Hello,
On Tue, Aug 14, 2012 at 02:43:28AM +0900, JoonSoo Kim wrote:
> >> And, do u mean @cpu is WORK_CPU_UNBOUND?
> >
> > @cpu could be WORK_CPU_UNBOUND at that point. The timer will be added
> > to local CPU but @work->data would be pointing to WORK_CPU_UNBOUND,
> > again triggering the condition. Given that @cpu being
> > WORK_CPU_UNBOUND is far more common than an actual CPU number, the
> > patch would actually increase spurious nrt lookups. The right thing
> > to do is probably setting cpu to raw_smp_processor_id() beforehand.
>
> I got your point.
> Thanks for kind illustration.
>
> Following is a alternative implementation for this.
> I thinks this is too rare case, so it doesn't help in any real workload.
> But how do you thinks?
>
> @@ -1156,7 +1156,9 @@ int queue_delayed_work_on(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)
> + if (!gcwq)
> + lcpu = cpu;
> + else if (gcwq->cpu != WORK_CPU_UNBOUND)
> lcpu = gcwq->cpu;
> else
> lcpu = raw_smp_processor_id();
Why not just do
if (cpu == WORK_CPU_UNBOUND)
cpu = raw_smp_processor_id();
if (!(wq->flags...) {
...
if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND)
lcpu = gcwq->cpu;
else
lcpu = cpu;
}
...
add_timer_on(timer, cpu);
Also, can you please base the patches on top of the following git
branch?
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git for-3.7
Thanks.
--
tejun
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