On 10/22/20 8:05 PM, Hillf Danton wrote: > On Thu, 22 Oct 2020 08:08:09 -0600 Jens Axboe wrote: >> On 10/22/20 3:02 AM, Zhang,Qiang wrote: >>> >>> Hi Jens Axboe >>> >>> There are some problem in 'io_wqe_worker' thread, when the >>> 'io_wqe_worker' be create and Setting the affinity of CPUs in NUMA >>> nodes, due to CPU hotplug, When the last CPU going down, the >>> 'io_wqe_worker' thread will run anywhere. when the CPU in the node goes >>> online again, we should restore their cpu bindings? >> >> Something like the below should help in ensuring affinities are >> always correct - trigger an affinity set for an online CPU event. We >> should not need to do it for offlining. Can you test it? > > CPU affinity is intact because of nothing to do on offline, and scheduler > will move the stray workers on to the correct NUMA node if any CPU goes > online, so it's a bit hard to see what is going to be tested. Test it yourself: - Boot with > 1 NUMA node - Start an io_uring, you now get 2 workers, each affinitized to a node - Now offline all CPUs in one node - Online one or more of the CPU in that same node The end result is that the worker on the node that was offlined now has a mask of the other node, plus the newly added CPU. So your last statement isn't correct, which is what the original reporter stated. -- Jens Axboe
