Why is my non-paged pool so small?

NTDEV
1

Question: Why does Windows 2000 sometimes allocate less than the maximum
sized non-paged pool on systems with plenty of physical memory (2-3GB)?

Various Microsoft sources tell me the size of non-paged pool has a
hard-coded limit of around 249MB. I have seen various number but they
are all around that value. Further, the default algorithm for
calculating the size of non-paged pool maxes out around 1.2GB of
physical memory (~20% * sizeof physical memory). On most machines, when
I check the value of MmMaximumNonPagedPoolInBytes it will be around the
maximum value as stated by Microsoft. However, we occasionally come
across a machine where the size of non-paged pool is not at the maximum.
For instance, right now we have two 2000 server machines. Both have 2GB
of memory but different motherboards. MmMaximumNonPagedPoolInBytes is
0x08c00000 (140MB). We had a third machine that, in the past, exhibited
the problem. We reinstalled the OS, a drastic action, and that fixed the
problem. Therefore, we don’t believe this is a hardware issue.

We’ve tried playing with the registry value “NonPagedPoolSize” in
HKLM\System\CurrentControlSet\Control\Session Manager\Memory Management
(0, 0xffffffff, 0x08000000, 0x80) and have yet to see any effect.
MmMaximumNonPagedPoolInBytes stayed at 0x08c00000.

Does anyone out there know what could be causing this problem?

Thanks,
Aaron Stavens
NetMotion Wireless, Inc.

2

You don’t by any chance have /3GB set on those machines that have lower
limits despite having a large memory amount?

–
Mats

-----Original Message-----
From: Aaron Stavens [mailto:xxxxx@nmwco.com]
Sent: Saturday, March 20, 2004 12:35 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] Why is my non-paged pool so small?

Question: Why does Windows 2000 sometimes allocate less than
the maximum
sized non-paged pool on systems with plenty of physical
memory (2-3GB)?

Various Microsoft sources tell me the size of non-paged pool has a
hard-coded limit of around 249MB. I have seen various number but they
are all around that value. Further, the default algorithm for
calculating the size of non-paged pool maxes out around 1.2GB of
physical memory (~20% * sizeof physical memory). On most
machines, when
I check the value of MmMaximumNonPagedPoolInBytes it will be
around the
maximum value as stated by Microsoft. However, we occasionally come
across a machine where the size of non-paged pool is not at
the maximum.
For instance, right now we have two 2000 server machines.
Both have 2GB
of memory but different motherboards. MmMaximumNonPagedPoolInBytes is
0x08c00000 (140MB). We had a third machine that, in the past,
exhibited
the problem. We reinstalled the OS, a drastic action, and
that fixed the
problem. Therefore, we don’t believe this is a hardware issue.

We’ve tried playing with the registry value “NonPagedPoolSize” in
HKLM\System\CurrentControlSet\Control\Session Manager\Memory
Management
(0, 0xffffffff, 0x08000000, 0x80) and have yet to see any effect.
MmMaximumNonPagedPoolInBytes stayed at 0x08c00000.

Does anyone out there know what could be causing this problem?

Thanks,
Aaron Stavens
NetMotion Wireless, Inc.

Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

You are currently subscribed to ntdev as: xxxxx@3dlabs.com
To unsubscribe send a blank email to xxxxx@lists.osr.com

3

Thanks for the suggestion, but no. I just checked. Any other thoughts?

Aaron Stavens
NetMotion Wireless, Inc.

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of
xxxxx@3Dlabs.com
Sent: Monday, March 22, 2004 5:30 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] Why is my non-paged pool so small?

You don’t by any chance have /3GB set on those machines that have lower
limits despite having a large memory amount?

–
Mats

-----Original Message-----
From: Aaron Stavens [mailto:xxxxx@nmwco.com]
Sent: Saturday, March 20, 2004 12:35 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] Why is my non-paged pool so small?

Question: Why does Windows 2000 sometimes allocate less than
the maximum
sized non-paged pool on systems with plenty of physical
memory (2-3GB)?

