Glauber Costa wrote: > Turns out that most of the infrastructure we need to put two controllers in the > same hierarchy is by far already into place. All we need to do is not failing > when we specify two of them. > You don't need to change anything to mount with 2 cgroup subsystems: # mount -t cgroup -o cpu,cpuacct xxx /mnt But you may want to revise and make use of the subsys->bind() callback, which is called at mount/remount/umount when we attach/remove a controller to/from a hierarchy. It's the place you can check if two controllers are going to be comounted/seperated. > With this, we can effectively guarantee that by comounting cpu and cpuacct, > we'll have the same set of tasks, therefore allowing us to use cpu cgroup data > to fill in the usage fields in cpuacct. > > I decided not to stabilish any dependency between cgroups as Li previously did: > cgroups may or may not be comounted, and any of them can be combined (I don't > see a reason to prevent any combination). > > After testing and some trials, I could verify that the current mount behavior > plays well under the plans, so I didn't change it. That is: > > * If subsystems A and B aren't mounted, we can comount them. > * If subsystem A is mounted, but B is not: > * we can comount them if A has no children, > * we fail otherwise > * If subsystems A and B are comounted at a location, we can't > mount any of them separately at another point. We do can mount > them together. > * If subsystems A and B are comounted at a location, > * we can comount a third subsystem C, if they have no children > * we fail otherwise > > Paul, > > Please let me know if this is tuned with the idea you had in mind. > If this is okay, I patch that extracts usage from cpu cgroup data > in case of comount would follow. > > Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx> > CC: Paul Turner <pjt@xxxxxxxxxx> > CC: Li Zefan <lizf@xxxxxxxxxxxxxx> > --- > kernel/cgroup.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index 1fd7867..e894a4f 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -1211,9 +1211,9 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) > set_bit(i, &opts->subsys_bits); > one_ss = true; > > - break; > + continue; > } > - if (i == CGROUP_SUBSYS_COUNT) > + if (opts->subsys_bits == 0) > return -ENOENT; > } > -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
