Peter Zijlstra wrote: > On Fri, 2010-10-22 at 16:09 +0800, Li Zefan wrote: >> Stephane posted a patchset to add perf_cgroup subsystem, so perf can >> be used to monitor all threads belonging to a cgroup. >> >> But if you already mounted a cgroup hierarchy but without perf_cgroup >> and the hierarchy has sub-cgroups, you can't bind perf_cgroup to it, >> and thus you're not able to use per-cgroup perf feature. >> >> This patchset alleviates the pain, and then a subsytem can be >> bound/unbound to/from a hierarchy which has sub-cgroups in it. >> >> Some subsystems still can't take advantage of this patchset, memcgroup >> and cpuset in specific. >> >> For cpuset, if a hierarchy has a sub-cgroup and the cgroup has tasks, >> we can't decide sub-cgroup's cpuset.mems and cpuset.cpus automatically >> if we try to bind cpuset to this hierarchy. >> >> For memcgroup, memcgroup uses css_get/put(), and due to some complexity, >> for now bindable subsystems should not use css_get/put(). >> >> Usage: >> >> # mount -t cgroup -o cpuset xxx /mnt >> # mkdir /mnt/tmp >> # echo $$ > /mnt/tmp/tasks >> >> (add cpuacct to the hierarchy) >> # mount -o remount,cpuset,cpuacct xxx /mnt >> >> (remove it from the hierarchy) >> # mount -o remount,cpuset xxx /mnt >> >> There's another limitation, cpuacct should not be bound to any mounted >> hierarchy before the above operation. But that's not a problem, as you >> can remove it from a hierarchy and bind it to another one. > > Right, so the only remaining problem I see with this approach is that > you cannot profile two different hierarchies at the same time, but I > can't really think of a solution to that problem (nor do I care very > much). > Paul had a patch to allow some subsystems to be added to multi-hierarchies, which may help. But it forbids accessing t->cgroups, which makes this feature of limited use. Anyway I too don't care much about this. > Seems like a nice approach, Thanks Li! > Thanks! _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
