From: Don Hiatt <dhiatt@digitalocean.com>
To: Josh Don <joshdon@google.com>
Cc: Aubrey Li <aubrey.intel@gmail.com>,
Aubrey Li <aubrey.li@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Joel Fernandes <joel@joelfernandes.org>,
"Hyser,Chris" <chris.hyser@oracle.com>,
Ingo Molnar <mingo@kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Mel Gorman <mgorman@suse.de>,
linux-kernel <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 04/19] sched: Prepare for Core-wide rq->lock
Date: Thu, 29 Apr 2021 14:09:36 -0700 [thread overview]
Message-ID: <CAOY2WozkceZ+B+AGTVLJ1H-jZDAbr2c7ksjtgrnr7DQ8h5raAg@mail.gmail.com> (raw)
In-Reply-To: <CABk29Nt_xBaoawiyMv1RG+Yzg_a9w5RMc6Zy0ggmS5K-9LzrUA@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1288 bytes --]
On Thu, Apr 29, 2021 at 1:48 PM Josh Don <joshdon@google.com> wrote:
>
> On Wed, Apr 28, 2021 at 9:41 AM Don Hiatt <dhiatt@digitalocean.com> wrote:
> >
> > I'm still seeing hard lockups while repeatedly setting cookies on qemu
> > processes even with
> > the updated patch. If there is any debug you'd like me to turn on,
> > just let me know.
> >
> > Thanks!
> >
> > don
>
> Thanks for the added context on your repro configuration. In addition
> to the updated patch from earlier, could you try the modification to
> double_rq_lock() from
> https://lkml.kernel.org/r/CABk29NuS-B3n4sbmavo0NDA1OCCsz6Zf2VDjjFQvAxBMQoJ_Lg@mail.gmail.com
> ? I have a feeling this is what's causing your lockup.
>
> Best,
> Josh
Hi Josh,
I've been running Aubrey+Peter's patch (attached) for almost 5 hours
and haven't had a single issue. :)
I'm running a set-cookie script every 5 seconds on the two VMs (each
vm is running
'sysbench --threads=1 --time=0 cpu run' to generate some load in the vm) and
I'm running two of the same sysbench runs on the HV while setting cookies
every 5 seconds.
Unless I jinxed us it looks like a great fix. :)
Let me know if there is anything else you'd like me to try. I'm going
to leave the tests running
and see what happens. I update with what I find.
Thanks!
don
[-- Attachment #2: aubrey-cosched.diff --]
[-- Type: application/octet-stream, Size: 2320 bytes --]
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f732642e3e09..1d7bc87007cd 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -290,6 +290,10 @@ static void sched_core_assert_empty(void)
static void __sched_core_enable(void)
{
static_branch_enable(&__sched_core_enabled);
+ /*
+ * Ensure raw_spin_rq_*lock*() have completed before flipping.
+ */
+ synchronize_rcu();
__sched_core_flip(true);
sched_core_assert_empty();
}
@@ -449,16 +453,23 @@ void raw_spin_rq_lock_nested(struct rq *rq, int subclass)
{
raw_spinlock_t *lock;
+ /* Matches synchronize_sched() in __sched_core_enabled() */
+ preempt_disable();
if (sched_core_disabled()) {
raw_spin_lock_nested(&rq->__lock, subclass);
+ /* preempt-count *MUST* be > 1 */
+ preempt_enable_no_resched();
return;
}
for (;;) {
lock = __rq_lockp(rq);
raw_spin_lock_nested(lock, subclass);
- if (likely(lock == __rq_lockp(rq)))
+ if (likely(lock == __rq_lockp(rq))) {
+ /* preempt-count *MUST* be > 1 */
+ preempt_enable_no_resched();
return;
+ }
raw_spin_unlock(lock);
}
}
@@ -468,14 +479,21 @@ bool raw_spin_rq_trylock(struct rq *rq)
raw_spinlock_t *lock;
bool ret;
- if (sched_core_disabled())
- return raw_spin_trylock(&rq->__lock);
+ /* Matches synchronize_sched() in __sched_core_enabled() */
+ preempt_disable();
+ if (sched_core_disabled()) {
+ ret = raw_spin_trylock(&rq->__lock);
+ preempt_enable();
+ return ret;
+ }
for (;;) {
lock = __rq_lockp(rq);
ret = raw_spin_trylock(lock);
- if (!ret || (likely(lock == __rq_lockp(rq))))
+ if (!ret || (likely(lock == __rq_lockp(rq)))) {
+ preempt_enable();
return ret;
+ }
raw_spin_unlock(lock);
}
}
@@ -493,14 +511,17 @@ void double_rq_lock(struct rq *rq1, struct rq *rq2)
{
lockdep_assert_irqs_disabled();
- if (rq1->cpu > rq2->cpu)
- swap(rq1, rq2);
-
- raw_spin_rq_lock(rq1);
- if (__rq_lockp(rq1) == __rq_lockp(rq2))
- return;
-
- raw_spin_rq_lock_nested(rq2, SINGLE_DEPTH_NESTING);
+ if (__rq_lockp(rq1) == __rq_lockp(rq2)) {
+ raw_spin_rq_lock(rq1);
+ } else {
+ if (__rq_lockp(rq1) < __rq_lockp(rq2)) {
+ raw_spin_rq_lock(rq1);
+ raw_spin_rq_lock_nested(rq2, SINGLE_DEPTH_NESTING);
+ } else {
+ raw_spin_rq_lock(rq2);
+ raw_spin_rq_lock_nested(rq1, SINGLE_DEPTH_NESTING);
+ }
+ }
}
#endif
next prev parent reply other threads:[~2021-04-29 21:09 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-22 12:04 [PATCH 00/19] sched: Core Scheduling Peter Zijlstra
