Commit bcd74b2f authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched/fair: Only set slice protection at pick time 



We should not (re)set slice protection in the sched_change pattern
which calls put_prev_task() / set_next_task().

Fixes: 63304558 ("sched/eevdf: Curb wakeup-preemption")
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Tested-by: default avatarK Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: default avatarShubhang Kaushik <shubhang@os.amperecomputing.com>
Link: https://patch.msgid.link/20260219080624.561421378%40infradead.org
parent b3d99f43

kernel/sched/fair.c

+6 −5
Original line number Diff line number Diff line
@@ -5445,7 +5445,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) 
}



static void

set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)

set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, bool first)

{

	clear_buddies(cfs_rq, se);
@@ -5460,6 +5460,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) 
		__dequeue_entity(cfs_rq, se);

		update_load_avg(cfs_rq, se, UPDATE_TG);



		if (first)

			set_protect_slice(cfs_rq, se);

	}
@@ -8978,13 +8979,13 @@ pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf 
				pse = parent_entity(pse);

			}

			if (se_depth >= pse_depth) {

				set_next_entity(cfs_rq_of(se), se);

				set_next_entity(cfs_rq_of(se), se, true);

				se = parent_entity(se);

			}

		}



		put_prev_entity(cfs_rq, pse);

		set_next_entity(cfs_rq, se);

		set_next_entity(cfs_rq, se, true);



		__set_next_task_fair(rq, p, true);

	}
@@ -13598,7 +13599,7 @@ static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first) 
	for_each_sched_entity(se) {

		struct cfs_rq *cfs_rq = cfs_rq_of(se);



		set_next_entity(cfs_rq, se);

		set_next_entity(cfs_rq, se, first);

		/* ensure bandwidth has been allocated on our new cfs_rq */

		account_cfs_rq_runtime(cfs_rq, 0);

	}