* Re: [RFC 1/4] workqueue: fix selecting cpu for queuing work
[not found] ` <20191211105919.10652-1-hdanton@sina.com>
@ 2019-12-11 23:07 ` Daniel Jordan
2020-01-23 22:37 ` Daniel Jordan
0 siblings, 1 reply; 3+ messages in thread
From: Daniel Jordan @ 2019-12-11 23:07 UTC (permalink / raw)
To: Hillf Danton; +Cc: linux-kernel, linux-mm, Tejun Heo, Lai Jiangshan
[please cc maintainers]
On Wed, Dec 11, 2019 at 06:59:19PM +0800, Hillf Danton wrote:
> Round robin is needed only for unbound workqueue and wq_unbound_cpumask
> has nothing to do with standard workqueues, so we have to select cpu in
> case of WORK_CPU_UNBOUND also with workqueue type taken into account.
Good catch. I'd include something like this in the changelog.
Otherwise, work queued on a bound workqueue with WORK_CPU_UNBOUND might
not prefer the local CPU if wq_unbound_cpumask is non-empty and doesn't
include that CPU.
With that you can add
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC 3/4] workqueue: reap dead pool workqueue on queuing work
[not found] ` <20191211112229.22652-1-hdanton@sina.com>
@ 2019-12-11 23:25 ` Daniel Jordan
0 siblings, 0 replies; 3+ messages in thread
From: Daniel Jordan @ 2019-12-11 23:25 UTC (permalink / raw)
To: Hillf Danton; +Cc: linux-kernel, linux-mm, Tejun Heo, Lai Jiangshan
On Wed, Dec 11, 2019 at 07:22:29PM +0800, Hillf Danton wrote:
> Release rcu lock to reap dead pool workqueue.
What's to be gained by reaping the pwq (and possibly worker pool and wq) before
__queue_work() retries? It'll just happen after the queueing finishes.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC 1/4] workqueue: fix selecting cpu for queuing work
2019-12-11 23:07 ` [RFC 1/4] workqueue: fix selecting cpu for queuing work Daniel Jordan
@ 2020-01-23 22:37 ` Daniel Jordan
0 siblings, 0 replies; 3+ messages in thread
From: Daniel Jordan @ 2020-01-23 22:37 UTC (permalink / raw)
To: Hillf Danton; +Cc: linux-kernel, linux-mm, Tejun Heo, Lai Jiangshan
On Wed, Dec 11, 2019 at 06:07:35PM -0500, Daniel Jordan wrote:
> [please cc maintainers]
>
> On Wed, Dec 11, 2019 at 06:59:19PM +0800, Hillf Danton wrote:
> > Round robin is needed only for unbound workqueue and wq_unbound_cpumask
> > has nothing to do with standard workqueues, so we have to select cpu in
> > case of WORK_CPU_UNBOUND also with workqueue type taken into account.
>
> Good catch. I'd include something like this in the changelog.
>
> Otherwise, work queued on a bound workqueue with WORK_CPU_UNBOUND might
> not prefer the local CPU if wq_unbound_cpumask is non-empty and doesn't
> include that CPU.
>
> With that you can add
>
> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Any plans to repost this patch, Hillf? If not, I can do it while retaining
your authorship.
Adding back the context, which I forgot to keep when adding the maintainers.
> > Fixes: ef557180447f ("workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs")
> > Signed-off-by: Hillf Danton <hdanton@sina.com>
> > ---
> >
> > --- a/kernel/workqueue.c
> > +++ c/kernel/workqueue.c
> > @@ -1409,16 +1409,19 @@ static void __queue_work(int cpu, struct
> > if (unlikely(wq->flags & __WQ_DRAINING) &&
> > WARN_ON_ONCE(!is_chained_work(wq)))
> > return;
> > +
> > rcu_read_lock();
> > retry:
> > - if (req_cpu == WORK_CPU_UNBOUND)
> > - cpu = wq_select_unbound_cpu(raw_smp_processor_id());
> > -
> > /* pwq which will be used unless @work is executing elsewhere */
> > - if (!(wq->flags & WQ_UNBOUND))
> > - pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
> > - else
> > + if (wq->flags & WQ_UNBOUND) {
> > + if (req_cpu == WORK_CPU_UNBOUND)
> > + cpu = wq_select_unbound_cpu(raw_smp_processor_id());
> > pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
> > + } else {
> > + if (req_cpu == WORK_CPU_UNBOUND)
> > + cpu = raw_smp_processor_id();
> > + pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
> > + }
> >
> > /*
> > * If @work was previously on a different pool, it might still be
> >
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] ` <20191211105919.10652-1-hdanton@sina.com>
2019-12-11 23:07 ` [RFC 1/4] workqueue: fix selecting cpu for queuing work Daniel Jordan
2020-01-23 22:37 ` Daniel Jordan
[not found] ` <20191211112229.22652-1-hdanton@sina.com>
2019-12-11 23:25 ` [RFC 3/4] workqueue: reap dead pool workqueue on " Daniel Jordan
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