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  • What is the best memory supported by Asus Rampage Formula (1) motherboard

    - by James
    I'm rebuilding a PC from old components I have and I want to know what are the best ram sticks for the Asus Rampage Formula (The first motherboard in the Rampage Formula range) According to the Asus website (HERE) the maximum supported memory is 8GB but when I search through the memory compatibility list there's nothing above 2046mb and the motherboard only supports single or dual-channel memory. Can anyone point me in the direction of a more comprehensive list of compatible memory? Or does anyone know where I can ask about memory compatibility? Note: As far as I know, this model motherboard is no longer in production.

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  • tweak windows 7 virtual memory and cache / caching settings

    - by bortao
    im on windows 7 64 bit, with 4gb of memory whenever i copy or deal with a big ammount of data, windows swaps out everything from memory to the virtual memory swapfile, to make room to data cache. the problem is: i dont really need caching of this data im copying, its being copied only once, cacheing this data won't help me. on the other hand, swapping out the programs will give me a big lag time whenever i want to use those open programs again. what i want: restrict data cache to a certain ammount, lets say 1gb, or reserve a certain ammount of memory, lets say 2gb, exclusively for running programs memory. my swap file is on a separate partition, but i still have problems with swapping time.

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  • tweak windows 7 virtual memory and cache / caching settings

    - by bortao
    im on windows 7 64 bit, with 4gb of memory whenever i copy or deal with a big ammount of data, windows swaps out everything from memory to the virtual memory swapfile, to make room to data cache. the problem is: i dont really need caching of this data im copying, its being copied only once, cacheing this data won't help me. on the other hand, swapping out the programs will give me a big lag time whenever i want to use those open programs again. what i want: restrict data cache to a certain ammount, lets say 1gb, or reserve a certain ammount of memory, lets say 2gb, exclusively for running programs memory. my swap file is on a separate partition, but i still have problems with swapping time.

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  • Why do I not get low memory issues until images are draw on the screen?

    - by maxpower
    I am able to load over 200 UIImage objects into a NSMutableDictionary without any memorry warning issues. When I start displaying them on the screen (after about showing 10-20 images) I get low memory warnings and an eventual crash. Only about 8 images are displayed at anyone time. Does it take additional memory to actually draw a UIImage on the screen? No memory leaks are showing up and i've reviewed code for leaks many many times.

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  • Out Of Memory Error - Magento

    - by robobobobo
    Ok normally I understand when my server is giving me out of memory errors, but this one has me stumped! I'm running a magento based site, with one or two plugins in it and the rest is pretty basic. The site runs and loads fine wiht no issues. However in the backend - Configuration - Payment Methods it gives me the following out of memory error Fatal error: Out of memory (allocated 39059456) (tried to allocate 85 bytes) in ########/Varien/Simplexml/Element.php on line 84 Now this is where I'm confused..it's allocated more than it tried to allocate? Am I correct there? So how is it running out of memory? My server has 6Gb ram, an SSD and 2 CPU's running WHM with a few other low traffic sites on it. I set my php memory limit to 100mb, 1000mb and finally unlimited but all to no avail! I'm completely lost here, would really appreciate some expertise on this Cheers

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  • Any useful suggestions to figure out where memory is being free'd in a Win32 process?

    - by LeopardSkinPillBoxHat
    An application I am working with is exhibiting the following behaviour: During a particular high-memory operation, the memory usage of the process under Task Manager (Mem Usage stat) reaches a peak of approximately 2.5GB (Note: A registry key has been set to allow this, as usually there is a maximum of 2GB for a process under 32-bit Windows) After the operation is complete, the process size slowly starts decreasing at a rate of 1MB per second. I am trying to figure out the easiest way to quickly determine who is freeing this memory, and where it is being free'd. I am having trouble attaching a memory profiler to my code, and I don't particularly want to override the new/delete operators to track the allocations/deallocations (IOW, I want to do this without re-compiling my code). Can anyone offer any useful suggestions of how I could do this via the Visual Studio debugger? Update I should also mention that it's a multi-threaded application, so pausing the application and analysing the call stack through the debugger is not the most desirable option. I considered freezing different threads one at a time to see if the memory stops reducing, but I'm fairly certain this will cause the application to crash.

