Re: tuning of Atlas on x86/NUMA

> Mikhail,
>
> ATLAS presently does almost not SMP-related empirical tuning.  We are
> presently looking at it, but the present package does none.  Here's a link
> you may be interested in from the errata:
>   http://math-atlas.sourceforge.net/errata.html#SMPCE
>
>>How the atlas tuning process (for example, for dgemm kernel) is
>>organized for the case
>>of SMP/NUMA servers w/CPUs having shared cache ? For example, for
>>dual-socket quad-core Opteron server ?
>>
>>If dgemm tuning takes into account shared cache size, and is tuned
>>>only "single threaded" (sequential run),
>>then it'll propose that it can use whole cache (for example, 2 MB L3
>>for Opteron 2350). But for multithreaded dgemm w/4 threads per CPU
>>only 512K of L3 will be available w/o a lot of cache miss. Therefore
>>multithreaded version requires, IMHO, "independed" (from sequential
>>version) tuning.
>
>>And the second question is about using of process affinity (taskset
>>for Linux) and NUMA-allocation of memory
>>(using of numactl) at the tuning process. Does it takes into account
>>this possibilities or there is no serious reasons
>>to use taskset/numactl in tuning ?
>
> We are presently looking at the affects of using processor affinity.  I have
> no idea what numactl is, do you have a link?
>
> Cheers,
> Clint
>
> **************************************************************************
> ** R. Clint Whaley, PhD ** Assist Prof, UTSA ** www.cs.utsa.edu/~whaley **
> **************************************************************************
>
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