From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 3 Apr 2024 07:50:07 +0000 (+0200)
Subject: sched/fair: Cleanup pick_task_fair() vs throttle
X-Git-Tag: v6.12-rc1~120^2~41
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=8e2e13ac6122915bd98315237b0317495e391be0;p=linux-block.git

sched/fair: Cleanup pick_task_fair() vs throttle

Per 54d27365cae8 ("sched/fair: Prevent throttling in early
pick_next_task_fair()") the reason check_cfs_rq_runtime() is under the
'if (curr)' check is to ensure the (downward) traversal does not
result in an empty cfs_rq.

But then the pick_task_fair() 'copy' of all this made it restart the
traversal anyway, so that seems to solve the issue too.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lkml.kernel.org/r/20240727105028.501679876@infradead.org
---

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 8201f0f4e709..7ba1ca56a63e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8471,11 +8471,11 @@ again:
 				update_curr(cfs_rq);
 			else
 				curr = NULL;
-
-			if (unlikely(check_cfs_rq_runtime(cfs_rq)))
-				goto again;
 		}
 
+		if (unlikely(check_cfs_rq_runtime(cfs_rq)))
+			goto again;
+
 		se = pick_next_entity(cfs_rq);
 		cfs_rq = group_cfs_rq(se);
 	} while (cfs_rq);