Compiling for AVX-512
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Profile Keith Myers
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Message 2117 - Posted: 27 Nov 2020, 18:25:03 UTC - in response to Message 2116.
Last modified: 27 Nov 2020, 18:25:24 UTC

OK, should not have used "clone".
Just go to that URL and download the zip file of that branch using the "down" arrow on the green CODE button.

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Ian&Steve C.
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Message 2118 - Posted: 27 Nov 2020, 19:54:48 UTC

If the workloads already easily fit in SSE and AVX/2 register sizes, then expanding to AXV512 won’t have any meaningful benefit. Certainly not the ~2x benefit you’re likely looking for based on synthetic benchmarks.

The source code would have to be changed to send data through the CPU in larger chunks. I don’t think a simple recompile with AVX512 support will automatically make those chunks larger, just gives you the option to throw the same small chunks into the AVX512 path.

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Aurum
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Message 2119 - Posted: 27 Nov 2020, 20:30:48 UTC

https://lemire.me/blog/2018/09/07/avx-512-when-and-how-to-use-these-new-instructions/

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klepel
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Message 2120 - Posted: 30 Nov 2020, 17:07:41 UTC

I know it is slightly off topic, but as it is also about app_config, I would like to force two Ryzen Zen 3 Computers to use “avx” under Windows and “fma” under Linux.
As I am not very knowledge full about app_config, I tried the following for Windows:

<<span class="highlight">app</span>_info> <<span class="highlight">app</span>> <name>gene_pcim</name> </<span class="highlight">app</span>> <file_info> <name>gene_pcim_v1.11_win64__avx</name> <executable/> </file_info> <<span class="highlight">app</span>_version> <<span class="highlight">app</span>_name>gene_pcim</<span class="highlight">app</span>_name> <version_num>110</version_num> <api_version>7.9.0</api_version> <plan_class>avx</plan_class> <flops>5784707816.501904</flops> <avg_ncpus>1.000000</avg_ncpus> <file_ref> <file_name>gene_pcim_v1.11_win64__avx</file_name> <main_program/> </file_ref> </<span class="highlight">app</span>_version> </<span class="highlight">app</span>_info>

And it does not work. Any ideas?
Thanks,
klepel

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Profile Keith Myers
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Message 2121 - Posted: 30 Nov 2020, 23:17:25 UTC - in response to Message 2120.

Can't be done in app_config. Needs to be done in app_info.

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Profile [VENETO] boboviz
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Message 2443 - Posted: 6 Jan 2022, 11:31:23 UTC

Intel is abandoning avx512

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Aurum
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Message 2444 - Posted: 6 Jan 2022, 14:30:47 UTC - in response to Message 2443.

Intel is abandoning avx512
"...so if you are able to make use of AVX-512 support, you’d best not upgrade your BIOS from now on if you can help it."
I wonder if they're going to disable AVX-512 for previous generations.
I only run fma for TN-GRID. Are there BOINC projects that benefit with from AVX-512?

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Message 2445 - Posted: 6 Jan 2022, 19:18:54 UTC - in response to Message 2444.

Are there BOINC projects that benefit with from AVX-512?


The PrimeGrid LLR subprojects will use avx-512.

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Profile [VENETO] boboviz
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Message 2448 - Posted: 7 Jan 2022, 14:02:10 UTC - in response to Message 2444.
Last modified: 7 Jan 2022, 14:03:19 UTC

I only run fma for TN-GRID. Are there BOINC projects that benefit with from AVX-512?


If i'm not wrong, no.
Up to now. there are not boinc projects with avx-512 support

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Profile [VENETO] boboviz
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Message 2449 - Posted: 7 Jan 2022, 14:02:34 UTC - in response to Message 2448.
Last modified: 7 Jan 2022, 14:03:03 UTC

double message

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Ian&Steve C.
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Message 2450 - Posted: 7 Jan 2022, 17:43:26 UTC - in response to Message 2444.

Intel is abandoning avx512
"...so if you are able to make use of AVX-512 support, you’d best not upgrade your BIOS from now on if you can help it."
I wonder if they're going to disable AVX-512 for previous generations.
I only run fma for TN-GRID. Are there BOINC projects that benefit with from AVX-512?


so i guess you never figured out a proper app_info.xml file to get your homegrown app to work with BOINC? or you did and the avx512 app didn't provide any benefit?

honestly the easiest way to roll your own app is to just rename it to the exact same file name as the stock app, set the <dont_check_file_sizes> flag in cc_config.xml, and let the new app masquerade as the old app. BOINC will call it and run it thinking it's the stock app, but running your own binary. if you don't set the <dont_check_file_sizes> flag, BOINC will detect the change and erase it and re-download another fresh stock app from the project.

that's assuming that the project stock apps don't have some kind of signature/key checking in place (this bit me with a modified Einstein app, so had to use a different method to inject code changes on the fly).

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Profile [VENETO] boboviz
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Message 2451 - Posted: 7 Jan 2022, 19:23:24 UTC - in response to Message 2450.

or you did and the avx512 app didn't provide any benefit?


Some times ago, Linus Torvalds explained his thought about Axv512: "I Hope AVX512 Dies A Painful Death" :-P

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