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Topic Title: Win XP SP2 and NUMA
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Created On: 10/21/2004 04:15 PM
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 10/21/2004 04:15 PM
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jklincewicz
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I enabled ACPI 2.0 on my BIOS (Tiger Tyan K8W) and put the /PAE switch in my boot.ini file, but Sisoft Sandra keeps telling me NUMA is not detected (either the BIOS or OS support.)

I have 4 512MB Corsair Twinx sticks populating all dimm slots. Any thoughts ??

TIA

Jan
 10/21/2004 05:23 PM
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redclawkefar
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do you have dual cpu's or just a single? no NUMA available in single cpu setup... which TYAN mobo... s2875 or S2875S?

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SYSTEM-1: 2x Viewsonic VX900-2 19"| Tyan S2885ANRF (Rev.A, bios v2.07) | 1x ATI Radeon X800 Pro 256MB | 2x AMD Opteron 248-HE Single-Core CPU | 8x 512mb PC3200 Corsair XMS Series ECC Reg. (CMX512RE-3200LL) | 2x Seagate LVD 36.7Gb U320 SCSI 10,000rpm RAID0 (ST336607LW) | 1x Seagate LVD 36.7Gb U320 SCSI 1
 10/21/2004 05:25 PM
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jklincewicz
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QUOTE (redclawkefar @ Oct 21 2004, 01:23 PM) do you have dual cpu's or just a single?  no NUMA available in single cpu setup... which TYAN mobo... s2875 or S2875S?
A Dualie of course !!! The S2875 .....
 10/21/2004 06:40 PM
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redclawkefar
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so when you hit the windows key + pause/break key together, it says "physical address extension" right?

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SYSTEM-1: 2x Viewsonic VX900-2 19"| Tyan S2885ANRF (Rev.A, bios v2.07) | 1x ATI Radeon X800 Pro 256MB | 2x AMD Opteron 248-HE Single-Core CPU | 8x 512mb PC3200 Corsair XMS Series ECC Reg. (CMX512RE-3200LL) | 2x Seagate LVD 36.7Gb U320 SCSI 10,000rpm RAID0 (ST336607LW) | 1x Seagate LVD 36.7Gb U320 SCSI 1
 10/21/2004 11:42 PM
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OrangesAway
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(Edit PAE (Physical Address Extension) and NUMA are two different things... Since your system has 2 GB, no need for PAE

Unfortunately, the S2875 should not support NUMA, there is only one set of memory slots connected to Processor 0.



Whereas the S2885 has memory slots for both processors.



See the Tyan FAQ for the Tyan S2885' ">http://www.tyan.com/support/html/f_s2885.html (not the board you have)

QUOTE How is memory presented to the processor?

Each processor can have physical memory connected to it.  After initialization, the memory map for the system presents all physical memory as a single contiguous extent.  This extent is formed in one of two ways.  The first way is through the concatenation of all processor memory, also known as NUMA (Non-Uniform Memory Architecture).  For example, all of processor 0's memory, followed by all of processor 1's memory and etc.  The second way is by the interleaving by page of all processor memory.  For example, a page from processor 0's memory, followed by a page from processor 1's memory and etc.  The interleaved mechanism (option #2) has better overall uniformity of latency but the concatenation mechanism (option #1) is more usable for an operating system capable of implementing memory affinity management.  After initialization, all memory appears equal to the casual programmer.  No special addressing mechanisms are necessary to access physical memory attached to a processor other than the processor executing the memory reference instruction.
 
Is it necessary for the OS to have specific memory management considerations; given the NUMA approach used by AMD Opteron system?

Although not necessary, operating systems that provide careful memory and scheduling affinity improve overall memory latency and bandwidth and reduce traffic on the system's buses, which can have important performance improvement in some applications.  Both Windows Extended 64 bit and x86-64 Linux have some NUMA support for memory affinity and thread-biasing to enable optimal application performance considerations.  Processes and threads that use local data are advised to allocate that local data space from within the thread or process that uses that data the most, to enable maximum benefit from the OS NUMA support.


If all the memory is associated with one processor, as it is in the S2875, there is little benefit to define processor/memory affinity
 10/22/2004 07:39 AM
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jklincewicz
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Thanks - I had seen those before, but never really looked hard enough to see that all the memory was assigned to one processor !! Obviously, that about wraps it up for NUMA !! It seems the Tyan Thunder (with more DIMM slots) supports it, but I really wanted to stick to a standard ATX ..

Maybe when the dual cores ship I'll look at a new MOBO and case. Many thanks !!

I guess I may as well take those /pae entries out of my boot.ini ??
 10/23/2004 12:18 AM
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OrangesAway
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QUOTE (OrangesAway @ Oct 21 2004, 07:42 PM)
...Since your system has 2 GB, no need for PAE

Just to correct myself, there are cases where Windows XP SP2 uses PAE even if there is less than 4 GB of memory, if Data Execution Protection (DEP) is enabled.

See KB 875352 - A detailed description of the Data Execution Prevention (DEP) feature in Windows XP Service Pack 2' ">http://support.microsoft.com/default.aspx?kbid=875352 or Changes to Functionality in Microsoft Windows XP Service Pack 2' ">http://www.microsoft.com/techn...maintain/sp2mempr.mspx

As I read it, enabling DEP, automatically enables PAE, so not sure you need to add it (am away from my other machine so can't test it and the MS docs don't say).

However, if DEP is disabled, you can (although I don't know any other reason to) enable PAE.
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