From: tip-bot for Davidlohr Bueso <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: matt@codeblueprint.co.uk, dbueso@suse.de, mingo@kernel.org,
linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
peterz@infradead.org, efault@gmx.de, dave@stgolabs.net,
tglx@linutronix.de, hpa@zytor.com
Subject: [tip:sched/urgent] sched/rt: Fix rq->clock_update_flags < RQCF_ACT_SKIP warning
Date: Thu, 5 Apr 2018 02:16:58 -0700 [thread overview]
Message-ID: <tip-d29a20645d5e929aa7e8616f28e5d8e1c49263ec@git.kernel.org> (raw)
In-Reply-To: <20180402164954.16255-1-dave@stgolabs.net>
Commit-ID: d29a20645d5e929aa7e8616f28e5d8e1c49263ec
Gitweb: https://git.kernel.org/tip/d29a20645d5e929aa7e8616f28e5d8e1c49263ec
Author: Davidlohr Bueso <dave@stgolabs.net>
AuthorDate: Mon, 2 Apr 2018 09:49:54 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 5 Apr 2018 09:20:46 +0200
sched/rt: Fix rq->clock_update_flags < RQCF_ACT_SKIP warning
While running rt-tests' pi_stress program I got the following splat:
rq->clock_update_flags < RQCF_ACT_SKIP
WARNING: CPU: 27 PID: 0 at kernel/sched/sched.h:960 assert_clock_updated.isra.38.part.39+0x13/0x20
[...]
<IRQ>
enqueue_top_rt_rq+0xf4/0x150
? cpufreq_dbs_governor_start+0x170/0x170
sched_rt_rq_enqueue+0x65/0x80
sched_rt_period_timer+0x156/0x360
? sched_rt_rq_enqueue+0x80/0x80
__hrtimer_run_queues+0xfa/0x260
hrtimer_interrupt+0xcb/0x220
smp_apic_timer_interrupt+0x62/0x120
apic_timer_interrupt+0xf/0x20
</IRQ>
[...]
do_idle+0x183/0x1e0
cpu_startup_entry+0x5f/0x70
start_secondary+0x192/0x1d0
secondary_startup_64+0xa5/0xb0
We can get rid of it be the "traditional" means of adding an
update_rq_clock() call after acquiring the rq->lock in
do_sched_rt_period_timer().
The case for the RT task throttling (which this workload also hits)
can be ignored in that the skip_update call is actually bogus and
quite the contrary (the request bits are removed/reverted).
By setting RQCF_UPDATED we really don't care if the skip is happening
or not and will therefore make the assert_clock_updated() check happy.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: linux-kernel@vger.kernel.org
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20180402164954.16255-1-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/rt.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 86b77987435e..ad13e6242481 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -839,6 +839,8 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
continue;
raw_spin_lock(&rq->lock);
+ update_rq_clock(rq);
+
if (rt_rq->rt_time) {
u64 runtime;
prev parent reply other threads:[~2018-04-05 9:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-02 16:49 [PATCH] sched/rt: Fix rq->clock_update_flags < RQCF_ACT_SKIP warning Davidlohr Bueso
2018-04-03 12:39 ` Matt Fleming
2018-04-04 15:27 ` Peter Zijlstra
2018-04-04 16:15 ` Davidlohr Bueso
2018-04-04 16:39 ` Peter Zijlstra
2018-04-05 7:21 ` Ingo Molnar
2018-04-05 9:17 ` [tip:sched/urgent] sched/core: Simplify helpers for rq clock update skip requests tip-bot for Davidlohr Bueso
2018-04-05 9:16 ` tip-bot for Davidlohr Bueso [this message]
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