From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com, juri.lelli@redhat.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de
Cc: linux-kernel@vger.kernel.org, qperret@google.com,
valentin.schneider@arm.com, qais.yousef@arm.com,
ktkhai@virtuozzo.com, peterz@infradead.org
Subject: [PATCH 2/7] sched/fair: Better document newidle_balance()
Date: Fri, 08 Nov 2019 14:15:55 +0100 [thread overview]
Message-ID: <20191108131909.488364308@infradead.org> (raw)
In-Reply-To: <20191108131553.027892369@infradead.org>
Whilst chasing the pick_next_task() race, there was some confusion
about the newidle_balance() return values. Document them.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/sched/fair.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9920,6 +9920,11 @@ static inline void nohz_newidle_balance(
/*
* idle_balance is called by schedule() if this_cpu is about to become
* idle. Attempts to pull tasks from other CPUs.
+ *
+ * Returns:
+ * <0 - we released the lock and there are !fair tasks present
+ * 0 - failed, no new tasks
+ * >0 - success, new (fair) tasks present
*/
int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
{
next prev parent reply other threads:[~2019-11-08 13:21 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-08 13:15 [PATCH 0/7] scheduler patches Peter Zijlstra
2019-11-08 13:15 ` [PATCH 1/7] sched: Fix pick_next_task() vs change pattern race Peter Zijlstra
2019-11-08 14:28 ` Quentin Perret
2019-11-08 16:05 ` Valentin Schneider
2019-11-08 20:49 ` Peter Zijlstra
2019-11-08 17:03 ` Qais Yousef
2019-11-08 13:15 ` Peter Zijlstra [this message]
2019-11-11 9:32 ` [tip: sched/core] sched/fair: Better document newidle_balance() tip-bot2 for Peter Zijlstra
2019-11-08 13:15 ` [PATCH 3/7] sched: Make pick_next_task_idle() more consistent Peter Zijlstra
2019-11-11 9:32 ` [tip: sched/core] sched/core: " tip-bot2 for Peter Zijlstra
2019-11-08 13:15 ` [PATCH 4/7] sched: Optimize pick_next_task() Peter Zijlstra
2019-11-08 14:33 ` Quentin Perret
2019-11-08 16:46 ` Vincent Guittot
2019-11-08 20:46 ` Peter Zijlstra
2019-11-11 9:32 ` [tip: sched/core] sched/core: " tip-bot2 for Peter Zijlstra
2019-11-08 13:15 ` [PATCH 5/7] sched: Simplify sched_class::pick_next_task() Peter Zijlstra
2019-11-11 9:32 ` [tip: sched/core] sched/core: " tip-bot2 for Peter Zijlstra
2019-11-08 13:15 ` [PATCH 6/7] sched/fair: Use mul_u32_u32() Peter Zijlstra
2019-11-11 9:32 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2019-11-08 13:16 ` [PATCH 7/7] sched: Further clarify sched_class::set_next_task() Peter Zijlstra
2019-11-11 9:32 ` [tip: sched/core] sched/core: " tip-bot2 for Peter Zijlstra
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