We're running Fedora 19 with the 3.11.10-200.fc19.x86_64 kernel (just the normal RPM) on large servers (128GB RAM over two NUMA regions, each with one hex-core processor) with a large number of processes (more than 700, a couple hundred of which are active fairly frequently). We encounter situations where there system gets overwhelmed with migrate/N tasks from the kernel, based on what we've seen in top. Here's what we've tried: * tuned-adm on latency-performance and virtual-host profiles * kernel.sched_migration_cost_ns=5000000 (which tuned will do for those profiles in v3.3/Fedora 20) * numad Here's what we've used for analysis: * powertop * top/htop * perf record -a -g * SystemTap with code to print out migrations occurring * numatop All we know is that the migration storms correlate with concurrent Chef runs verifying/configuring containers on the system. Obviously, Chef invokes many things. But, most of the migrations we see are for Chef, the Ruby interpreter, the sh interpreter, and Munin. Responsiveness returns to normal after SystemTap reports a large set of chef-solo migrations, presumably at their completion. David Strauss Pantheon Systems Fedora Server Working Group _______________________________________________ kernel mailing list kernel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/kernel
