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SubjectRe: [PATCH 2/5] workqueue: change value of lcpu in queue_delayed_work_on()
From
>> 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();

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