4

No suggestions, but in the list tradition, I’ll ask what you’re actually
trying to achieve…

It’s sometimes not always that the obvious question isn’t what you should be
asking, and to look at something from another perspective can sometimes help
solve the problem.

Do you REALLY have to have everything in the nonpaged pool [Yes, I know,
some things have to be in non-paged pool], or can some data be stored in
pageable memory.

–
Mats

-----Original Message-----
From: Aaron Stavens [mailto:xxxxx@nmwco.com]
Sent: Monday, March 22, 2004 5:14 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] Why is my non-paged pool so small?

Thanks for the suggestion, but no. I just checked. Any other thoughts?

Aaron Stavens
NetMotion Wireless, Inc.

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of
xxxxx@3Dlabs.com
Sent: Monday, March 22, 2004 5:30 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] Why is my non-paged pool so small?

You don’t by any chance have /3GB set on those machines that
have lower
limits despite having a large memory amount?

–
Mats

> -----Original Message-----
> From: Aaron Stavens [mailto:xxxxx@nmwco.com]
> Sent: Saturday, March 20, 2004 12:35 AM
> To: Windows System Software Devs Interest List
> Subject: [ntdev] Why is my non-paged pool so small?
>
>
> Question: Why does Windows 2000 sometimes allocate less than
> the maximum
> sized non-paged pool on systems with plenty of physical
> memory (2-3GB)?

Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

You are currently subscribed to ntdev as: xxxxx@3dlabs.com
To unsubscribe send a blank email to xxxxx@lists.osr.com

5

Actually, no we don’t have to have everything in non-paged pool. Really,
most of it doesn’t even have to be in kernel mode. A long time ago, the
decision was made to make one of the components a kernel mode
application. Further, the code is called at dispatch level a lot
(network activity) and makes heavy use of spin locks to synchronize
access to its data structures. That is how this release of the product
is structured. So, in that sense, we must use non-paged pool. As a
result, we are trying to track down the memory sizing issue we are
seeing in our lab. We want to have a solution should a customer run into
the problem.

Having a kernel mode application *is* causing the engineers pain and we
are lobbying to move that component up user mode, but that won’t help
already deployed product.

Aaron

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of
xxxxx@3Dlabs.com
Sent: Monday, March 22, 2004 9:24 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] Why is my non-paged pool so small?

No suggestions, but in the list tradition, I’ll ask what you’re actually
trying to achieve…

It’s sometimes not always that the obvious question isn’t what you
should be
asking, and to look at something from another perspective can sometimes
help
solve the problem.

Do you REALLY have to have everything in the nonpaged pool [Yes, I know,
some things have to be in non-paged pool], or can some data be stored in
pageable memory.

–
Mats

-----Original Message-----
From: Aaron Stavens [mailto:xxxxx@nmwco.com]
Sent: Monday, March 22, 2004 5:14 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] Why is my non-paged pool so small?

Thanks for the suggestion, but no. I just checked. Any other thoughts?

Aaron Stavens
NetMotion Wireless, Inc.

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of
xxxxx@3Dlabs.com
Sent: Monday, March 22, 2004 5:30 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] Why is my non-paged pool so small?

You don’t by any chance have /3GB set on those machines that
have lower
limits despite having a large memory amount?

–
Mats

> -----Original Message-----
> From: Aaron Stavens [mailto:xxxxx@nmwco.com]
> Sent: Saturday, March 20, 2004 12:35 AM
> To: Windows System Software Devs Interest List
> Subject: [ntdev] Why is my non-paged pool so small?
>
>
> Question: Why does Windows 2000 sometimes allocate less than
> the maximum
> sized non-paged pool on systems with plenty of physical
> memory (2-3GB)?

Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

You are currently subscribed to ntdev as: xxxxx@3dlabs.com
To unsubscribe send a blank email to xxxxx@lists.osr.com

Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

You are currently subscribed to ntdev as: xxxxx@nmwco.com
To unsubscribe send a blank email to xxxxx@lists.osr.com