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[3/4] lib/group_cpus: optimize inner loop in grp_spread_init_one()

Message ID 20231101225820.51342-4-yury.norov@gmail.com
State New
Headers
Series lib/group_cpus: rework grp_spread_init_one() and make it O(1) |

Commit Message

Yury Norov Nov. 1, 2023, 10:58 p.m. UTC 
  The loop starts from the beginning every time we switch to the next
sibling mask. This is the Schlemiel the Painter's style of coding
because we know for sure that nmsk is clear up to current CPU, and we
can just continue from the next CPU.

Also, we can do it nicer if leverage the dedicated for_each() iterator.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 lib/group_cpus.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/lib/group_cpus.c b/lib/group_cpus.c
index b1e7d9cc9da9..8afe0c71d204 100644
--- a/lib/group_cpus.c
+++ b/lib/group_cpus.c
@@ -30,13 +30,13 @@  static void grp_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
 
 		/* If the cpu has siblings, use them first */
 		siblmsk = topology_sibling_cpumask(cpu);
-		for (sibl = -1; cpus_per_grp > 0; ) {
-			sibl = cpumask_next(sibl, siblmsk);
-			if (sibl >= nr_cpu_ids)
-				break;
+		sibl = cpu + 1;
+
+		for_each_cpu_and_from(sibl, siblmsk, nmsk) {
 			__cpumask_clear_cpu(sibl, nmsk);
 			__cpumask_set_cpu(sibl, irqmsk);
-			cpus_per_grp--;
+			if (cpus_per_grp-- == 0)
+				return;
 		}
 	}
 }