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  • /dev/shm (shared memory) on linux

    - by Kirzilla
    Hello, Let's imagine that we have 8Gb of RAM on server. I'm mounting /dev/shm with 4Gb on board. mount -o remount,size=4G /dev/shm Will this memory be strictly reserved for shared memory or if /dev/shm is empty this memory could be used by regular applications (web server, php etc.)? PS:Sorry for my English. I'm asking it because I've just checked df -h and found tmpfs 6.0G 0 6.0G 0% /dev/shm on 8Gb RAM sever. I don't know who made this setup, but it seems to me awful. Thank you!

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  • Apache with mod_perl eating memory when idle

    - by syneticon-dj
    An Apache webserver running a mod_perl application is exposing abnormal memory usage - after the "day load" ceases, the system's memory is being exhausted by the Apache processes and oom_killer is being invoked. As the load returns the following morning, the memory usage normalizes - probably because Apache workers get recycled periodically if a sufficient number of hits is generated: This is the graph for apache hits per second to correlate: The remaining 2 hits per second throughout the night are induced by HAProxy checks - it runs HEAD http://mydomain.example.com/running HTTP/1.0 requests against the server every half a second with "running" being a static file (i.e. not invoking any perl code). It also seems that disabling these checks remedies the memory usage problem, but obviously cannot be a solution. All of 3 similarly configured servers (behind HAProxy) expose this behavior. The running OS is Ubuntu 10.10, Apache version 2.2.16. This seems to be a memory leak but I have no idea how to start debugging it - any hints?

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  • windows 2008 r2 iis worker proccess memory usage increase

    - by nLL
    I have this web site written in c#. around 400-500 users online at any time. it was on windows 2008 32 bit machine before and never ever locked/slowed down due to increased memory consumption up until i upgraded it's server to win 2008 r2 64 bit. Old server had only 4 gig ram and quad core cpu at 2ghz. site was working just fine. since i've upgraded the server i noticed (2 times with in 10 days) it started to eat ram. last night it went up to 4 gb ram. with ram increase response slows down quite a lot. recycling app pool doesn't help. I have to restart it's worker process to recover. i've noticed this usually happens if there are continuous errors. as i didn't change anything in the code am i safe to assume it is not related to memory leak in the code? did anyone came across something like that? same thing happens if i create continuous errors with classic asp. thanks

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  • How to monitor broadband usage on gateway.2wire Router

    - by Paul
    I have a gateway.2wire router from BT (model: BT2700HGV). My home network has a number of internet devices (PCs, game consoles, ipod touch etc) Is there anyway to get monthly internet usage stats from the router? The ISP (BT) will not give you these stats, they will only tell you when you go over your limit.

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  • Free tool for monitoring Broadband usage on Windows 7

    - by Sharjeel Sayed
    I need a free tool ( non browser ) to monitor my broadband usage on Windows 7 since my ISP has placed a cap on monthly downloads. I need a PC based solution since I use a USB router to connect to the internet.All other solutions I found were router/network based and also wasn't sure of all the freeware tools I found on Google to do this job.Need suggestions personal experiences.

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  • Low CPU usage but High fan speed

    - by dhasu
    The problem I am facing is the CPU fan rotates with high speed even though the CPU usage is very low, less than 10%. I even cleaned the Dust off the Fan, I replaced the Thermal Material on the Processor. Installed an Extra Fan. Nothing seems to Work. Please Help.

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  • Reason behind system power usage?

    - by user28565
    Hi, when the number of applications running in a pc increases, the power consumed by the PC is also increasing. Is this correct? I think the reason behind this is CPU. Please let me know what role the CPU plays for more power usage. Thanks, Kavi

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  • What is private bytes, virtual bytes, working set?

