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Strange slow down and affinity !
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Mahmoud Uthman



Joined: 17 Jan 2015
Posts: 190

PostPost subject: Re: Strange slow down and affinity !    Posted: Mon Jun 19, 2017 11:53 am Reply to topic Reply with quote

jdart wrote:
Some multi-core engines have support for setting affinity (pinning threads to cores). I have not actually seen a big benefit from it in my testing, but YMMV.

It can be hard to do this portably. I use the hwloc library for this. Some other issues: logical vs physical cores (hyperthreading) - not always easy to distinguish these and you need to decide what your strategy is for that. Also core numbering is not standardized. Pinning works fine if one engine is using all cores on a machine, but if using multiple engines each with affinity support it can get tricky because they do it different ways.

--Jon

Mine isn't multithreaded , so it even affects single threaded heavily when the OS manages it in a bad way , another thing that elevated the problem was setting the process priority to real-time , but setting the affinity still produced better performance.
Is there no way to ask the OS to keep us on the same core/s if possible instead of hardcoded affinity "to avoid load balancing problems too"?
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Subject Author Date/Time
Strange slow down and affinity ! Mahmoud Uthman Mon Jun 19, 2017 8:10 am
      Re: Strange slow down and affinity ! Jon Dart Mon Jun 19, 2017 9:57 am
            Re: Strange slow down and affinity ! Mahmoud Uthman Mon Jun 19, 2017 11:53 am
      Re: Strange slow down and affinity ! Ferdinand Mosca Mon Jun 19, 2017 12:30 pm
            Re: Strange slow down and affinity ! Mahmoud Uthman Mon Jun 19, 2017 1:05 pm
                  Re: Strange slow down and affinity ! Ferdinand Mosca Mon Jun 19, 2017 1:43 pm
      Re: Strange slow down and affinity ! Ed Schroder Mon Jun 19, 2017 1:49 pm
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