A single partition setup and tear-down operation can lead to multiple rebuild_sched_domains_locked() calls which is a waste of effort. This can partly be mitigated by adding a flag to suppress the rebuild_sched_domains_locked() call in update_cpumasks_hier(). Since a Boolean flag has already been passed as the 3rd argument to update_cpumasks_hier(), we can extend that to a full flag word.
The sched domain rebuild suppression is now enabled in update_sibling_cpumasks() as all it callers will do the sched domain rebuild after its return later on anyway.
Signed-off-by: Waiman Long longman@redhat.com --- kernel/cgroup/cpuset.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index b8ccc1be7bde..64f9e305b3ab 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1590,6 +1590,12 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, return 0; }
+/* + * update_cpumasks_hier() flags + */ +#define HIER_CHECKALL 0x01 /* Check all cpusets with no skipping */ +#define HIER_NO_SD_REBUILD 0x02 /* Don't rebuild sched domains */ + /* * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree * @cs: the cpuset to consider @@ -1604,7 +1610,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, * Called with cpuset_mutex held */ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, - bool force) + int flags) { struct cpuset *cp; struct cgroup_subsys_state *pos_css; @@ -1644,10 +1650,10 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, * Skip the whole subtree if * 1) the cpumask remains the same, * 2) has no partition root state, - * 3) force flag not set, and + * 3) HIER_CHECKALL flag not set, and * 4) for v2 load balance state same as its parent. */ - if (!cp->partition_root_state && !force && + if (!cp->partition_root_state && !(flags & HIER_CHECKALL) && cpumask_equal(tmp->new_cpus, cp->effective_cpus) && (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) || (is_sched_load_balance(parent) == is_sched_load_balance(cp)))) { @@ -1764,7 +1770,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, } rcu_read_unlock();
- if (need_rebuild_sched_domains) + if (need_rebuild_sched_domains && !(flags & HIER_NO_SD_REBUILD)) rebuild_sched_domains_locked(); }
@@ -1788,7 +1794,9 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs, * to use the right effective_cpus value. * * The update_cpumasks_hier() function may sleep. So we have to - * release the RCU read lock before calling it. + * release the RCU read lock before calling it. HIER_NO_SD_REBUILD + * flag is used to suppress rebuild of sched domains as the callers + * will take care of that. */ rcu_read_lock(); cpuset_for_each_child(sibling, pos_css, parent) { @@ -1800,7 +1808,7 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs, continue;
rcu_read_unlock(); - update_cpumasks_hier(sibling, tmp, false); + update_cpumasks_hier(sibling, tmp, HIER_NO_SD_REBUILD); rcu_read_lock(); css_put(&sibling->css); } @@ -1913,7 +1921,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, spin_unlock_irq(&callback_lock);
/* effective_cpus will be updated here */ - update_cpumasks_hier(cs, &tmp, false); + update_cpumasks_hier(cs, &tmp, 0);
if (cs->partition_root_state) { struct cpuset *parent = parent_cs(cs); @@ -2382,7 +2390,7 @@ static int update_prstate(struct cpuset *cs, int new_prs) * Force update if switching back to member. */ if (!list_empty(&cs->css.children)) - update_cpumasks_hier(cs, &tmpmask, !new_prs); + update_cpumasks_hier(cs, &tmpmask, !new_prs ? HIER_CHECKALL : 0);
/* Update sched domains and load balance flag */ update_partition_sd_lb(cs, old_prs);