linux-kernel - [PATCH 1/6] Revert "sched_ext: Use shorter slice while bypassing"

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Message-ID: <20241009214411.681233-2-tj@kernel.org>
Date: Wed,  9 Oct 2024 11:40:57 -1000
From: Tejun Heo <tj@...nel.org>
To: void@...ifault.com
Cc: kernel-team@...a.com,
	linux-kernel@...r.kernel.org,
	sched-ext@...a.com,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 1/6] Revert "sched_ext: Use shorter slice while bypassing"

This reverts commit 6f34d8d382d64e7d8e77f5a9ddfd06f4c04937b0.

Slice length is ignored while bypassing and tasks are switched on every tick
and thus the patch does not make any difference. The perceived difference
was from test noise.

Signed-off-by: Tejun Heo <tj@...nel.org>
---
 kernel/sched/ext.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 22e18aec4ee1..e08cfba33cb4 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -9,7 +9,6 @@
 #define SCX_OP_IDX(op)		(offsetof(struct sched_ext_ops, op) / sizeof(void (*)(void)))
 
 enum scx_consts {
-	SCX_SLICE_BYPASS		= SCX_SLICE_DFL / 4,
 	SCX_DSP_DFL_MAX_BATCH		= 32,
 	SCX_DSP_MAX_LOOPS		= 32,
 	SCX_WATCHDOG_MAX_TIMEOUT	= 30 * HZ,
@@ -1949,7 +1948,6 @@ static bool scx_rq_online(struct rq *rq)
 static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 			    int sticky_cpu)
 {
-	bool bypassing = scx_rq_bypassing(rq);
 	struct task_struct **ddsp_taskp;
 	unsigned long qseq;
 
@@ -1967,7 +1965,7 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 	if (!scx_rq_online(rq))
 		goto local;
 
-	if (bypassing)
+	if (scx_rq_bypassing(rq))
 		goto global;
 
 	if (p->scx.ddsp_dsq_id != SCX_DSQ_INVALID)
@@ -2022,7 +2020,7 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 
 global:
 	touch_core_sched(rq, p);	/* see the comment in local: */
-	p->scx.slice = bypassing ? SCX_SLICE_BYPASS : SCX_SLICE_DFL;
+	p->scx.slice = SCX_SLICE_DFL;
 	dispatch_enqueue(find_global_dsq(p), p, enq_flags);
 }
 
-- 
2.46.2