Posts by floyd
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1) Message boards : Number crunching : FMA application for windows_x86_64 (Message 2189)
Posted 2 Feb 2021 by floyd
It happens that the performances of the various versions are almost the same.

I am not so sure about that! I observed: tn-grid Server starts to send out only one App type to a certain computer after a while and does not send other Apps to re-check from time to time, if another App type would work better.

In my experience that happens when one application seems(!) to be much faster than the others. For example my 1700X gets FMA tasks exclusively after a short start phase, because BOINC rated AVX and SSE2 around 5.4 GFLOPS but FMA above 7. The reason for that is not that the application is really much faster but I experimented with system configuration during the evaluation phase. Now in regular operation the experienced speed of FMA drops towards the other applications. I wonder what will happen when they are about equal. Maybe BOINC will start trying other applications again.

I have also observed, when I bring a new computer online with a mix of tn-grid WUs and Climateprediction.net WUs, the tn-grid server starts to send out only sse2 WUs to this particular computer

I always seem to get a batch of the same type initially but other types soon after. On my computers, other than the 1700X, I still get a mix of applications after some weeks. BOINC hasn't found a favourite yet and it looks like it won't. Speed differences are small and the relative speeds keep changing.

AMD 3950x (RAM 3600, 32 GB, Linux): sse2 (this computer here with similar characteristics: http://gene.disi.unitn.it/test/results.php?hostid=64788 and here: http://gene.disi.unitn.it/test/results.php?hostid=60351, fma, and they are 500 [s] faster)

See the application statistics for those hosts:
http://gene.disi.unitn.it/test/host_app_versions.php?hostid=64788
http://gene.disi.unitn.it/test/host_app_versions.php?hostid=60351
You'll notice that the speed difference between the fastest and the slowest application is about 2% or less. That's also my own experience. For the difference between those computers and yours there's more likely reasons. System load and clocks come to mind immediately.

This is why I asked for an working app_config to select a particular App type for tn-grid. Unfortunately, I never worked it out!

You can't do that with app_config. You'd need to run an Anonymous Platform via app_info but that's tricky. I suggest you don't touch that without a better reason.




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