Can multiple processes on a Windows 2000 server use more than 4GB without PAE?

R

Rui Vilao

Greetings,

We have a 8 CPU box with 8GB RAM running Windows 2000 datacenter.
This system does not host applications that need large amounts of memory, but it
does host a lot of applications that don't support AWE...

I am a bit confused with the 4GB addressing limit of windows 2000...
Is this a per process limit or is it a limit for the whole system?

My understanding is that by default, the Virtual Address Space size per user
is 4 GB of RAM (2GB for user address space + 2 GB system address space).
This means that many running processes that don't make usage of large amount of
memory can eventually make usage, all together, of the whole physical memory
(8GB) which is more than 4GB...
Otherwise it would be of no use buying more than 4GB memory for a Windows 2000
server if the running applications don't support AWE...

Any help/clarification is highly appreciated.

Thanks in advance for your help,

Kind Regards,

Rui Vilao.
 
K

Kevin [MSFT]

Hello,

Applications that do not support AWE can still take advantage of the greater than 4GB of RAM on a server. Each process can allocate 2GB of "virtual address space" for it's use in user mode
(do not use the /3GB switch with the /PAE switch unless you absolutely have to). 2GB for kernel is system wide, so there is only one 2GB kernel space. The application does not know or care if
the address space it's using is currently in physical RAM or paged out. Obviously, if it's address space is in physical RAM, it's going to have much better performance than if it were being paged.

So on your system, having 8GB of RAM, more applications would be able to run and have more "physical memory" allocated for it's use. If you only had 4GB of RAM, then once that 4GB of
physical RAM was used up, the OS would have to start paging memory to handle more applications. So, basically speaking, the more RAM you have on a box, the more physical memory that
can be used by the apps on the system.

Applications that are designed to utilize the AWE API's are able to allocate large chunks of physical RAM that can only be used for it's process and nothing else.

I hope this helps!

This message is provided as is and does not imply any warranty or gaurantee of support of any kind.

--------------------
| From: (e-mail address removed) (Rui Vilao)
| Newsgroups: microsoft.public.win2000.advanced_server
| Subject: Can multiple processes on a Windows 2000 server use more than 4GB without PAE?
| Date: 11 Jan 2004 18:30:06 -0800
| Organization: http://groups.google.com
| Lines: 24
| Message-ID: <[email protected]>
| NNTP-Posting-Host: 194.65.14.75
| Content-Type: text/plain; charset=ISO-8859-1
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| X-Trace: posting.google.com 1073874607 16117 127.0.0.1 (12 Jan 2004 02:30:07 GMT)
| X-Complaints-To: (e-mail address removed)
| NNTP-Posting-Date: Mon, 12 Jan 2004 02:30:07 +0000 (UTC)
| Path: cpmsftngxa07.phx.gbl!cpmsftngxa10.phx.gbl!cpmsftngxa06.phx.gbl!TK2MSFTNGP08.phx.gbl!newsfeed00.sul.t-online.de!t-online.de!newsfeed.icl.net!newsfeed.fjserv.net!
news.maxwell.syr.edu!postnews1.google.com!postnews2.google.com!not-for-mail
| Xref: cpmsftngxa07.phx.gbl microsoft.public.win2000.advanced_server:15803
| X-Tomcat-NG: microsoft.public.win2000.advanced_server
|
| Greetings,
|
| We have a 8 CPU box with 8GB RAM running Windows 2000 datacenter.
| This system does not host applications that need large amounts of memory, but it
| does host a lot of applications that don't support AWE...
|
| I am a bit confused with the 4GB addressing limit of windows 2000...
| Is this a per process limit or is it a limit for the whole system?
|
| My understanding is that by default, the Virtual Address Space size per user
| is 4 GB of RAM (2GB for user address space + 2 GB system address space).
| This means that many running processes that don't make usage of large amount of
| memory can eventually make usage, all together, of the whole physical memory
| (8GB) which is more than 4GB...
| Otherwise it would be of no use buying more than 4GB memory for a Windows 2000
| server if the running applications don't support AWE...
|
| Any help/clarification is highly appreciated.
|
| Thanks in advance for your help,
|
| Kind Regards,
|
| Rui Vilao.
|
 
R

Rui Vilao

Hi,

Sorry for the multiple posts 8got some http errors, so I retied…)
Many thanks to Kevin, for his contribution.
That was more or less was I was thinking.

What about the size of the kernel and process memory if I have a server with 3GB?
Will it be 50%-50% i.e. 1.5GB for the kernel memory and 1.5Gb for the user process?

TIA.

Kind Regards,

Rui Vilao
 
K

Kevin [MSFT]

You're welcome!

As far as applications and even the kernel are concerned, they have a "virtual address space" that they can use - by default, 2GB for user and 2 for kernel. They don't care or know if you actually
have 4GB of physical RAM or only 3GB (now obviously, the kernel is always going to have some things that cannot be paged out. The memory space we use for this is referred to as NPP or Non-
Page Pool - if you run out of NPP, the system will not be able to continue).

Once physical RAM is used up, we have to start paging to free up memory. Just remember that applications always think that they have their own 2GB of address space no matter how much
RAM is actually on the box.

This message is provided as is and does not imply any warranty or gaurantee of support of any kind.

--------------------
| From: (e-mail address removed) (Rui Vilao)
| Newsgroups: microsoft.public.win2000.advanced_server
| Subject: Re: Can multiple processes on a Windows 2000 server use more than 4GB without PAE?
| Date: 13 Jan 2004 00:12:38 -0800
| Organization: http://groups.google.com
| Lines: 14
| Message-ID: <[email protected]>
| References: <[email protected]> <XUQ#[email protected]>
| NNTP-Posting-Host: 194.65.14.75
| Content-Type: text/plain; charset=ISO-8859-1
| Content-Transfer-Encoding: 8bit
| X-Trace: posting.google.com 1073981558 32670 127.0.0.1 (13 Jan 2004 08:12:38 GMT)
| X-Complaints-To: (e-mail address removed)
| NNTP-Posting-Date: Tue, 13 Jan 2004 08:12:38 +0000 (UTC)
| Path: cpmsftngxa07.phx.gbl!cpmsftngxa10.phx.gbl!TK2MSFTNGXA06.phx.gbl!cpmsftngxa06.phx.gbl!TK2MSFTNGP08.phx.gbl!newsfeed00.sul.t-online.de!t-online.de!diablo.theplanet.net!
news.maxwell.syr.edu!postnews2.google.com!not-for-mail
| Xref: cpmsftngxa07.phx.gbl microsoft.public.win2000.advanced_server:15863
| X-Tomcat-NG: microsoft.public.win2000.advanced_server
|
| Hi,
|
| Sorry for the multiple posts 8got some http errors, so I retied…)
| Many thanks to Kevin, for his contribution.
| That was more or less was I was thinking.
|
| What about the size of the kernel and process memory if I have a server with 3GB?
| Will it be 50%-50% i.e. 1.5GB for the kernel memory and 1.5Gb for the user process?
|
| TIA.
|
| Kind Regards,
|
| Rui Vilao
|
 

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