Messages in this thread | | | Date | Tue, 14 Aug 2012 12:00:20 -0700 | From | Tejun Heo <> | Subject | Re: [PATCH v2 3/6] workqueue: change value of lcpu in __queue_delayed_work_on() |
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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 <js1304@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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