2021-04-22 12:05 ` [PATCH 01/19] sched/fair: Add a few assertions Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-05-13 8:56 ` Ning, Hongyu
2021-04-22 12:05 ` [PATCH 02/19] sched: Provide raw_spin_rq_*lock*() helpers Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 03/19] sched: Wrap rq::lock access Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 04/19] sched: Prepare for Core-wide rq->lock Peter Zijlstra
2021-04-24 1:22 ` Josh Don
2021-04-26 8:31 ` Peter Zijlstra
2021-04-26 22:21 ` Josh Don
2021-04-27 17:10 ` Don Hiatt
2021-04-27 23:35 ` Josh Don
2021-04-28 1:03 ` Aubrey Li
2021-04-28 6:05 ` Aubrey Li
2021-04-28 10:57 ` Aubrey Li
2021-04-28 16:41 ` Don Hiatt
2021-04-29 20:48 ` Josh Don
2021-04-29 21:09 ` Don Hiatt [this message]
2021-04-29 23:22 ` Josh Don
2021-04-30 16:18 ` Don Hiatt
2021-04-30 8:26 ` Aubrey Li
2021-04-28 16:04 ` Don Hiatt
2021-04-27 23:30 ` Josh Don
2021-04-28 9:13 ` Peter Zijlstra
2021-04-28 10:35 ` Aubrey Li
2021-04-28 11:03 ` Peter Zijlstra
2021-04-28 14:18 ` Paul E. McKenney
2021-04-29 20:11 ` Josh Don
2021-05-03 19:17 ` Peter Zijlstra
2021-04-28 7:13 ` Peter Zijlstra
2021-04-28 6:02 ` Aubrey Li
2021-04-29 8:03 ` Aubrey Li
2021-04-29 20:39 ` Josh Don
2021-04-30 8:20 ` Aubrey Li
2021-04-30 8:48 ` Josh Don
2021-04-30 14:15 ` Aubrey Li
2021-05-04 7:38 ` Peter Zijlstra
2021-05-05 16:20 ` Don Hiatt
2021-05-06 10:25 ` Peter Zijlstra
2021-05-07 9:50 ` [PATCH v2 " Peter Zijlstra
2021-05-08 8:07 ` Aubrey Li
2021-05-12 9:07 ` Peter Zijlstra
2021-04-22 12:05 ` [PATCH 05/19] sched: " Peter Zijlstra
2021-05-07 9:50 ` [PATCH v2 " Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 06/19] sched: Optimize rq_lockp() usage Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 07/19] sched: Allow sched_core_put() from atomic context Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 08/19] sched: Introduce sched_class::pick_task() Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 09/19] sched: Basic tracking of matching tasks Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 10/19] sched: Add core wide task selection and scheduling Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 11/19] sched/fair: Fix forced idle sibling starvation corner case Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Vineeth Pillai
2021-04-22 12:05 ` [PATCH 12/19] sched: Fix priority inversion of cookied task with sibling Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Joel Fernandes (Google)
2021-04-22 12:05 ` [PATCH 13/19] sched/fair: Snapshot the min_vruntime of CPUs on force idle Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Joel Fernandes (Google)
2021-04-22 12:05 ` [PATCH 14/19] sched: Trivial forced-newidle balancer Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 15/19] sched: Migration changes for core scheduling Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Aubrey Li
2021-04-22 12:05 ` [PATCH 16/19] sched: Trivial core scheduling cookie management Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 17/19] sched: Inherit task cookie on fork() Peter Zijlstra
2021-05-10 16:06 ` Joel Fernandes
2021-05-10 16:22 ` Chris Hyser
2021-05-10 20:47 ` Joel Fernandes
2021-05-10 21:38 ` Chris Hyser
2021-05-12 9:05 ` Peter Zijlstra
2021-05-12 20:20 ` Josh Don
2021-05-12 21:07 ` Don Hiatt
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 18/19] sched: prctl() core-scheduling interface Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Chris Hyser
2021-06-14 23:36 ` [PATCH 18/19] " Josh Don
2021-06-15 11:31 ` Joel Fernandes
2021-08-05 16:53 ` Eugene Syromiatnikov
2021-08-05 17:00 ` Peter Zijlstra
2021-08-17 15:15 ` Eugene Syromiatnikov
2021-08-17 15:52 ` Peter Zijlstra
2021-08-17 23:17 ` Eugene Syromiatnikov
2021-08-19 11:09 ` [PATCH] sched: Fix Core-wide rq->lock for uninitialized CPUs Peter Zijlstra
2021-08-19 15:50 ` Tao Zhou
2021-08-19 16:19 ` Eugene Syromiatnikov
2021-08-20 0:18 ` Josh Don
2021-08-20 10:02 ` Peter Zijlstra
2021-08-23 9:07 ` [tip: sched/urgent] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 19/19] kselftest: Add test for core sched prctl interface Peter Zijlstra
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Chris Hyser
2021-04-22 16:43 ` [PATCH 00/19] sched: Core Scheduling Don Hiatt
2021-04-22 17:29 ` Peter Zijlstra
2021-04-30 6:47 ` Ning, Hongyu
2021-05-06 10:29 ` Peter Zijlstra
2021-05-06 12:53 ` Ning, Hongyu
2021-05-07 18:02 ` Joel Fernandes
2021-05-10 16:16 ` Vincent Guittot
2021-05-11 7:00 ` Vincent Guittot
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