiving par7EntityLiving) { if ((double)Block.blocksList[par3].getBlockHardness(par2World, par4, par5, par6) != 0.0D) { EntityPlayer e = new EntityPlayer(); // create an instance e.addExperience(-1); } return true; } } Obviously, I cannot actually create a new EntityPlayer since it is an abstract class. How can I get access to the player using my pickaxe?

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  • How do I mount an HP Touchpad (Cyanogen Mod 9)?

    - by C.Werthschulte
    I've recently installed Cyanogen Mod 9 on my HP Touchpad tablet, but I'm encountering problems when trying to access it from my Ubuntu laptop (Ubuntu 11.10, Gnome-Shell, Nautilus). I've first tried accessing it via PTP as suggested here. Ubuntu will recognize the Touchpad as a digicam and only grant me access to two directories: "DCIM" and "Pictures". I then tried accessing the tablet via MTP using this post on OMGUbuntu!. Ubuntu will connect to the tablet, but only grant me access to a folder named "Playlists". I'm a bit clueless as to what I'm doing wrong and would very much appreciate any help or hints. Many thanks!

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  • Sharing files with Android devices (How do I mount an HP Touchpad, Cyanogen Mod 9?)

    - by C.Werthschulte
    I've recently installed Cyanogen Mod 9 on my HP Touchpad tablet, but I'm encountering problems when trying to access it from my Ubuntu laptop (Ubuntu 11.10, Gnome-Shell, Nautilus). I've first tried accessing it via PTP as suggested here. Ubuntu will recognize the Touchpad as a digicam and only grant me access to two directories: "DCIM" and "Pictures". I then tried accessing the tablet via MTP using this post on OMGUbuntu!. Ubuntu will connect to the tablet, but only grant me access to a folder named "Playlists". I'm a bit clueless as to what I'm doing wrong and would very much appreciate any help or hints. Many thanks!

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  • Ubuntu 13.10 on SSD (system) and HDD (data). Missing /grub/i386-pc/normal.mod

    - by Tatarkow
    I've got HDD (750 GB) and SSD (16 GB). I want to install Ubuntu (13.10) on SSD, but because of its smallness I need to install /home, /var and /tmp on HDD. After that I would like to install Windows (system + data) on another partition of that HDD, but it is not important now. I installed Ubuntu (I had formatted and partitioned the disk before), but when I restarted my laptop it said: 'error: file '/grub/i386-pc/normal.mod' not found. grub rescue'. I tried to reinstall Grub 2 using this tutorial (as sdXY I used sdb1, because it's the only one partion of my SSD), but it didn't work. Can anybody help me, please? Thanks, Tatarkow

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  • Hibernate database integrity with multiple java applications

    - by Austen
    We have 2 java web apps both are read/write and 3 standalone java read/write applications (one loads questions via email, one processes an xml feed, one sends email to subscribers) all use hibernate and share a common code base. The problem we have recently come across is that questions loaded via email sometimes overwrite questions created in one of the web apps. We originally thought this to be a caching issue. We've tried turning off the second level cache, but this doesn't make a difference. We are not explicitly opening and closing sessions, but rather let hibernate manage them via Util.getSessionFactory().getCurrentSession(), which thinking about it, may actually be the issue. We'd rather not setup a clustered 2nd level cache at this stage as this creates another layer of complexity and we're more than happy with the level of performance we get from the app as a whole. So does implementing a open-session-in-view pattern in the web apps and manually managing the sessions in the standalone apps sound like it would fix this? Or any other suggestions/ideas please? <property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property> <property name="hibernate.current_session_context_class">thread</property> <property name="hibernate.cache.use_second_level_cache">false</property>

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  • What should the name of this class be?

    - by Tim Murphy
    Naming classes is sometimes hard. What do you think name of the class should be? I originally created the class to use as a cache but can see its may have other uses. Example code to use the class. Dim cache = New NamePendingDictionary(Of String, Sample) Dim value = cache("a", Function() New Sample()) And here is the class that needs a name. ''' <summary> ''' Enhancement of <see cref="System.Collections.Generic.Dictionary"/>. See the Item property ''' for more details. ''' </summary> ''' <typeparam name="TKey">The type of the keys in the dictionary.</typeparam> ''' <typeparam name="TValue">The type of the values in the dictionary.</typeparam> Public Class NamePendingDictionary(Of TKey, TValue) Inherits Dictionary(Of TKey, TValue) Delegate Function DefaultValue() As TValue ''' <summary> ''' Gets or sets the value associated with the specified key. If the specified key does not exist ''' then <paramref name="createDefaultValue"/> is invoked and added to the dictionary. The created ''' value is then returned. ''' </summary> ''' <param name="key">The key of the value to get.</param> ''' <param name="createDefaultValue"> ''' The delegate to invoke if <paramref name="key"/> does not exist in the dictionary. ''' </param> ''' <exception cref="T:System.ArgumentNullException"><paramref name="key" /> is null.</exception> Default Public Overloads ReadOnly Property Item(ByVal key As TKey, ByVal createDefaultValue As DefaultValue) As TValue Get Dim value As TValue If createDefaultValue Is Nothing Then Throw New ArgumentNullException("createValue") End If If Not Me.TryGetValue(key, value) Then value = createDefaultValue.Invoke() Me.Add(key, value) End If Return value End Get End Property End Class

