I forgot that the cpuset value is still available in cgroups v2. You would want the cpuset.cpus.effective value. More information is available here: https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html
On Mon, Aug 31, 2020 at 11:19 AM Guy Streeter <guy.stree...@gmail.com> wrote: > > As I said, cgroups doesn't limit the group to a number of cores, it > limits processing time, either as an absolute amount or as a share of > what is available. > A docker process can be restricted to a set of cores, but that is done > with cpu affinity, not cgroups. > > You could try to figure out an equivalency. For instance if you are > using cpu.shares to limit the cgroups, then figure the ratio of a > cgroup's share to the shares of all the cgroups at that level, and > apply that ratio to the number of available cores to get an estimated > number of threads you should start. > > On Mon, Aug 31, 2020 at 10:40 AM Brock Palen <bro...@umich.edu> wrote: > > > > Sorry if wasn't clear, I'm trying to find out what is available to my > > process before it starts up threads. If the user is jailed in a cgroup > > (docker, slurm, other) and the program tries to start 36 threads, when it > > only has access to 4 cores, it's probably not a huge deal, but not > > desirable. > > > > I do allow the user to specify number of threads, but would like to > > automate it for least astonishment. > > > > Brock Palen > > IG: brockpalen1984 > > www.umich.edu/~brockp > > Director Advanced Research Computing - TS > > bro...@umich.edu > > (734)936-1985 > > > > > > On Mon, Aug 31, 2020 at 11:34 AM Guy Streeter <guy.stree...@gmail.com> > > wrote: > >> > >> My very basic understanding of cgroups is that it can be used to limit > >> cpu processing time for a group, and to ensure fair distribution of > >> processing time within the group, but I don't know of a way to use > >> cgroups to limit the number of CPUs available to a cgroup. > >> > >> On Mon, Aug 31, 2020 at 8:56 AM Brock Palen <bro...@umich.edu> wrote: > >> > > >> > Hello, > >> > > >> > I have a small utility, it is currently using multiprocess.cpu_count() > >> > Which currently ignores cgroups etc. > >> > > >> > I see https://gitlab.com/guystreeter/python-hwloc > >> > But appears stale, > >> > > >> > How would you detect number of threads that are safe to start in a > >> > cgroup from Python3 ? > >> > > >> > Thanks! > >> > > >> > Brock Palen > >> > IG: brockpalen1984 > >> > www.umich.edu/~brockp > >> > Director Advanced Research Computing - TS > >> > bro...@umich.edu > >> > (734)936-1985 > >> > _______________________________________________ > >> > hwloc-users mailing list > >> > hwloc-users@lists.open-mpi.org > >> > https://lists.open-mpi.org/mailman/listinfo/hwloc-users > >> _______________________________________________ > >> hwloc-users mailing list > >> hwloc-users@lists.open-mpi.org > >> https://lists.open-mpi.org/mailman/listinfo/hwloc-users > > > > _______________________________________________ > > hwloc-users mailing list > > hwloc-users@lists.open-mpi.org > > https://lists.open-mpi.org/mailman/listinfo/hwloc-users _______________________________________________ hwloc-users mailing list hwloc-users@lists.open-mpi.org https://lists.open-mpi.org/mailman/listinfo/hwloc-users
