cgroup/cpuset: Optimize isolated partition only generate_sched_domain…

…s() 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: Waiman Long <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
torvalds · Jun 3, 2024 · 1805c17 · 1805c17
1 parent 018ee56
commit 1805c17
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
@@ -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;