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  • Making IE "forget" information entered in form when using back button.

    - by typoknig
    I have a page with a form where many of the fields are populated from variables passed in the URL. Those fields are disabled (NON-EDITABLE) and are only there for the user to view. The remaining fields require user input and are NOT disabled (EDITABLE). When the form is submitted a confirmation page comes up. It may be the case that the user needs to submit several of these forms where the NON-EDITABLE information is identical from form to form, so being able to go back to the form page from the confirmation page would save a lot of time. The way I want this to work is when a user presses the back button all the NON-EDITABLE fields are populated, but the EDITABLE fields are blank. This is what Firefox is doing, but IE8 is does not "forget" what has been entered in the EDITABLE fields. To disable the cache the following appears at the beginning of my page AND at the end of my page. <head> <meta http-equiv="Pragma" content="no-cache"/> <meta http-equiv="Cache-Control" content="no-store"/> <head/> What more must I do to make IE forget what was entered in the EDITABLE fields when the back button is pressed? All of my pages are generated with PHP if that matters. EDIT: It appears to me that this is a problem of IE caching my page even though I have told it not to. Are my meta tags correct? Do I need to do something else to prevent IE from caching my page?

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  • Cannot ping host stale ARP cache?

    - by gkchicago
    I am having a strange issue with a Debian (Lenny/Linux 2.6.26-2-amd64) that has been driving me nuts. On some machines within my network I can ping the host in question just fine, other times I have to manually hard-code the ARP ethernet address for the IP in order to establish connectivity. I've finally worked it down to somehow involving ARP. I just found how to fix it in a way that made it work but I'm looking for help explaining this issue and also I don't trust my fix to be permanent.. My thought process has been the following but I just can't make any sense out of it: Could it be the card? (Intel 82555 rev 4) Could it be because there are two network cards? (Default route is eth0) Could it be because of the network aliases? Lenny? AMD x86_64? Argh.. Thank you for any insight you might have // Ping doesn't go thru [gordon@ubuntu ~]$ ping 192.168.135.101 PING 192.168.135.101 (192.168.135.101) 56(84) bytes of data. --- 192.168.135.101 ping statistics --- 4 packets transmitted, 0 received, 100% packet loss, time 3014ms // Here's the ARP Table, sometimes the .151 address is good, sometimes it // also matches the Gateways MAC like .101 is doing right here. [gordon@ubuntu ~]$ cat /proc/net/arp IP address HW type Flags HW address Mask Device 192.168.135.15 0x1 0x2 00:0B:DB:2B:24:89 * eth0 192.168.135.151 0x1 0x2 00:0B:6A:3A:30:A6 * eth0 192.168.135.1 0x1 0x2 00:1A:A2:2D:2A:04 * eth0 192.168.135.101 0x1 0x2 00:1A:A2:2D:2A:04 * eth0 // Drop the bad arp table listing and set it manually based on /sbin/ifconfig [gordon@ubuntu ~]$ sudo arp -d 192.168.135.101 [gordon@ubuntu ~]$ sudo arp -s 192.168.135.101 00:0B:6A:3A:30:A6 // Ping starts going thru..?!? [gordon@ubuntu ~]$ ping 192.168.135.101 PING 192.168.135.101 (192.168.135.101) 56(84) bytes of data. 64 bytes from 192.168.135.101: icmp_seq=1 ttl=64 time=15.8 ms 64 bytes from 192.168.135.101: icmp_seq=2 ttl=64 time=15.9 ms 64 bytes from 192.168.135.101: icmp_seq=3 ttl=64 time=16.0 ms 64 bytes from 192.168.135.101: icmp_seq=4 ttl=64 time=15.9 ms --- 192.168.135.101 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3012ms rtt min/avg/max/mdev = 15.836/15.943/16.064/0.121 ms The following is my network config on this. gordon@db01:~$ /sbin/ifconfig eth0 Link encap:Ethernet HWaddr 00:0b:6a:3a:30:a6 inet addr:192.168.135.151 Bcast:192.168.135.255 Mask:255.255.255.0 inet6 addr: fe80::20b:6aff:fe3a:30a6/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:15476725 errors:0 dropped:0 overruns:0 frame:0 TX packets:10030036 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:18565307359 (17.2 GiB) TX bytes:3412098075 (3.1 GiB) eth0:0 Link encap:Ethernet HWaddr 00:0b:6a:3a:30:a6 inet addr:192.168.135.150 Bcast:192.168.135.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 eth0:1 Link encap:Ethernet HWaddr 00:0b:6a:3a:30:a6 inet addr:192.168.135.101 Bcast:192.168.135.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 eth1 Link encap:Ethernet HWaddr 00:e0:81:2a:6e:d0 inet addr:10.10.62.1 Bcast:10.10.62.255 Mask:255.255.255.0 inet6 addr: fe80::2e0:81ff:fe2a:6ed0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:10233315 errors:0 dropped:0 overruns:0 frame:0 TX packets:19400286 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1112500658 (1.0 GiB) TX bytes:27952809020 (26.0 GiB) Interrupt:24 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:387 errors:0 dropped:0 overruns:0 frame:0 TX packets:387 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:41314 (40.3 KiB) TX bytes:41314 (40.3 KiB) gordon@db01:~$ sudo mii-tool -v eth0 eth0: negotiated 100baseTx-FD, link ok product info: Intel 82555 rev 4 basic mode: autonegotiation enabled basic status: autonegotiation complete, link ok capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD advertising: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD gordon@db01:~$ sudo route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface localnet * 255.255.255.0 U 0 0 0 eth0 10.10.62.0 * 255.255.255.0 U 0 0 0 eth1 default 192.168.135.1 0.0.0.0 UG 0 0 0 eth0

