Hi Kamezawa-san and Kosaki-san, > > I have a suggestion for css_id numbering. How about using the same > > numbering scheme as process ID for css_id instead of idr? It prevents > > the same ID from being reused quickly. > > process ID is not "short"(2bytes). > > > blkio-cgroup can benefit from it. If some pages still have an old ID, > > it can somewhat prevents IOs associated with those pages from being > > charged for a new cgroup which are reusing the old ID. > > plz see memcg's code. no reuse if id is still used. blkio-cgroup embeds css_id into page_cgroup->flags, and the ID in the flags still remain even after the cgroup which marks up the page is removed. The current numbering scheme of css_id choose the lowest number from available IDs. When a cgroup is created right after another cgroup is removed (no one referes to the cgroup), the same number will be reused for the new cgroup. When an IO associated with the page is issued, an IO controller which uses blkio-cgroup charges the new cgroup according to the ID in the page_cgroup->flags, instead of the removed cgroup. If css_id is simply incremented by one like process ID, I think we could avoid such wrong charges in many cases. > it seems bogus solusion. > pid rule also can make conflict. I think blkio-cgroup should be fixed. This solution is reasonable for accuracy, even conflicts occur. I think keeping down the overhead of blkio-cgroup is more important. Thanks, Ryo Tsuruta _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers