linux-kernel - [PATCH] sched/fair: Remove stale references to LAST_BUDDY and SKIP

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Message-ID: <20250314090128.25141-1-vineethr@linux.ibm.com>
Date: Fri, 14 Mar 2025 14:31:28 +0530
From: Madadi Vineeth Reddy <vineethr@...ux.ibm.com>
To: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>,
        Mel Gorman <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
        Adam Li <adamli@...amperecomputing.com>,
        Madadi Vineeth Reddy <vineethr@...ux.ibm.com>
Subject: [PATCH] sched/fair: Remove stale references to LAST_BUDDY and SKIP_BUDDY

Commit 5e963f2bd465 ("sched/fair: Commit to EEVDF") removed the
functionality associated with LAST_BUDDY and SKIP_BUDDY. However,
some outdated references remained in the comments for pick_next_entity
and check_preempt_wakeup_fair. This commit cleans up those comments
to maintain clarity and correctness.

No functional change intended.

Co-developed-by: Adam Li <adamli@...amperecomputing.com>
Signed-off-by: Adam Li <adamli@...amperecomputing.com>
Signed-off-by: Madadi Vineeth Reddy <vineethr@...ux.ibm.com>
---
 kernel/sched/fair.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9dafb374d76d..379dbcbb24e9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5578,8 +5578,6 @@ static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags);
  * Pick the next process, keeping these things in mind, in this order:
  * 1) keep things fair between processes/task groups
  * 2) pick the "next" process, since someone really wants that to run
- * 3) pick the "last" process, for cache locality
- * 4) do not run the "skip" process, if something else is available
  */
 static struct sched_entity *
 pick_next_entity(struct rq *rq, struct cfs_rq *cfs_rq)
@@ -8780,9 +8778,7 @@ static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int
 	 *
 	 * Note: this also catches the edge-case of curr being in a throttled
 	 * group (e.g. via set_curr_task), since update_curr() (in the
-	 * enqueue of curr) will have resulted in resched being set.  This
-	 * prevents us from potentially nominating it as a false LAST_BUDDY
-	 * below.
+	 * enqueue of curr) will have resulted in resched being set.
 	 */
 	if (test_tsk_need_resched(rq->curr))
 		return;
-- 
2.43.5