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  • Does MS Forefront TMG cache authentication?

    - by SnOrfus
    I'm testing a client machine that makes requests to a biztalk server using a forefront machine as a web proxy. Upon first test I put in an invalid name/password into the receive port and received the correct error message (407). Then, I set the correct name/password and everything worked correctly. From there, I kept the correct information in the receive port but put an invalid name/password into the send adapter but the process completed successfully (should have failed with 407). I've ensured that both the recieve and send ports are not bypassing the proxy for local addresses. So the only thing that seems to make sense is if TMG is caching the authentication request coming from the machine I'm working on. Is this thinking correct, and if so, does anyone know how to disable it in TMG?

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  • When DNS doesn't cache

    - by John Francis
    We've had some odd DNS problems over the past couple of days that I don't fully understand. Some of our DNS names stopped resolving for some of our customers due to some 'unknown' server reconfiguration at our DNS provider. The problem seemed to be intermittent i.e. stopped working and started working within a few minutes over a couple of days. I'm no expert on DNS, but I'd have expected DNS caches to prevent this sort of thing from happening - when we need to change an IP address for a DNS record, it can take 24 hours to propogate, so how can our DNS provider be breaking name resolution intermittently for our customers so easily? Shouldn't the DNS caches kick in here? We had a similar problem about a month ago when one of their nameservers 'decided to reload the DNS database from scratch' - this broke our name resolution too. Again, why didn't the caches satisfy the name resolution requests. Any guesses would be appreciated. John

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  • How does NFS read cache work on Debian?

    - by Ztyx
    I am planning to use NFS to serve out many small files. They will be read very often so client side caching is crucial. Does NFS handle this? Is there a way to increase the client side caching in some way? ...or should I look at another solution? Syncing using rsync or unison periodically is not an option since the files are modified on the client side from time to time.

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  • Transpose matrix-style table to 3 columns in Excel