    - by Devil Jin
    I am using perfmon windows utility to debug memory leak in a process. Perfmon explaination: Working Set- Working Set is the current size, in bytes, of the Working Set of this process. The Working Set is the set of memory pages touched recently by the threads in the process. If free memory in the computer is above a threshold, pages are left in the Working Set of a process even if they are not in use. When free memory falls below a threshold, pages are trimmed from Working Sets. If they are needed they will then be soft-faulted back into the Working Set before leaving main memory. Virtual Bytes- Virtual Bytes is the current size, in bytes, of the virtual address space the process is using. Use of virtual address space does not necessarily imply corresponding use of either disk or main memory pages. Virtual space is finite, and the process can limit its ability to load libraries. Private Bytes- Private Bytes is the current size, in bytes, of memory that this process has allocated that cannot be shared with other processes. Q1. Is it the private byte should I measure to be sure if the process is having any leak as it does not involve any shared libraries and any leak if happening will be coming from the process itself? Q2. What is the total memory consumed by the process? Is it the Virtual byte size? or Is it the sum of Virtual Bytes and Working Set Q3. Is there any relation between private bytes, working set and virtual bytes. Q4. Any tool which gives a better idea memory information?

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  • Locating memory leak in Apache httpd process, PHP/Doctrine-based application

    - by Sam
    I have a PHP application using these components: Apache 2.2.3-31 on Centos 5.4 PHP 5.2.10 Xdebug 2.0.5 with Remote Debugging enabled APC 3.0.19 Doctrine ORM for PHP 1.2.1 using Query Caching and Results Caching via APC MySQL 5.0.77 using Query Caching I've noticed that when I start up Apache, I eventually end up 10 child processes. As time goes on, each process will grow in memory until each one approaches 10% of available memory, which begins to slow the server to a crawl since together they grow to take up 100% of memory. Here is a snapshot of my top output: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1471 apache 16 0 626m 201m 18m S 0.0 10.2 1:11.02 httpd 1470 apache 16 0 622m 198m 18m S 0.0 10.1 1:14.49 httpd 1469 apache 16 0 619m 197m 18m S 0.0 10.0 1:11.98 httpd 1462 apache 18 0 622m 197m 18m S 0.0 10.0 1:11.27 httpd 1460 apache 15 0 622m 195m 18m S 0.0 10.0 1:12.73 httpd 1459 apache 16 0 618m 191m 18m S 0.0 9.7 1:13.00 httpd 1461 apache 18 0 616m 190m 18m S 0.0 9.7 1:14.09 httpd 1468 apache 18 0 613m 190m 18m S 0.0 9.7 1:12.67 httpd 7919 apache 18 0 116m 75m 15m S 0.0 3.8 0:19.86 httpd 9486 apache 16 0 97.7m 56m 14m S 0.0 2.9 0:13.51 httpd I have no long-running scripts (they all terminate eventually, the longest being maybe 2 minutes long), and I am working under the assumption that once each script terminates, the memory it uses gets deallocated. (Maybe someone can correct me on that). My hunch is that it could be APC, since it stores data between requests, but at the same time, it seems weird that it would store data inside the httpd process. How can I track down which part of my app is causing the memory leak? What tools can I use to see how the memory usage is growing inside the httpd process and what is contributing to it?

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  • Windows memory logged on vs logged off

    - by Adi
    Let's say I power on my fresh installed Windows 7 x64 machine. After Windows boots up, there are a bunch of services being started in the background that start allocating memory. Then I enter my user/pass and Windows logs me in. Let's supose I don't do anythig else (I don't explicitely start any application) and I don't have any other app installed by me. So it's fresh install of my machine. My question is: how much memory is needed for all the UI & other stuff? Is it a good indicator to look into task manager and check all the processes started under my user name and sum up all the memory consumed by those processes to get the total amount of memory I am consuming just to stay logged on? Basically this is my question: how much memory is needed just to stay logged on? Now, if log off would all the memory be released back to the system so that the background services can benefit of? Also, I assume that there might be a different discussion for each Windows flavors (?)

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  • Ubuntu: Memory Leak

    - by Keener
    I'm having trouble finding from where this memory leak is occurring. I'm running Ubuntu 8.04 LTS on a Dell XPS M1530. I have 3GB of ram and I'm finding after about an hour or so of use top shows me 2GBs+ used. The strange thing is when I add up the memory percentages by PID either from top or ps aux I find that I should only be using about 20-25% of my available ram. What brought this to my attention was I've begun running vmware server again. Now, obviously the ram usage spikes when I load a virtual machine, but the memory VMware is using does not account for the memory usage I'm seeing via top or free. Stopping vmware server releases the memory which was allocated to it, but I'm still unable to find where this RAM is being used. After a complete reboot, of course, the memory is fine, but very quickly it climbs to 60-80% usage with the processes only appearing to account for a third of that. Any ideas where I should look for more information on what this could be?

