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NUMA Aware Software?
- Thread starter mikeblas
- Start date
paulmofyourhand
[H]ard|Gawd
- Joined
- Mar 26, 2002
- Messages
- 1,331
microsoft server 2k3
paulmofyourhand said:microsoft server 2k3
Kind of. The OS knows enough about NUMA to tell applications that ask about it.
Do you know for a fact that it gives processor affinity to threads so that the memory those threads are working on are reachable as cheaply as possible by the code doing the work?
With the Opteron-based solutions being so popular, I'm surprised this question isn't a FAQ.
olaf2821 said:So is XP Pro SP2
How does it work? It doesn't expose any of the NUMA APIs (like GetNumaAvailableMemoryNode or GetNumaNodeProcessorMask). Even if it was NUMA-capable, a program that ran on it wouldn't be able to sniff out its environment well enough to run efficiently.
mikeblas said:How does it work? It doesn't expose any of the NUMA APIs (like GetNumaAvailableMemoryNode or GetNumaNodeProcessorMask). Even if it was NUMA-capable, a program that ran on it wouldn't be able to sniff out its environment well enough to run efficiently.
Beats the hell out of me dude, all I know is that I have seen XP SP2 listed as having NUMA support dozens of times, and doing a quick google search seems to back that up. It's very possible it isn't as fast or efficient as 2K3's is, but that's a question for someone more versed in this than myself My understanding was SP2 still had access to loads of memory bandwidth and programs didn't need to be coded for it to take advantage of it.
olaf2821 said:My understanding was SP2 still had access to loads of memory bandwidth and programs didn't need to be coded for it to take advantage of it.
There is no doubt that programs need to be coded carefully to take advantage of NUMA. The NUMA Support article in MSDN has a pretty concise explanation.
Turns out that MSDN is wrong about the APIs being available only on Windows 2003 and higher; they are indeed on XP. (On SP 2, at least; that's all I have to test.)
The plot thickens! I asked around at work, and it turns out the APIs are present in Windows XP but are not supported. They're not supported because there's a chance they don't work; the code was changed for Windows Server 2003.
MSDN is correct about NUMA not being supported in Windows XP.
MSDN is correct about NUMA not being supported in Windows XP.