On Wed, Aug 15, 2012 at 03:10:13AM +0900, Joonsoo Kim wrote:
> We assign cpu id into work struct's data field in __queue_delayed_work_on().
> In current implementation, when work is come in first time,
> current running cpu id is assigned.
> If we do __queue_delayed_work_on() with CPU A on CPU B,
> __queue_work() invoked in delayed_work_timer_fn() go into
> the following sub-optimal path in case of WQ_NON_REENTRANT.
>
> gcwq = get_gcwq(cpu);
> if (wq->flags & WQ_NON_REENTRANT &&
> (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) {
>
> Change lcpu to @cpu and rechange lcpu to local cpu if lcpu is
> WORK_CPU_UNBOUND.
> It is sufficient to prevent to go into sub-optimal path.
>
> Signed-off-by: Joonsoo Kim <js1...@gmail.com>
>
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 6a17ab0..f55ac26 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -1358,9 +1358,10 @@ static void __queue_delayed_work(int cpu, struct
> workqueue_struct *wq,
> if (!(wq->flags & WQ_UNBOUND)) {
> struct global_cwq *gcwq = get_work_gcwq(work);
>
> - if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND)
> + lcpu = cpu;
> + if (gcwq)
> lcpu = gcwq->cpu;
> - else
> + if (lcpu == WORK_CPU_UNBOUND)
> lcpu = raw_smp_processor_id();
Can you please add a comment explanining what's going on?
--
tejun
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