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  • Missing Memory on Windows Server 2008

    - by Chris Lively
    I have a windows 2008 x64 server with 8GB of RAM installed. Task Manager and Resource Monitor both insist that 7.5GB of the RAM is in use. However, the memory list under Processes (Memory Private Bytes) doesn't add up. I do have Show Processes from all users checked and hand adding the numbers I come up with about 3.5GB of RAM. I also looked at the latest copy of SysInternals Process Explorer. And neither the Private Bytes or Working Set adds up to more than about 3.5GB of RAM in use. What's going on? ===== Update: I bounced the server to see what would happen with the memory utilization. After boot and regular operations began it sat at 3GB of RAM usage. 18 hours later, it's back up to 6.8GB of usage with no indication as to where the additional 3.5GB or so of RAM is being used. Here are links to screen shots of the resource monitor and task manager: Resource Monitor Task Manager Update 2: Well, I believe I located the problem. When I detached one of the larger databases from my sql server the amount of ram shown as "in use" dropped drastically. The Memory Private Bytes count barely moved. So I'm guessing that SQL server has some way of allocating memory where it doesn't really show up in any of the monitors. I went further and created a new database file, then transferred all of the data from the one I detached. Even though it has the same data, and the same transactions going through it, the memory in use has stayed low. Maybe there was some corruption in the DB? I'll leave it to the DB gods and go searching for another "problem" ;)

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  • Determining how all memory is used in Windows Server 2008

    - by Mojah
    Hi, I have a Windows Server 2008 system, which has 12GB of RAM. If I list all processes in the Task Manager, and SUM() the memory of each process (Working Set, Memory (Private Working Set), Commit Size, ...), I never reach more than 4-5GB that should be "in use". However, task manager reports this server has 11GB in use via the "Performance" tab. I'm failing in determining where all that used RAM is going. It doesn't seem to be system cache, but I can not be sure. It might be a memory leak in one of the appliances, but I'm struggling to find out which one. The server's memory keeps filing up, and eventually forces us to reboot the device to clear it. I've been reading up on how RAM assignments work on Windows Server: RAM, Virtual Memory, Pagefile and all that stuff: http://support.microsoft.com/kb/2267427 What's the best way to measure? http://www.zdnet.com/blog/bott/windows-7-memory-usage-whats-the-best-way-to-measure/1786 Configure the file system cache in Windows: http://smallvoid.com/article/winnt-system-cache.html But I fear I'm stuck without ideas at the moment.

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  • Determining how all memory is used in Windows Server 2008

    - by Mojah
    I have a Windows Server 2008 system, which has 12GB of RAM. If I list all processes in the Task Manager, and SUM() the memory of each process (Working Set, Memory (Private Working Set), Commit Size, ...), I never reach more than 4-5GB that should be "in use". However, task manager reports this server has 11GB in use via the "Performance" tab. I'm failing in determining where all that used RAM is going. It doesn't seem to be system cache, but I can not be sure. It might be a memory leak in one of the appliances, but I'm struggling to find out which one. The server's memory keeps filing up, and eventually forces us to reboot the device to clear it. I've been reading up on how RAM assignments work on Windows Server: RAM, Virtual Memory, Pagefile and all that stuff: http://support.microsoft.com/kb/2267427 What's the best way to measure? http://www.zdnet.com/blog/bott/windows-7-memory-usage-whats-the-best-way-to-measure/1786 Configure the file system cache in Windows: http://smallvoid.com/article/winnt-system-cache.html But I fear I'm stuck without ideas at the moment.

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  • Plan Caching and Query Memory Part I – When not to use stored procedure or other plan caching mechanisms like sp_executesql or prepared statement

