Commit 1805c172 authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
Browse files

cgroup/cpuset: Optimize isolated partition only generate_sched_domains() calls 



If only isolated partitions are being created underneath the cgroup root,
there will only be one sched domain with top_cpuset.effective_cpus. We can
skip the unnecessary sched domains scanning code and save some cycles.

Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 018ee567

kernel/cgroup/cpuset.c

+8 −0
Original line number Diff line number Diff line
@@ -964,6 +964,7 @@ static int generate_sched_domains(cpumask_var_t **domains, 


	/* Special case for the 99% of systems with one, full, sched domain */

	if (root_load_balance && !top_cpuset.nr_subparts) {

single_root_domain:

		ndoms = 1;

		doms = alloc_sched_domains(ndoms);

		if (!doms)
@@ -1022,6 +1023,13 @@ static int generate_sched_domains(cpumask_var_t **domains, 
	}

	rcu_read_unlock();



	/*

	 * If there are only isolated partitions underneath the cgroup root,

	 * we can optimize out unneeded sched domains scanning.

	 */

	if (root_load_balance && (csn == 1))

		goto single_root_domain;



	for (i = 0; i < csn; i++)

		csa[i]->pn = i;

	ndoms = csn;