From: "tip-bot2 for Kirill Tkhai" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
x86 <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: [tip: sched/core] sched: Micro optimization in pick_next_task() and in check_preempt_curr()
Date: Thu, 25 Jun 2020 11:53:24 -0000 [thread overview]
Message-ID: <159308600431.16989.17842865258089428014.tip-bot2@tip-bot2> (raw)
In-Reply-To: <711a9c4b-ff32-1136-b848-17c622d548f3@yandex.ru>
The following commit has been merged into the sched/core branch of tip:
Commit-ID: aa93cd53bc1b91b5f99c7b55e3dcc1ac98e99558
Gitweb: https://git.kernel.org/tip/aa93cd53bc1b91b5f99c7b55e3dcc1ac98e99558
Author: Kirill Tkhai <tkhai@yandex.ru>
AuthorDate: Thu, 19 Dec 2019 16:44:55 -05:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 25 Jun 2020 13:45:44 +02:00
sched: Micro optimization in pick_next_task() and in check_preempt_curr()
This introduces an optimization based on xxx_sched_class addresses
in two hot scheduler functions: pick_next_task() and check_preempt_curr().
It is possible to compare pointers to sched classes to check, which
of them has a higher priority, instead of current iterations using
for_each_class().
One more result of the patch is that size of object file becomes a little
less (excluding added BUG_ON(), which goes in __init section):
$size kernel/sched/core.o
text data bss dec hex filename
before: 66446 18957 676 86079 1503f kernel/sched/core.o
after: 66398 18957 676 86031 1500f kernel/sched/core.o
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/711a9c4b-ff32-1136-b848-17c622d548f3@yandex.ru
---
kernel/sched/core.c | 19 ++++---------------
1 file changed, 4 insertions(+), 15 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 81640fe..0a08d0c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1412,20 +1412,10 @@ static inline void check_class_changed(struct rq *rq, struct task_struct *p,
void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
{
- const struct sched_class *class;
-
- if (p->sched_class == rq->curr->sched_class) {
+ if (p->sched_class == rq->curr->sched_class)
rq->curr->sched_class->check_preempt_curr(rq, p, flags);
- } else {
- for_each_class(class) {
- if (class == rq->curr->sched_class)
- break;
- if (class == p->sched_class) {
- resched_curr(rq);
- break;
- }
- }
- }
+ else if (p->sched_class > rq->curr->sched_class)
+ resched_curr(rq);
/*
* A queue event has occurred, and we're going to schedule. In
@@ -4003,8 +3993,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
* higher scheduling class, because otherwise those loose the
* opportunity to pull in more work from other CPUs.
*/
- if (likely((prev->sched_class == &idle_sched_class ||
- prev->sched_class == &fair_sched_class) &&
+ if (likely(prev->sched_class <= &fair_sched_class &&
rq->nr_running == rq->cfs.h_nr_running)) {
p = pick_next_task_fair(rq, prev, rf);
prev parent reply other threads:[~2020-06-25 11:54 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-19 16:35 [PATCH] sched: Force the address order of each sched class descriptor Steven Rostedt
2019-12-19 20:12 ` [PATCH v3] sched: Micro optimization in pick_next_task() and in check_preempt_curr() Kirill Tkhai
2019-12-19 21:04 ` Steven Rostedt
[not found] ` <711a9c4b-ff32-1136-b848-17c622d548f3@yandex.ru>
2019-12-20 9:26 ` [PATCH RESEND " Peter Zijlstra
2020-06-25 11:53 ` tip-bot2 for Kirill Tkhai [this message]
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