    - by sqlworkshops
      The most common performance mistake SQL Server developers make: SQL Server estimates memory requirement for queries at compilation time. This mechanism is fine for dynamic queries that need memory, but not for queries that cache the plan. With dynamic queries the plan is not reused for different set of parameters values / predicates and hence different amount of memory can be estimated based on different set of parameter values / predicates. Common memory allocating queries are that perform Sort and do Hash Match operations like Hash Join or Hash Aggregation or Hash Union. This article covers Sort with examples. It is recommended to read Plan Caching and Query Memory Part II after this article which covers Hash Match operations.   When the plan is cached by using stored procedure or other plan caching mechanisms like sp_executesql or prepared statement, SQL Server estimates memory requirement based on first set of execution parameters. Later when the same stored procedure is called with different set of parameter values, the same amount of memory is used to execute the stored procedure. This might lead to underestimation / overestimation of memory on plan reuse, overestimation of memory might not be a noticeable issue for Sort operations, but underestimation of memory will lead to spill over tempdb resulting in poor performance.   This article covers underestimation / overestimation of memory for Sort. Plan Caching and Query Memory Part II covers underestimation / overestimation for Hash Match operation. It is important to note that underestimation of memory for Sort and Hash Match operations lead to spill over tempdb and hence negatively impact performance. Overestimation of memory affects the memory needs of other concurrently executing queries. In addition, it is important to note, with Hash Match operations, overestimation of memory can actually lead to poor performance.   To read additional articles I wrote click here.   In most cases it is cheaper to pay for the compilation cost of dynamic queries than huge cost for spill over tempdb, unless memory requirement for a stored procedure does not change significantly based on predicates.   The best way to learn is to practice. To create the below tables and reproduce the behavior, join the mailing list by using this link: www.sqlworkshops.com/ml and I will send you the table creation script. Most of these concepts are also covered in our webcasts: www.sqlworkshops.com/webcasts   Enough theory, let’s see an example where we sort initially 1 month of data and then use the stored procedure to sort 6 months of data.   Let’s create a stored procedure that sorts customers by name within certain date range.   --Example provided by www.sqlworkshops.com create proc CustomersByCreationDate @CreationDateFrom datetime, @CreationDateTo datetime as begin       declare @CustomerID int, @CustomerName varchar(48), @CreationDate datetime       select @CustomerName = c.CustomerName, @CreationDate = c.CreationDate from Customers c             where c.CreationDate between @CreationDateFrom and @CreationDateTo             order by c.CustomerName       option (maxdop 1)       end go Let’s execute the stored procedure initially with 1 month date range.   set statistics time on go --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-01-31' go The stored procedure took 48 ms to complete.     The stored procedure was granted 6656 KB based on 43199.9 rows being estimated.       The estimated number of rows, 43199.9 is similar to actual number of rows 43200 and hence the memory estimation should be ok.       There was no Sort Warnings in SQL Profiler.      Now let’s execute the stored procedure with 6 month date range. --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-06-30' go The stored procedure took 679 ms to complete.      The stored procedure was granted 6656 KB based on 43199.9 rows being estimated.      The estimated number of rows, 43199.9 is way different from the actual number of rows 259200 because the estimation is based on the first set of parameter value supplied to the stored procedure which is 1 month in our case. This underestimation will lead to sort spill over tempdb, resulting in poor performance.      There was Sort Warnings in SQL Profiler.    To monitor the amount of data written and read from tempdb, one can execute select num_of_bytes_written, num_of_bytes_read from sys.dm_io_virtual_file_stats(2, NULL) before and after the stored procedure execution, for additional information refer to the webcast: www.sqlworkshops.com/webcasts.     Let’s recompile the stored procedure and then let’s first execute the stored procedure with 6 month date range.  In a production instance it is not advisable to use sp_recompile instead one should use DBCC FREEPROCCACHE (plan_handle). This is due to locking issues involved with sp_recompile, refer to our webcasts for further details.   exec sp_recompile CustomersByCreationDate go --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-06-30' go Now the stored procedure took only 294 ms instead of 679 ms.    The stored procedure was granted 26832 KB of memory.      The estimated number of rows, 259200 is similar to actual number of rows of 259200. Better performance of this stored procedure is due to better estimation of memory and avoiding sort spill over tempdb.      There was no Sort Warnings in SQL Profiler.       Now let’s execute the stored procedure with 1 month date range.   --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-01-31' go The stored procedure took 49 ms to complete, similar to our very first stored procedure execution.     This stored procedure was granted more memory (26832 KB) than necessary memory (6656 KB) based on 6 months of data estimation (259200 rows) instead of 1 month of data estimation (43199.9 rows). This is because the estimation is based on the first set of parameter value supplied to the stored procedure which is 6 months in this case. This overestimation did not affect performance, but it might affect performance of other concurrent queries requiring memory and hence overestimation is not recommended. This overestimation might affect performance Hash Match operations, refer to article Plan Caching and Query Memory Part II for further details.    Let’s recompile the stored procedure and then let’s first execute the stored procedure with 2 day date range. exec sp_recompile CustomersByCreationDate go --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-01-02' go The stored procedure took 1 ms.      The stored procedure was granted 1024 KB based on 1440 rows being estimated.      There was no Sort Warnings in SQL Profiler.      Now let’s execute the stored procedure with 6 month date range. --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-06-30' go   The stored procedure took 955 ms to complete, way higher than 679 ms or 294ms we noticed before.      