From: Tejun Heo <tj@kernel.org>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org, Naohiro.Aota@wdc.com, kernel-team@meta.com
Subject: Re: [PATCH 04/10] workqueue: Move nr_active handling into helpers
Date: Wed, 27 Dec 2023 05:06:48 +0900 [thread overview]
Message-ID: <ZYsyWIVDoSFj9_ii@mtj.duckdns.org> (raw)
In-Reply-To: <CAJhGHyC4Qj7t=Emd65556r_g0fUbf9LWEA-1OKuwaDFTz8O50g@mail.gmail.com>
On Tue, Dec 26, 2023 at 05:12:55PM +0800, Lai Jiangshan wrote:
> On Wed, Dec 20, 2023 at 3:25 PM Tejun Heo <tj@kernel.org> wrote:
>
> > +static bool pwq_tryinc_nr_active(struct pool_workqueue *pwq)
> > {
> > - struct work_struct *work = list_first_entry(&pwq->inactive_works,
> > - struct work_struct, entry);
> > + struct workqueue_struct *wq = pwq->wq;
> > + struct worker_pool *pool = pwq->pool;
> > + bool obtained;
> >
> > - pwq_activate_work(pwq, work);
> > + lockdep_assert_held(&pool->lock);
> > +
> > + obtained = pwq->nr_active < wq->max_active;
>
> It is better to use READ_ONCE(wq->max_active) here in case
> the compiler issues code to calculate "obtained" multi-time.
>
> Theoretically, READ_ONCE(wq->max_active) is recommended
> from the patch1 in pwq_dec_nr_in_flight() and __queue_work()
> since there is no wq->mutex for them.
Yeah, good point. Lemme add WRITE/READ_ONCE() around max_active accesses.
Thanks.
--
tejun
next prev parent reply other threads:[~2023-12-26 20:06 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-20 7:24 [PATCHSET wq/for-6.8] workqueue: Implement system-wide max_active for unbound workqueues Tejun Heo
2023-12-20 7:24 ` [PATCH 01/10] workqueue: Move pwq->max_active to wq->max_active Tejun Heo
2023-12-26 9:13 ` Lai Jiangshan
2023-12-26 20:05 ` Tejun Heo
2023-12-26 21:36 ` Tejun Heo
2023-12-20 7:24 ` [PATCH 02/10] workqueue: Factor out pwq_is_empty() Tejun Heo
2023-12-20 7:24 ` [PATCH 03/10] workqueue: Replace pwq_activate_inactive_work() with [__]pwq_activate_work() Tejun Heo
2023-12-20 7:24 ` [PATCH 04/10] workqueue: Move nr_active handling into helpers Tejun Heo
2023-12-26 9:12 ` Lai Jiangshan
2023-12-26 20:06 ` Tejun Heo [this message]
2023-12-20 7:24 ` [PATCH 05/10] workqueue: Make wq_adjust_max_active() round-robin pwqs while activating Tejun Heo
2023-12-20 7:24 ` [PATCH 06/10] workqueue: Add first_possible_node and node_nr_cpus[] Tejun Heo
2023-12-20 7:24 ` [PATCH 07/10] workqueue: Move pwq_dec_nr_in_flight() to the end of work item handling Tejun Heo
2023-12-20 7:24 ` [PATCH 08/10] workqueue: Introduce struct wq_node_nr_active Tejun Heo
2023-12-26 9:14 ` Lai Jiangshan
2023-12-26 20:12 ` Tejun Heo
2023-12-20 7:24 ` [PATCH 09/10] workqueue: Implement system-wide nr_active enforcement for unbound workqueues Tejun Heo
2023-12-20 7:24 ` [PATCH 10/10] workqueue: Reimplement ordered workqueue using shared nr_active Tejun Heo
2024-01-13 0:18 ` Tejun Heo
2023-12-20 9:20 ` [PATCHSET wq/for-6.8] workqueue: Implement system-wide max_active for unbound workqueues Lai Jiangshan
2023-12-21 23:01 ` Tejun Heo
2023-12-22 8:04 ` Lai Jiangshan
2023-12-22 9:08 ` Tejun Heo
2024-01-05 2:44 ` Naohiro Aota
2024-01-12 0:49 ` Tejun Heo
2024-01-13 0:17 ` Tejun Heo
2024-01-15 5:46 ` Naohiro Aota
2024-01-16 21:04 ` Tejun Heo
2024-01-30 2:24 ` Naohiro Aota
2024-01-30 16:11 ` Tejun Heo
-- strict thread matches above, loose matches on Subject: below --
2024-01-25 17:05 [PATCHSET v3 wq/for-6.9] " Tejun Heo
2024-01-25 17:05 ` [PATCH 04/10] workqueue: Move nr_active handling into helpers Tejun Heo
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