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From: "Brett E." <>
To: Andrew Theurer <>
Cc: Andi Kleen <>, "Bryan O'Sullivan" <>,
	"Martin J. Bligh" <>,
Subject: Re: How can I optimize a process on a NUMA architecture(x86-64 specifically)?
Date: Mon, 24 May 2004 18:09:12 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Andrew Theurer wrote:

> On Sunday 23 May 2004 09:28, Andi Kleen wrote:
>>On Sat, May 22, 2004 at 05:28:09PM -0700, Bryan O'Sullivan wrote:
>>>On Fri, 2004-05-21 at 16:42, Brett E. wrote:
>>>>Right now, 5 processes are running taking up a good deal of the CPU
>>>>doing memory-intensive work(cacheing) and I notice that none of the
>>>>processes seem to have CPU affinity.
>>>I don't know what kind of system you're running on, but if it's a
>>>multi-CPU Opteron, it is normally a sufficient fudge to just use
>>>sched_setaffinity to bind individual processes to specific CPUs.  The
>>>mainline kernel memory allocator does the right thing in that case, and
>>>allocates memory locally when it can.
>>>You can use the taskset command to get at this from the command line, so
>>>you may not even need to modify your code.
>>Linus also merged the NUMA API support into mainline now with 2.6.7rc1, so
>>you can use numactl for more finegrained tuning.
> FYI Brett, some Opteron systems have a BIOS option to interleave memory.  If 
> you are going to make use of NUMA, I think you want to not interleave.
Thanks for the heads up, I just disabled interleaving in the BIOS.

> Also, if you have a 25% imbalance within a domain/node, the scheduler can have 
> a tendency to bounce around a task for fairness.  That might be why you are 
> seeing little/no affinity to a cpu (even top might be causing some of this).   
> Not sure what the threshold is between domains/nodes, but I am curious if it 
> still happens with CONFIG_NUMA on.  If these are long lived cpu bound 
> processes, I would try to have the number of processes be a multiple of the 
> number of cpus.
I have CONFIG_NUMA on and yes these are long-lived processes(duration is 
1 hour).  And you and I are on the same wavelength, I'm imagining 3 
processes per CPU with apache handing off work to the processes in 
question.  This is on a 1.6ghz 2-way opteron if that matters at all. 
Hopefully I can make the modifications and test this tomorrow.



  parent reply	other threads:[~2004-05-25  1:10 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
     [not found] ` <>
     [not found]   ` <>
     [not found]     ` <>
2004-05-21 19:17       ` How can I optimize a process on a NUMA architecture(x86-64 specifically)? Andi Kleen
     [not found]       ` <>
     [not found]         ` <>
2004-05-21 19:19           ` Andi Kleen
2004-05-21 20:32             ` Martin J. Bligh
2004-05-21 23:42               ` Brett E.
2004-05-22  6:13                 ` Martin J. Bligh
2004-05-22  7:41                   ` Andi Kleen
2004-05-23  0:28                 ` Bryan O'Sullivan
2004-05-23 14:28                   ` Andi Kleen
2004-05-24 22:00                     ` Andrew Theurer
2004-05-25  0:27                       ` Scott Robert Ladd
2004-05-25  1:09                       ` Brett E. [this message]
     [not found]     ` <>
2004-05-23 11:57       ` Andi Kleen
2004-05-21  0:51 Brett E.
2004-05-21  1:29 ` Jesse Barnes
2004-05-21  6:37 ` Martin J. Bligh
2004-05-21 17:27   ` Brett E.
2004-05-21 17:46     ` Martin J. Bligh
2004-05-21 18:14       ` Brett E.
2004-05-21 18:30         ` Martin J. Bligh
2004-05-21 18:58         ` Jesse Barnes
2004-05-21 19:08           ` Martin J. Bligh
2004-05-23  2:49     ` David Schwartz

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