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

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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: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long 2024-06-03 15:38:22 -04:00 committed by Tejun Heo
parent 018ee567de
commit 1805c1729f
1 changed files with 8 additions and 0 deletions
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8
kernel/cgroup/cpuset.c
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@ -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 */ /* Special case for the 99% of systems with one, full, sched domain */
if (root_load_balance && !top_cpuset.nr_subparts) { if (root_load_balance && !top_cpuset.nr_subparts) {
single_root_domain:
ndoms = 1; ndoms = 1;
doms = alloc_sched_domains(ndoms); doms = alloc_sched_domains(ndoms);
if (!doms) if (!doms)
@ -1022,6 +1023,13 @@ static int generate_sched_domains(cpumask_var_t **domains,
} }
rcu_read_unlock(); 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++) for (i = 0; i < csn; i++)
csa[i]->pn = i; csa[i]->pn = i;
ndoms = csn; ndoms = csn;