The stored procedure was granted 1024 KB based on 1440 rows being estimated. But we noticed in the past this stored procedure with 6 month date range needed 26832 KB of memory to execute optimally without spill over tempdb. This is clear underestimation of memory and the reason for the very poor performance.      There was Sort Warnings in SQL Profiler. Unlike before this was a Multiple pass sort instead of Single pass sort. This occurs when granted memory is too low.      Intermediate Summary: This issue can be avoided by not caching the plan for memory allocating queries. Other possibility is to use recompile hint or optimize for hint to allocate memory for predefined date range.   Let’s recreate the stored procedure with recompile hint. --Example provided by www.sqlworkshops.com drop proc CustomersByCreationDate go create proc CustomersByCreationDate @CreationDateFrom datetime, @CreationDateTo datetime as begin       declare @CustomerID int, @CustomerName varchar(48), @CreationDate datetime       select @CustomerName = c.CustomerName, @CreationDate = c.CreationDate from Customers c             where c.CreationDate between @CreationDateFrom and @CreationDateTo             order by c.CustomerName       option (maxdop 1, recompile)       end go Let’s execute the stored procedure initially with 1 month date range and then with 6 month date range. --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-01-30' exec CustomersByCreationDate '2001-01-01', '2001-06-30' go The stored procedure took 48ms and 291 ms in line with previous optimal execution times.      The stored procedure with 1 month date range has good estimation like before.      The stored procedure with 6 month date range also has good estimation and memory grant like before because the query was recompiled with current set of parameter values.      The compilation time and compilation CPU of 1 ms is not expensive in this case compared to the performance benefit.     Let’s recreate the stored procedure with optimize for hint of 6 month date range.   --Example provided by www.sqlworkshops.com drop proc CustomersByCreationDate go create proc CustomersByCreationDate @CreationDateFrom datetime, @CreationDateTo datetime as begin       declare @CustomerID int, @CustomerName varchar(48), @CreationDate datetime       select @CustomerName = c.CustomerName, @CreationDate = c.CreationDate from Customers c             where c.CreationDate between @CreationDateFrom and @CreationDateTo             order by c.CustomerName       option (maxdop 1, optimize for (@CreationDateFrom = '2001-01-01', @CreationDateTo ='2001-06-30'))       end go Let’s execute the stored procedure initially with 1 month date range and then with 6 month date range.   --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-01-30' exec CustomersByCreationDate '2001-01-01', '2001-06-30' go The stored procedure took 48ms and 291 ms in line with previous optimal execution times.    The stored procedure with 1 month date range has overestimation of rows and memory. This is because we provided hint to optimize for 6 months of data.      The stored procedure with 6 month date range has good estimation and memory grant because we provided hint to optimize for 6 months of data.       Let’s execute the stored procedure with 12 month date range using the currently cashed plan for 6 month date range. --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-12-31' go The stored procedure took 1138 ms to complete.      2592000 rows were estimated based on optimize for hint value for 6 month date range. Actual number of rows is 524160 due to 12 month date range.      The stored procedure was granted enough memory to sort 6 month date range and not 12 month date range, so there will be spill over tempdb.      There was Sort Warnings in SQL Profiler.      As we see above, optimize for hint cannot guarantee enough memory and optimal performance compared to recompile hint.   This article covers underestimation / overestimation of memory for Sort. Plan Caching and Query Memory Part II covers underestimation / overestimation for Hash Match operation. It is important to note that underestimation of memory for Sort and Hash Match operations lead to spill over tempdb and hence negatively impact performance. Overestimation of memory affects the memory needs of other concurrently executing queries. In addition, it is important to note, with Hash Match operations, overestimation of memory can actually lead to poor performance.   Summary: Cached plan might lead to underestimation or overestimation of memory because the memory is estimated based on first set of execution parameters. It is recommended not to cache the plan if the amount of memory required to execute the stored procedure has a wide range of possibilities. One can mitigate this by using recompile hint, but that will lead to compilation overhead. However, in most cases it might be ok to pay for compilation rather than spilling sort over tempdb which could be very expensive compared to compilation cost. The other possibility is to use optimize for hint, but in case one sorts more data than hinted by optimize for hint, this will still lead to spill. On the other side there is also the possibility of overestimation leading to unnecessary memory issues for other concurrently executing queries. In case of Hash Match operations, this overestimation of memory might lead to poor performance. When the values used in optimize for hint are archived from the database, the estimation will be wrong leading to worst performance, so one has to exercise caution before using optimize for hint, recompile hint is better in this case. I explain these concepts with detailed examples in my webcasts (www.sqlworkshops.com/webcasts), I recommend you to watch them. The best way to learn is to practice. To create the above tables and reproduce the behavior, join the mailing list at www.sqlworkshops.com/ml and I will send you the relevant SQL Scripts.     Register for the upcoming 3 Day Level 400 Microsoft SQL Server 2008 and SQL Server 2005 Performance Monitoring & Tuning Hands-on Workshop in London, United Kingdom during March 15-17, 2011, click here to register / Microsoft UK TechNet.These are hands-on workshops with a maximum of 12 participants and not lectures. For consulting engagements click here.     Disclaimer and copyright information:This article refers to organizations and products that may be the trademarks or registered trademarks of their various owners. Copyright of this article belongs to R Meyyappan / www.sqlworkshops.com. You may freely use the ideas and concepts discussed in this article with acknowledgement (www.sqlworkshops.com), but you may not claim any of it as your own work. This article is for informational purposes only; you use any of the suggestions given here entirely at your own risk.   R Meyyappan [email protected] LinkedIn: http://at.linkedin.com/in/rmeyyappan

