On 09/18/2018 03:38 PM, Peter Zijlstra wrote: > On Tue, Sep 18, 2018 at 03:22:13PM +0200, Jan H. Schönherr wrote: >> AFAIK, changing the affinity of a cpuset overwrites the individual >> affinities of tasks >> within them. Thus, it shouldn't be an issue. > > No, it only shrinks the set. Also nothing stops you calling > sched_setaffinity() once you're inside the cpuset. The only contraint is > that your mask is a subset of the cpuset mask.
I meant setting the affinity of the cpuset *after* setting an individual affinity. Like this: # mkdir /sys/fs/cgroup/cpuset/test # cat /sys/fs/cgroup/cpuset/cpuset.mems > /sys/fs/cgroup/cpuset/test/cpuset.mems # cat /sys/fs/cgroup/cpuset/cpuset.cpus > /sys/fs/cgroup/cpuset/test/cpuset.cpus # echo $$ > /sys/fs/cgroup/cpuset/test/tasks # taskset -c -p 0 $$ pid 4745's current affinity list: 0-3 pid 4745's new affinity list: 0 # echo "0-1" > /sys/fs/cgroup/cpuset/test/cpuset.cpus # taskset -c -p $$ pid 4745's current affinity list: 0,1 # The individual affinity of $$ is lost, despite it being a subset.
