From: Hao Jia <jiahao.os@bytedance.com>
To: Benjamin Segall <bsegall@google.com>
Cc: mingo@redhat.com, peterz@infradead.org, mingo@kernel.org,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de,
bristot@redhat.com, vschneid@redhat.com,
mgorman@techsingularity.net, linux-kernel@vger.kernel.org
Subject: Re: [External] Re: [PATCH v4 4/4] sched/core: Avoid multiple calling update_rq_clock() in unthrottle_offline_cfs_rqs()
Date: Fri, 9 Jun 2023 11:19:03 +0800 [thread overview]
Message-ID: <504c702c-b31a-a9d4-22a0-8a09547d30e5@bytedance.com> (raw)
In-Reply-To: <xm26zg59acky.fsf@google.com>
On 2023/6/9 Benjamin Segall wrote:
> Hao Jia <jiahao.os@bytedance.com> writes:
>
>> This WARN_DOUBLE_CLOCK warning is triggered during cpu offline.
>> ------------[ cut here ]------------
>> rq->clock_update_flags & RQCF_UPDATED
>> WARNING: CPU: 0 PID: 3323 at kernel/sched/core.c:741
>> update_rq_clock+0xaf/0x180
>> Call Trace:
>> <TASK>
>> unthrottle_cfs_rq+0x4b/0x300
>> rq_offline_fair+0x89/0x90
>> set_rq_offline.part.118+0x28/0x60
>> rq_attach_root+0xc4/0xd0
>> cpu_attach_domain+0x3dc/0x7f0
>> partition_sched_domains_locked+0x2a5/0x3c0
>> rebuild_sched_domains_locked+0x477/0x830
>> rebuild_sched_domains+0x1b/0x30
>> cpuset_hotplug_workfn+0x2ca/0xc90
>> ? balance_push+0x56/0xf0
>> ? _raw_spin_unlock+0x15/0x30
>> ? finish_task_switch+0x98/0x2f0
>> ? __switch_to+0x291/0x410
>> ? __schedule+0x65e/0x1310
>> process_one_work+0x1bc/0x3d0
>> worker_thread+0x4c/0x380
>> ? preempt_count_add+0x92/0xa0
>> ? rescuer_thread+0x310/0x310
>> kthread+0xe6/0x110
>> ? kthread_complete_and_exit+0x20/0x20
>> ret_from_fork+0x1f/0x30
>>
>> The rq clock has been updated before the set_rq_offline()
>> function runs, so we don't need to call update_rq_clock() in
>> unthrottle_offline_cfs_rqs().
>
> I don't think we do in the path from rq_attach_root (though that's easy
> enough to fix, of course).
>
Thanks for your review.
Now our fix method is that after applying patch1, we update the rq clock
before set_rq_offline(). Then use rq_clock_{start, stop}_loop_update to
avoid updating the rq clock multiple times in unthrottle_cfs_rq().
Do you have any better suggestions?
Thanks,
Hao
next prev parent reply other threads:[~2023-06-09 3:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-08 6:33 [PATCH v4 0/4] Fix some warnings about rq clock Hao Jia
2023-06-08 6:33 ` [PATCH v4 1/4] sched/core: Fixed missing rq clock update before calling set_rq_offline() Hao Jia
2023-06-08 6:33 ` [PATCH v4 2/4] sched/core: Avoid double calling update_rq_clock() in __balance_push_cpu_stop() Hao Jia
2023-06-08 6:33 ` [PATCH v4 3/4] sched/core: Avoid multiple calling update_rq_clock() in __cfsb_csd_unthrottle() Hao Jia
2023-06-08 6:33 ` [PATCH v4 4/4] sched/core: Avoid multiple calling update_rq_clock() in unthrottle_offline_cfs_rqs() Hao Jia
2023-06-08 21:06 ` Benjamin Segall
2023-06-09 3:19 ` Hao Jia [this message]
2023-06-09 20:11 ` [External] " Benjamin Segall
2023-06-12 2:40 ` Hao Jia
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