Large system cache settings

[Kpark]

I have been looking to optimize settings on some of our Windows servers.
These servers all have 4GB of RAM installed (about 3.3GB available because we
are not using /PAE). Since we seem to have plenty of RAM, I want to maximize
the virtual address space available to be used by the cache manager. I
marked the option to adjust memory for best performance of the system cache,
rebooted, and verified the registry key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory
Management\LargeSystemCache is now set to 1. When I try to verify the cache
virtual size in Windbg, it seems to still be set to 512MB rather than the
960MB maximum size.
Windbg output:
lkd> dd mmsizeofsystemcacheinpages l 1
808b4100 00020000

Why can't I get a larger cache virtual size? The only possibility I can
come up with is some other registry setting preventing a larger cache, but I
can't find anything.

Contents of HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session
Manager\Memory Management:

"ClearPageFileAtShutdown"=dword:00000000
"DisablePagingExecutive"=dword:00000000
"LargeSystemCache"=dword:00000001
"NonPagedPoolQuota"=dword:00000000
"NonPagedPoolSize"=dword:00000000
"PagedPoolQuota"=dword:00000000
"PagedPoolSize"=dword:00000000
"SecondLevelDataCache"=dword:00000000
"SystemPages"=dword:000c3000
"PagingFiles"=hex(7):63,00,3a,00,5c,00,70,00,61,00,67,00,65,00,66,00,69,00,6c,\
00,65,00,2e,00,73,00,79,00,73,00,20,00,31,00,30,00,36,00,30,00,20,00,31,00,\
30,00,36,00,30,00,00,00,65,00,3a,00,5c,00,70,00,61,00,67,00,65,00,66,00,69,\
00,6c,00,65,00,2e,00,73,00,79,00,73,00,20,00,33,00,35,00,30,00,30,00,20,00,\
33,00,35,00,30,00,30,00,00,00,00,00
"PhysicalAddressExtension"=dword:00000000
"WriteWatch"=dword:00000001

Any help greatly appreciated.

 

[Kpark]

This appears to be a semi-documented feature of what features your server has
installed. My servers all have Terminal Services installed. With TS
installed, it appears the registry settings are ignored. You can change them
to your hearts content, but they are ignored and you can only have 512MB of
virtual address space for the system file cache. In my testing, it appears
that domain controllers exhibit the same behavior as well.

"Kpark" wrote:

> I have been looking to optimize settings on some of our Windows servers.
> These servers all have 4GB of RAM installed (about 3.3GB available because we
> are not using /PAE). Since we seem to have plenty of RAM, I want to maximize
> the virtual address space available to be used by the cache manager. I
> marked the option to adjust memory for best performance of the system cache,
> rebooted, and verified the registry key
> HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory
> Management\LargeSystemCache is now set to 1. When I try to verify the cache
> virtual size in Windbg, it seems to still be set to 512MB rather than the
> 960MB maximum size.
> Windbg output:
> lkd> dd mmsizeofsystemcacheinpages l 1
> 808b4100 00020000
>
> Why can't I get a larger cache virtual size? The only possibility I can
> come up with is some other registry setting preventing a larger cache, but I
> can't find anything.
>
> Contents of HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session
> Manager\Memory Management:
>
> "ClearPageFileAtShutdown"=dword:00000000
> "DisablePagingExecutive"=dword:00000000
> "LargeSystemCache"=dword:00000001
> "NonPagedPoolQuota"=dword:00000000
> "NonPagedPoolSize"=dword:00000000
> "PagedPoolQuota"=dword:00000000
> "PagedPoolSize"=dword:00000000
> "SecondLevelDataCache"=dword:00000000
> "SystemPages"=dword:000c3000
> "PagingFiles"=hex(7):63,00,3a,00,5c,00,70,00,61,00,67,00,65,00,66,00,69,00,6c,\
> 00,65,00,2e,00,73,00,79,00,73,00,20,00,31,00,30,00,36,00,30,00,20,00,31,00,\
> 30,00,36,00,30,00,00,00,65,00,3a,00,5c,00,70,00,61,00,67,00,65,00,66,00,69,\
> 00,6c,00,65,00,2e,00,73,00,79,00,73,00,20,00,33,00,35,00,30,00,30,00,20,00,\
> 33,00,35,00,30,00,30,00,00,00,00,00
> "PhysicalAddressExtension"=dword:00000000
> "WriteWatch"=dword:00000001
>
> Any help greatly appreciated.
>