On Tue, Nov 23, 2021 at 8:10 AM Mina Almasry <almasrymina@xxxxxxxxxx> wrote: > > For hugetlb backed jobs/VMs it's critical to understand the numa > information for the memory backing these jobs to deliver optimal > performance. > > Currently this technically can be queried from /proc/self/numa_maps, but > there are significant issues with that. Namely: > 1. Memory can be mapped or unmapped. > 2. numa_maps are per process and need to be aggregated across all > processes in the cgroup. For shared memory this is more involved as > the userspace needs to make sure it doesn't double count shared > mappings. > 3. I believe querying numa_maps needs to hold the mmap_lock which adds > to the contention on this lock. > > For these reasons I propose simply adding hugetlb.*.numa_stat file, > which shows the numa information of the cgroup similarly to > memory.numa_stat. > > On cgroup-v2: > cat /sys/fs/cgroup/unified/test/hugetlb.2MB.numa_stat > total=2097152 N0=2097152 N1=0 > > On cgroup-v1: > cat /sys/fs/cgroup/hugetlb/test/hugetlb.2MB.numa_stat > total=2097152 N0=2097152 N1=0 > hierarichal_total=2097152 N0=2097152 N1=0 > > This patch was tested manually by allocating hugetlb memory and querying > the hugetlb.*.numa_stat file of the cgroup and its parents. >  > Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Shuah Khan <shuah@xxxxxxxxxx> > Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx> > Cc: Oscar Salvador <osalvador@xxxxxxx> > Cc: Michal Hocko <mhocko@xxxxxxxx> > Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx> > Cc: David Rientjes <rientjes@xxxxxxxxxx> > Cc: Shakeel Butt <shakeelb@xxxxxxxxxx> > Cc: Jue Wang <juew@xxxxxxxxxx> > Cc: Yang Yao <ygyao@xxxxxxxxxx> > Cc: Joanna Li <joannali@xxxxxxxxxx> > Cc: Cannon Matthews <cannonmatthews@xxxxxxxxxx> > Cc: linux-mm@xxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > > Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx> Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
