linux-kernel - Re: [PATCH v4 3/3] [Doc] Workqueue: add WQ

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Message-ID: <CAAofZF4TeyK=Kbmtb=GbMhYGc4XTJh1TdQ5Jr2+tgdOh-rCXhg@mail.gmail.com>
Date: Fri, 13 Jun 2025 15:23:34 +0200
From: Marco Crivellari <marco.crivellari@...e.com>
To: Frederic Weisbecker <frederic@...nel.org>
Cc: linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>, 
	Lai Jiangshan <jiangshanlai@...il.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH v4 3/3] [Doc] Workqueue: add WQ_PERCPU

Thank you!

> But since the support for this is not there yet, perhaps this note
> should be added later? Ie: if someone omits the WQ_UNBOUND flag currently,
> the workqueue will be percpu.

Yes, it makes sense.

I will send the v5 with all the corrections.

Thanks.

On Fri, Jun 13, 2025 at 3:13 PM Frederic Weisbecker <frederic@...nel.org> wrote:
>
> Le Thu, Jun 12, 2025 at 03:33:35PM +0200, Marco Crivellari a écrit :
> > Workqueue documentation upgraded with the description
> > of the new added flag, WQ_PERCPU.
> >
> > Also the WQ_UNBOUND flag documentation has been integrated
> >
> > Suggested-by: Tejun Heo <tj@...nel.org>
> > Signed-off-by: Marco Crivellari <marco.crivellari@...e.com>
>
> Thanks, a few spelling nits below:
>
> > ---
> >  Documentation/core-api/workqueue.rst | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/Documentation/core-api/workqueue.rst b/Documentation/core-api/workqueue.rst
> > index e295835fc116..ae63a648a51b 100644
> > --- a/Documentation/core-api/workqueue.rst
> > +++ b/Documentation/core-api/workqueue.rst
> > @@ -183,6 +183,12 @@ resources, scheduled and executed.
> >    BH work items cannot sleep. All other features such as delayed queueing,
> >    flushing and canceling are supported.
> >
> > +``WQ_PERCPU``
> > +  Work items queued to a per-cpu wq are bound to that specific CPU.
>
> s/that/a
>
> > +  This flag it's the right choice when cpu locality is important.
>
> s/it's/is
>
> > +
> > +  This flag is the complement of ``WQ_UNBOUND``.
> > +
> >  ``WQ_UNBOUND``
> >    Work items queued to an unbound wq are served by the special
> >    worker-pools which host workers which are not bound to any
> > @@ -200,6 +206,10 @@ resources, scheduled and executed.
> >    * Long running CPU intensive workloads which can be better
> >      managed by the system scheduler.
> >
> > +  **Note:** This flag will be removed in future and all the work
>
> in the future
>
> > +  items that dosen't need to be bound to a specific CPU, should not
>
> s/dosen't/don't
>
> > +  use this flags.
>
> flag.
>
> But since the support for this is not there yet, perhaps this note
> should be added later? Ie: if someone omits the WQ_UNBOUND flag currently,
> the workqueue will be percpu.
>
> Thanks.
>
> > +
> >  ``WQ_FREEZABLE``
> >    A freezable wq participates in the freeze phase of the system
> >    suspend operations.  Work items on the wq are drained and no
> > --
> > 2.49.0
> >
>
> --
> Frederic Weisbecker
> SUSE Labs



-- 

Marco Crivellari

L3 Support Engineer, Technology & Product




marco.crivellari@...e.com