diff options
| -rw-r--r-- | kernel/cgroup/cpuset.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 2525905cdf48..b8361f55ef36 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2513,12 +2513,28 @@ static void cpuset_attach(struct cgroup_taskset *tset) struct cgroup_subsys_state *css; struct cpuset *cs; struct cpuset *oldcs = cpuset_attach_old_cs; + bool cpus_updated, mems_updated; cgroup_taskset_first(tset, &css); cs = css_cs(css); lockdep_assert_cpus_held(); /* see cgroup_attach_lock() */ percpu_down_write(&cpuset_rwsem); + cpus_updated = !cpumask_equal(cs->effective_cpus, + oldcs->effective_cpus); + mems_updated = !nodes_equal(cs->effective_mems, oldcs->effective_mems); + + /* + * In the default hierarchy, enabling cpuset in the child cgroups + * will trigger a number of cpuset_attach() calls with no change + * in effective cpus and mems. In that case, we can optimize out + * by skipping the task iteration and update. + */ + if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && + !cpus_updated && !mems_updated) { + cpuset_attach_nodemask_to = cs->effective_mems; + goto out; + } guarantee_online_mems(cs, &cpuset_attach_nodemask_to); @@ -2539,9 +2555,14 @@ static void cpuset_attach(struct cgroup_taskset *tset) /* * Change mm for all threadgroup leaders. This is expensive and may - * sleep and should be moved outside migration path proper. + * sleep and should be moved outside migration path proper. Skip it + * if there is no change in effective_mems and CS_MEMORY_MIGRATE is + * not set. */ cpuset_attach_nodemask_to = cs->effective_mems; + if (!is_memory_migrate(cs) && !mems_updated) + goto out; + cgroup_taskset_for_each_leader(leader, css, tset) { struct mm_struct *mm = get_task_mm(leader); @@ -2564,6 +2585,7 @@ static void cpuset_attach(struct cgroup_taskset *tset) } } +out: cs->old_mems_allowed = cpuset_attach_nodemask_to; cs->attach_in_progress--; |