Posts by Ian&Steve C.

1) Message boards : Number crunching : Compiling for AVX-512 (Message 2450)
Posted 7 Jan 2022 by Ian&Steve C.

Intel is abandoning avx512
"...so if you are able to make use of AVX-512 support, youâ€™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).

2) Message boards : Number crunching : Compiling for AVX-512 (Message 2118)
Posted 27 Nov 2020 by Ian&Steve C.

If the workloads already easily fit in SSE and AVX/2 register sizes, then expanding to AXV512 wonâ€™t have any meaningful benefit. Certainly not the ~2x benefit youâ€™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 donâ€™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.