Re: [PATCH 05/12] workqueue: don't wake up other workers in rescuer
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
>> ---
>> 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
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Re: [PATCH 05/12] workqueue: don't wake up other workers in rescuer
(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
> ---
> 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?
Thanks.
--
tejun
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Please read the FAQ at http://www.tux.org/lkml/
[PATCH 05/12] workqueue: don't wake up other workers in rescuer
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 --- 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); - spin_unlock_irq(&gcwq->lock); } -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
