CPU FAH core with AVX support? Mentioned a while back?

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Re: CPU FAH core with AVX support? Mentioned a while back?

Postby 7im » Mon Nov 07, 2016 2:54 pm

Good for you.

Please note that the a7 core also supports non-AVX hardware.
(It will use the AVX feature if your hardware supports it but will not object if you don't.)
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Re: CPU FAH core with AVX support? Mentioned a while back?

Postby anandhanju » Thu Apr 05, 2018 5:09 am

Is there a performance benefit if the CPU has AVX2 support? These extensions are available in CPUs using the Haswell micro-architecture and successors. Per this GROMACS page, there is an AVX2_256 SIMD mode. However, my logs indicate AVX_256, not AVX2_256, is being used. Assuming these are compile time flags that we, Folders, cannot control, is there a possibility that cores with AVX2_256 on supported CPUs could run faster?

Code: Select all
01:03:13:WU00:FS00:0xa7:************************** Gromacs Folding@home Core ***************************
01:03:13:WU00:FS00:0xa7:       Type: 0xa7
01:03:13:WU00:FS00:0xa7:       Core: Gromacs
01:03:13:WU00:FS00:0xa7:    Website: http://folding.stanford.edu/
01:03:13:WU00:FS00:0xa7:  Copyright: (c) 2009-2016 Stanford University
01:03:13:WU00:FS00:0xa7:     Author: Joseph Coffland <joseph@cauldrondevelopment.com>
01:03:13:WU00:FS00:0xa7:       Args: -dir 00 -suffix 01 -version 704 -lifeline 114772 -checkpoint 15 -np
01:03:13:WU00:FS00:0xa7:             4
01:03:13:WU00:FS00:0xa7:     Config: <none>
01:03:13:WU00:FS00:0xa7:************************************ Build *************************************
01:03:13:WU00:FS00:0xa7:    Version: 0.0.16
01:03:13:WU00:FS00:0xa7:       Date: Oct 31 2017
01:03:13:WU00:FS00:0xa7:       Time: 19:24:09
01:03:13:WU00:FS00:0xa7: Repository: Git
01:03:13:WU00:FS00:0xa7:   Revision: 2f0a8a3d0b0698be48154fe99a0216f289060932
01:03:13:WU00:FS00:0xa7:     Branch: master
01:03:13:WU00:FS00:0xa7:   Compiler: GNU 4.9.2
01:03:13:WU00:FS00:0xa7:    Options: -std=gnu++98 -O3 -funroll-loops
01:03:13:WU00:FS00:0xa7:   Platform: linux2 4.9.0-1-amd64
01:03:13:WU00:FS00:0xa7:       Bits: 64
01:03:13:WU00:FS00:0xa7:       Mode: Release
01:03:13:WU00:FS00:0xa7:       SIMD: avx_256
01:03:13:WU00:FS00:0xa7:************************************ System ************************************
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Re: CPU FAH core with AVX support? Mentioned a while back?

Postby foldy » Thu Apr 05, 2018 10:09 am

For AMD Ryzen CPUs AVX2_128 would be the fastest which gets supported in Gromacs 2018 now.
http://manual.gromacs.org/documentation ... -amd-ryzen
I guess the next fah cpu core will support this avx2 because it seems you get this out of the box.
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Re: CPU FAH core with AVX support? Mentioned a while back?

Postby toTOW » Sat Apr 07, 2018 4:31 pm

anandhanju wrote:Is there a performance benefit if the CPU has AVX2 support?

No, the core is compiled to use only AVX.
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Re: CPU FAH core with AVX support? Mentioned a while back?

Postby JimboPalmer » Sun Apr 08, 2018 12:28 am

anandhanju wrote:Is there a performance benefit if the CPU has AVX2 support?

It will run faster, so get more points than on a CPU that does not support AVX2, where it will use SSE2.
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Re: CPU FAH core with AVX support? Mentioned a while back?

Postby bruce » Sun Apr 08, 2018 11:19 pm

At the time FAHCore_a7 was created, GROMACS required the platform to defined at compile time. Thus FAH had to compile two differernt versions and add the intelligence to FAHClient to choose the right one. One version supports SSE2 and the other version supports AVX. The added complexity to detect all variations and load a full spectrum of versions wasn't worth the extra complexity that would have been required for a relatively small gain on a limited number of machines.

From what I read, a later version of GROMACS has been developed that detects and loads support for more options. That might come in FAHCore_a9 if one is developed before something else happens, but FAH has limited development resources so I don't expect we'll see that any time soon.

The added performance was probably not the primary reason for developing FAHCore_a7, though it's certainly nice. Core A7 uses a newer version of GROMACS (compared to FAHCore_a4) which has added some scientific functionality. This allows additional options in building the model of a protein and I expect that was a higher priority reason.
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Re: CPU FAH core with AVX support? Mentioned a while back?

Postby anandhanju » Mon Apr 09, 2018 1:20 pm

Good to know. Thanks bruce!
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Re: CPU FAH core with AVX support? Mentioned a while back?

Postby JimboPalmer » Mon Apr 09, 2018 3:21 pm

As Bruce mentioned, At one point in the testing, there were two versions a7 and a8, which then both got rolled up into a7. If there is a new test version I would expect it to be a9. (then aa? or b0? or the ugly a10? the suspense is killing me)
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Re: CPU FAH core with AVX support? Mentioned a while back?

Postby Nathan_P » Wed Apr 11, 2018 1:16 pm

JimboPalmer wrote:As Bruce mentioned, At one point in the testing, there were two versions a7 and a8, which then both got rolled up into a7. If there is a new test version I would expect it to be a9. (then aa? or b0? or the ugly a10? the suspense is killing me)


I suspect b0, wasn't the protomol core b4? And good to know what happened with a8, I did wonder from time to time where that had gone.
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