From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org, Ray Jui <rjui@broadcom.com>
Subject: Re: [PATCH 05/12] workqueue: don't wake up other workers in rescuer
Date: Fri, 28 Sep 2012 18:18:27 +0800 [thread overview]
Message-ID: <50657973.8090401@cn.fujitsu.com> (raw)
In-Reply-To: <20120926183429.GF12544@google.com>
On 09/27/2012 02:34 AM, Tejun Heo wrote:
> (cc'ing Ray Jui)
>
> On Thu, Sep 27, 2012 at 01:20:36AM +0800, Lai Jiangshan wrote:
>> rescuer is NOT_RUNNING, so there is no sense when it wakes up other workers,
>> if there are available normal workers, they are already woken up when needed.
>>
>> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
>> ---
>> kernel/workqueue.c | 8 --------
>> 1 files changed, 0 insertions(+), 8 deletions(-)
>>
>> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
>> index c718b94..6c339bf 100644
>> --- a/kernel/workqueue.c
>> +++ b/kernel/workqueue.c
>> @@ -2438,14 +2438,6 @@ repeat:
>>
>> process_scheduled_works(rescuer);
>>
>> - /*
>> - * Leave this gcwq. If keep_working() is %true, notify a
>> - * regular worker; otherwise, we end up with 0 concurrency
>> - * and stalling the execution.
>> - */
>> - if (keep_working(pool))
>> - wake_up_worker(pool);
>> -
>
> This was added by 7576958a9d5a4a6 ("workqueue: wake up a worker when a
> rescuer is leaving a gcwq") to fix a bug reported by Ray Jui.
>
> http://thread.gmane.org/gmane.linux.kernel/1098131
>
> I'm fairly sure it was a valid bug report. I don't think the
> depletion comes from concurrency management. It's just the lack of
> chaining which could lead to stall. What am I missing here?
>
"http://thread.gmane.org/gmane.linux.kernel/1098131" does not find out the root cause.
I find out the root cause with hard searching from the code, I will describe it later.
Thanks,
Lai
next prev parent reply other threads:[~2012-09-28 10:16 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-26 17:20 [PATCH 00/12] workqueue: simple cleanups Lai Jiangshan
2012-09-26 17:20 ` [PATCH 01/12] workqueue: add WORKER_RESCUER Lai Jiangshan
2012-09-26 18:07 ` Tejun Heo
2012-09-28 10:11 ` Lai Jiangshan
2012-09-26 17:20 ` [PATCH 02/12] workqueue: disallow set_cpus_allowed_ptr() from work item Lai Jiangshan
2012-09-26 18:12 ` Tejun Heo
2012-09-26 17:20 ` [PATCH 03/12] workqueue: remove WORKER_PREP from rescuer Lai Jiangshan
2012-09-26 18:24 ` Tejun Heo
2012-09-28 10:04 ` Lai Jiangshan
2012-09-30 7:39 ` Tejun Heo
2012-09-26 17:20 ` [PATCH 04/12] workqueue: simplify is_chained_work() Lai Jiangshan
2012-09-26 18:28 ` Tejun Heo
2012-09-28 9:52 ` Lai Jiangshan
2012-09-30 7:32 ` Tejun Heo
2012-09-26 17:20 ` [PATCH 05/12] workqueue: don't wake up other workers in rescuer Lai Jiangshan
2012-09-26 18:34 ` Tejun Heo
2012-09-28 10:18 ` Lai Jiangshan [this message]
2012-09-26 17:20 ` [PATCH 06/12] workqueue: destroy_worker() can only destory idle worker not just created worker Lai Jiangshan
2012-09-26 18:35 ` Tejun Heo
2012-09-26 17:20 ` [PATCH 07/12] workqueue: remove WORKER_STARTED Lai Jiangshan
2012-09-26 18:36 ` Tejun Heo
2012-09-28 9:52 ` Lai Jiangshan
2012-09-26 17:20 ` [PATCH 08/12] workqueue: fix comments of insert_work() Lai Jiangshan
2012-09-26 17:20 ` [PATCH 09/12] workqueue: declare system_highpri_wq Lai Jiangshan
2012-09-26 17:20 ` [PATCH 10/12] cpu-hotplug.txt: fix comments of work_on_cpu() Lai Jiangshan
2012-09-26 17:20 ` [RFC PATCH 11/12] workqueue: add WQ_CPU_INTENSIVE to system_long_wq Lai Jiangshan
2012-09-26 18:38 ` Tejun Heo
2012-09-28 8:06 ` Lai Jiangshan
2012-09-30 7:22 ` Tejun Heo
2012-09-26 17:20 ` [PATCH 12/12] workqueue: avoid work_on_cpu() to interfere system_wq Lai Jiangshan
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