    - by polarbear2k
    I have a matrix-style table in excel where B1:Z1 are column headings and A2:A99 are row headings. I would like to convert this table to a 3 column table (column heading, row heading, cell value). It does not matter in what order the new table is. A B C D A B C A B C 1 H1 H2 H3 1 H1 R1 V1 1 H1 R1 V1 2 R1 V1 V2 V3 => 2 H1 R2 V4 or 2 H2 R1 V2 3 R2 V4 V5 V6 3 H1 R3 V7 3 H3 R1 V3 4 R3 V7 V8 V9 4 H2 R1 V2 4 H1 R2 V4 5 H2 R2 V5 5 H2 R2 V5 6 H2 R3 V8 6 H3 R2 V6 7 H3 R1 V3 7 H1 R3 V7 8 H3 R2 V6 8 H2 R3 V8 9 H3 R3 V9 9 H3 R3 V8 I've been playing around with the OFFSET function to create the whole table but I feel like a combination of TRANSPOSE and V/HLOOKUP is required. Thanks EDIT I have managed to come up with the correct formulas. If the data is in Sheet1 like in my example above, the formulas go in Sheet2: [A1] =IF(ROW() <= COUNTA(Sheet1!$B$1:$Z$1)*COUNTA(Sheet1!$A$2:$A$99), OFFSET(Sheet1!$A$1,0,IF(MOD(ROW(),COUNTA(Sheet1!$B$1:$Z$1))=0,COUNTA(Sheet1!$B$1:$Z$1),MOD(ROW(),COUNTA(Sheet1!$B$1:$Z$1)))),"") [B1] =IF(ROW() <= COUNTA(Sheet1!$B$1:$Z$1)*COUNTA(Sheet1!$A$2:$A$99),OFFSET(Sheet1!$A$1,IF(MOD(ROW(),COUNTA(Sheet1!$A$2:$A$99))=0,COUNTA(Sheet1!$A$2:$A$99),MOD(ROW(),COUNTA(Sheet1!$A$2:$A$99))),0),"") [C1] =IF(ROW() <= COUNTA(Sheet1!$B$1:$Z$1)*COUNTA(Sheet1!$A$2:$A$99),OFFSET(Sheet1!$A$1,IF(MOD(ROW(),COUNTA(Sheet1!$A$2:$A$99))=0,COUNTA(Sheet1!$A$2:$A$99),MOD(ROW(),COUNTA(Sheet1!$A$2:$A$99))),IF(MOD(ROW(),COUNTA(Sheet1!$B$1:$Z$1))=0,COUNTA(Sheet1!$B$1:$Z$1),MOD(ROW(),COUNTA(Sheet1!$B$1:$Z$1)))),"") The formulas are limited to B1:Z1 for the headings and A2:A99 for the rows (these can be increased to their maximums if required). The COUNTA() formula returns the number of cells that actually have values, which limits the number of rows returned to headings*rows. Otherwise the formulas would could go on for infinity because of the MOD function.

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  • Centos swap cache memory leak

    - by user30008
    We have a image server that keeps running out of memory and crashing, we thought there was a hardware issue with the machine because the code base has not changed and this is a new issue. We brought a new machine online with newer kernel and fresh centos 5.4 install and just brought online one subdomain and the exact same error is occurring on the new machine. How should I try and troubleshoot this issue.

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  • Varnish : Non-Cache/Data Fetch + Load-Balance

    - by xperator
    Someone commented at my previous question and said it's possible to do this with Varnish: Instead of : Client Request Varnish LB Backend Varnish LB Client I want to have (Direct reply from backend to client, instead of going through the LB) : Client Request Varnish LB Backend Client This is not working : sub vcl_pass { if (req.http.host ~ "^(www.)?example.com$") { set req.backend = baz; return (pass); } }

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  • Disqus cache of unposted posts

    - by user129107
    Some webpages implement Disqus and also have the rather bad policy of adding auto refresh to the page. This result in for example one writing a long answer in a debate and then a refresh comes along – and everything is gone. Is the comments, written, but not posted, cached somewhere? Is it possible to retrieve? I have experienced this on various pages. In the current case the debate page was reloaded and a rather lengthy post with a lot of references and long thought out sentences vanished. This page closes the debate during night time, and do a auto refresh of the page when one pass midnight – as such I'm not able to retrieve the debate for another 8 hours. Other pages implement for example an auto refresh after 20 minutes. Linux, Google Chrome.

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  • How to utilize Varnish for A/B Testing and Feature Rollout?

    - by Ken
    Hi all, wasn't really sure if this should go here on or stackoverlow - admins, please move if i'm mistaken (and sorry). Today we have our web layer exposed to the world. We would like to add Varnish in front of our web layer to accelerate the site and reduce calls to the backend. However, we have some concerns and i was wondering how most people approach them: A/B Testing - How do you test two "versions" of each page and compare? I mean, how does varnish know which page to serve up? If and how do you save seperate versions on each page? Feature rollout - how would you set up a simple feature rollout mechanism? Let's say i want to open a new feature/page to just 10% of the traffic.. and then later increase that to 20%? How do you handle code deployments? Do you purge your entire varnish cache every deployment? (We have deployments on a daily basis). Or do you just let it slowly expire (using TTL)? Any ideas and examples regarding these issues is greatly appreciated! Thanks in advance. Ken.