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  • How to find data usage of a user on my website?

    - by Dharmik
    I have a website (project) where users get logged in, do their work and then they log out. I need to build a report that displays how much each person has used of data. (bandwidth, how much was downloaded in Kb, etc) So the process may be like counting start of usage from user login to user logout. I have seen a little about Webalizer and AWStats for something like this, But I am not sure how they work. I have tried Content-Length but some pages don't send content-length.I have also seen mod_bandwidth but still I am little confused. This process is needed for my site because now, our company is thinking of charging per usage and also bandwidth allocation for each users (according to their membership). I haven't worked with this type of tools, I am newbie in this matter. I have done only simple websites not any setting like this in Apache or Linux. My project is in Codeigniter.

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  • Max ram for computer 16GB or 8GB

    - by Laptop memory question
    Manufacturer's specifications for my notebook say memory can be extended from 4GB to 8GB. Whereas, running sudo dmidecode suggests the computer can use 16GB as below: Handle 0x0037, DMI type 16, 15 bytes Physical Memory Array Location: System Board Or Motherboard Use: System Memory Error Correction Type: None Maximum Capacity: 16 GB Error Information Handle: Not Provided Number Of Devices: 4 Which one is correct?

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  • Why do we use to talk about addresses and memory of variable in C?

    - by user2720323
    Why do we use to talk about addresses and memory of variable in C, where in other languages (like in Java, .Net etc) we do not talk about variable address and memory in a program, we will directly use the variables. But in C Language we are listening the word address and memory. How to explain this? I hope C is high level language designed over the assembly language. So C is a thin layer over assembly language (in assembly language we will use memory locations to store a variable and track a variable). But in other languages these addresses and memory related things are wrapped in that specific language, so that we will not listen these words.

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  • Apache heavy load VIRT vs RES memory

    - by pako
    I have a Debian 5 server, which gets a lot of traffic. Right now the server has 4 GB of RAM and no swap memory. I see in top that Apache processes consume roughly 180 MB virtual memory (VIRT) each, and 16 MB of real RAM (RES). So how many Apache threads can I have running at the same time? About 4 GB / 180 MB = 22 or 4 GB / 16 MB = 256?

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