[Beowulf] [External] Re: AMD and AVX512

[Prentice Bisbal]

i also think you're hpl numbers on the amd chip are low, you should be

   > 4000 which would put you closer to intel, but intel will still edge

out just because it has a higher base clock.

I think I could probably get better numbers out of the AMD chip now, 
too. I've done some testing since then compiler and library choice can 
make a noticeable difference for the AMD processors. Unfortunately, I no 
longer have access to that 7H12 system to test again.


Prentice

On 6/16/21 1:53 PM, Michael Di Domenico wrote:
> AMD's argument is a little unsalesmen like, but i'd buy it as an
> explanation.  avx512 uptake isn't a profound as intel would lead you
> to believe and the push to GPU's for vectors will probably remove the
> need for most of these high end vectors sooner or later (but that's my
> opinion, some chip changes need to happen first)
>
> i also think you're hpl numbers on the amd chip are low, you should be
>> 4000 which would put you closer to intel, but intel will still edge
> out just because it has a higher base clock.
>
> On Wed, Jun 16, 2021 at 1:15 PM Prentice Bisbal via Beowulf
> <beowulf at beowulf.org> wrote:
>> Did anyone else attend this webinar panel discussion with AMD hosted by
>> HPCWire yesterday? It was titled "AMD HPC Solutions: Enabling Your
>> Success in HPC"
>>
>> https://www.hpcwire.com/amd-hpc-solutions-enabling-your-success-in-hpc/
>>
>> I attended it, and noticed there was no mention of AMD supporting
>> AVX512, so during the question and answer portion of the program, I
>> asked when AMD processors will support AVX512. The answer given, and I'm
>> not making this up, is that AMD listens to their users and gives the
>> users what they want, and right now they're not hearing any demand for
>> AVX512.
>>
>> Personally, I call BS on that one. I can't imagine anyone in the HPC
>> community saying "we'd like processors that offer only 1/2 the floating
>> point performance of Intel processors". Sure, AMD can offer more cores,
>> but with only AVX2, you'd need twice as many cores as Intel processors,
>> all other things being equal.
>>
>> Last fall I evaluated potential new cluster nodes for a large cluster
>> purchase using the HPL benchmark. I compared a server with dual AMD EPYC
>> 7H12 processors (128) cores to a server with quad Intel Xeon 8268
>> processors (96 cores). I measured 5,389 GFLOPS for the Xeon 8268, and
>> only 3,446.00 GFLOPS for the AMD 7H12. That's LINPACK score that only
>> 64% of the Xeon 8268 system, despite having 33% more cores.
>>
>>   From what I've heard, the AMD processors run much hotter than the Intel
>> processors, too, so I imagine a FLOPS/Watt comparison would be even less
>> favorable to AMD.
>>
>> An argument can be made that for calculations that lend themselves to
>> vectorization should be done on GPUs, instead of the main processors but
>> the last time I checked, GPU jobs are still memory is limited, and
>> moving data in and out of GPU memory can still take time, so I can see
>> situations where for large amounts of data using CPUs would be preferred
>> over GPUs.
>>
>> Your thoughts?
>>
>> --
>> Prentice
>>
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