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  • ZFS with L2ARC (SSD) slower for random seeks than without L2ARC

    - by Florian Kruse
    I am currently testing ZFS (Opensolaris 2009.06) in an older fileserver to evaluate its use for our needs. Our current setup is as follows: Dual core (2,4 GHz) with 4 GB RAM 3x SATA controller with 11 HDDs (250 GB) and one SSD (OCZ Vertex 2 100 GB) We want to evaluate the use of a L2ARC, so the current ZPOOL is: $ zpool status pool: tank state: ONLINE scrub: none requested config: NAME STATE READ WRITE CKSUM afstank ONLINE 0 0 0 raidz1 ONLINE 0 0 0 c11t0d0 ONLINE 0 0 0 c11t1d0 ONLINE 0 0 0 c11t2d0 ONLINE 0 0 0 c11t3d0 ONLINE 0 0 0 raidz1 ONLINE 0 0 0 c13t0d0 ONLINE 0 0 0 c13t1d0 ONLINE 0 0 0 c13t2d0 ONLINE 0 0 0 c13t3d0 ONLINE 0 0 0 cache c14t3d0 ONLINE 0 0 0 where c14t3d0 is the SSD (of course). We run IO tests with bonnie++ 1.03d, size is set to 200 GB (-s 200g) so that the test sample will never be completely in ARC/L2ARC. The results without SSD are (average values over several runs which show no differences) write_chr write_blk rewrite read_chr read_blk random seeks 101.998 kB/s 214.258 kB/s 96.673 kB/s 77.702 kB/s 254.695 kB/s 900 /s With SSD it becomes interesting. My assumption was that the results should be in worst case at least the same. While write/read/rewrite rates are not different, the random seek rate differs significantly between individual bonnie++ runs (between 188 /s and 1333 /s so far), average is 548 +- 200 /s, so below the value w/o SSD. So, my questions are mainly: Why do the random seek rates differ so much? If the seeks are really random, they should not differ much (my assumption). So, even if the SSD is impairing the performance it should be the same in each bonnie++ run. Why is the random seek performance worse in most of the bonnie++ runs? I would assume that some part of the bonnie++ data is in the L2ARC and random seeks on this data performs better while random seeks on other data just performs similarly like before.

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  • iptables secure squid proxy

    - by Lytithwyn
    I have a setup where my incoming internet connection feeds into a squid proxy/caching server, and from there into my local wireless router. On the wan side of the proxy server, I have eth0 with address 208.78.∗∗∗.∗∗∗ On the lan side of the proxy server, I have eth1 with address 192.168.2.1 Traffic from my lan gets forwarded through the proxy transparently to the internet via the following rules. Note that traffic from the squid server itself is also routed through the proxy/cache, and this is on purpose: # iptables forwarding iptables -A FORWARD -i eth1 -o eth0 -s 192.168.2.0/24 -m state --state NEW -j ACCEPT iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A POSTROUTING -t nat -j MASQUERADE # iptables for squid transparent proxy iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j DNAT --to 192.168.2.1:3128 iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3128 How can I set up iptables to block any connections made to my server from the outside, while not blocking anything initiated from the inside? I have tried doing: iptables -A INPUT -i eth0 -s 192.168.2.0/24 -j ACCEPT iptables -A INPUT -i eth0 -j REJECT But this blocks everything. I have also tried reversing the order of those commands in case I got that part wrong, but that didn't help. I guess I don't fully understand everything about iptables. Any ideas?

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  • Caching/preloading files on Linux into RAM

    - by Andrioid
    I have a rather old server that has 4GB of RAM and it is pretty much serving the same files all day, but it is doing so from the hard drive while 3GBs of RAM are "free". Anyone who has ever tried running a ram-drive can witness that It's awesome in terms of speed. The memory usage of this system is usually never higher than 1GB/4GB so I want to know if there is a way to use that extra memory for something good. Is it possible to tell the filesystem to always serve certain files out of RAM? Are there any other methods I can use to improve file reading capabilities by use of RAM? More specifically, I am not looking for a 'hack' here. I want file system calls to serve the files from RAM without needing to create a ram-drive and copy the files there manually. Or at least a script that does this for me. Possible applications here are: Web servers with static files that get read alot Application servers with large libraries Desktop computers with too much RAM Any ideas? Edit: Found this very informative: The Linux Page Cache and pdflush As Zan pointed out, the memory isn't actually free. What I mean is that it's not being used by applications and I want to control what should be cached in memory.

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