2

I have two Windows Server 2008 R2 machines with the same spec (24G RAM). However, the Kernel memory is quite different: machine 1 has 206M of paged kernel memory and 168M nonpaged. Machine 2 has 998M paged and 825M nonpaged. I got these numbers from Windows Task Manager.

From what I know the Kernel memory is calculated and optimized based on the spec of the machine. But why is there a significant differences between the two machines with the same spec? Also, is there a way to set the Kernel memory?

Any help or suggestion is appreciated.

Brian
  • 21
  • 2
  • 1
    why do you think that the higher values are better? Check with poolmon, which pool tag is more used on the other system: http://superuser.com/a/674725/174557 – magicandre1981 Mar 31 '15 at 04:32
  • I'm doing load testing on the machine and I need to increase the number of maximum concurrent TCP connections. After trying many different solutions and still don't work, one suggestion is to increase the NonPaged Kernel Memory. When running the same load test, machine 2 can open more TCP connections than machine 1, so I suspect there is correlation between. Also, I use poolmon and I don't see a memory leak on either machine. – Brian Mar 31 '15 at 20:54
  • compare the poolmon outputs on both systems. Which pool tag is has a higher usage on that 1 system with a higher kernel usage? – magicandre1981 Apr 01 '15 at 04:35
  • Ntfx and File. Actually, do you know which pool tag is used by TCP connections? not sure if this question makes sense...but what I need is to increase the NonPaged Kernel Memory used by TCP connections so I can potentially go over the current limit. – Brian Apr 01 '15 at 23:59
  • both are NTFS/File operation related. So on server you have more DISK/FILE IO compared to the other. This is unrelated to TCP. – magicandre1981 Apr 02 '15 at 04:29

1 Answers1

1

This TechNet article about adjusting managed memory limits for Windows 2000 discusses the subkey HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Memory Management

I've spotted the node in Windows 8.1, so I assume it and the relevant items were also present in Windows NT 6.1, along with other keys: Memory Management

The two limits you're asking about can be given values in bytes, in PagedPoolSize and NonPagedPoolSize.

Giving NonPagedPoolSize a value will create a pool of that size, change it back to 0 to have Windows optimize it dynamically.

It is strongly suggested you read the documentation (or request a summary explaination) for PagedPoolSize; the effect of a value changes across thresholds.

Please note the warning about not changing the L2 key.

I recommend not changing any of these values until researching them further and having an easy restore process readily available.

Louis Waweru
  • 23,945
  • 39
  • 132
  • 198
  • I changed the NonPagedPoolSize to 0x20000000 (512MB) and restart the machine. However, Windows Task Manager is showing 102MB Nonpaged Kernel Memory, which is less than before... – Brian Mar 31 '15 at 20:49
  • Hi @Brian, I was playing around with these in a VM and I didn't notice an effect either. I did notice that the limits were [extremely high](http://i.imgur.com/3Kym6a7.png) and that Windows would grow the pools beyond physical RAM if needed... – Louis Waweru Apr 01 '15 at 00:17
  • Hm interesting. I still have no luck increasing the pool size. And I don't understand why the computed optimized values are so different for two machines with the same spec. – Brian Apr 02 '15 at 00:01
  • Hi @Brian, I only happened on that article discussing an unsupported OS, so I can't help control these settings it seems. The topics and how your goal relates are interesting to me, though! So, I'd like to help in so far as I can. Would you please update your question with the following: 1) things you've tried, but not just regarding the memory pool (what did you try/observe in your load tests?); 2) What sort of problem are you dealing with? Is it that the servers choose to give up on users instead of growing the pool? Are you just curious to make observations for pool sizes you choose? – Louis Waweru Apr 02 '15 at 04:00