>> 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();
--
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/

Reply via email to