From: Michal Hocko <mhocko@suse.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Christoph Lameter <cl@linux.com>,
Aaron Tomlin <atomlin@atomlin.com>,
Frederic Weisbecker <frederic@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Vlastimil Babka <vbabka@suse.cz>, Tejun Heo <tj@kernel.org>,
Lai Jiangshan <jiangshanlai@gmail.com>
Subject: Re: [PATCH 3/4] workqueue: add schedule_on_each_cpumask helper
Date: Mon, 5 Jun 2023 09:12:19 +0200 [thread overview]
Message-ID: <ZH2K0wdL3YAOUaTf@dhcp22.suse.cz> (raw)
In-Reply-To: <ZHohHHvtDjIJHA+a@tpad>
On Fri 02-06-23 14:04:28, Marcelo Tosatti wrote:
> On Fri, Jun 02, 2023 at 12:48:23PM +0200, Michal Hocko wrote:
[...]
> > > + if (!alloc_cpumask_var(&effmask, GFP_KERNEL)) {
> > > + free_percpu(works);
> > > + return -ENOMEM;
> > > + }
> > > +
> > > + cpumask_and(effmask, cpumask, cpu_online_mask);
> > > +
> > > + cpus_read_lock();
> > > +
> > > + for_each_cpu(cpu, effmask) {
> >
> > Is the cpu_online_mask dance really necessary?
>
> > Why cannot you simply do for_each_online_cpu here?
>
> Are you suggesting to do:
>
> for_each_online_cpu(cpu) {
> if cpu is not in cpumask
> continue;
> ...
> }
>
> This does not seem efficient.
Are you sure this is less sufficient than a memory allocation?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2023-06-05 7:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-30 14:52 [PATCH 0/4] vmstat bug fixes for nohz_full CPUs Marcelo Tosatti
2023-05-30 14:52 ` [PATCH 1/4] vmstat: allow_direct_reclaim should use zone_page_state_snapshot Marcelo Tosatti
2023-06-02 10:53 ` Michal Hocko
2023-05-30 14:52 ` [PATCH 2/4] vmstat: skip periodic vmstat update for nohz full CPUs Marcelo Tosatti
2023-06-02 10:39 ` Michal Hocko
2023-06-02 16:57 ` Marcelo Tosatti
2023-05-30 14:52 ` [PATCH 3/4] workqueue: add schedule_on_each_cpumask helper Marcelo Tosatti
2023-05-30 20:09 ` Andrew Morton
2023-06-01 18:13 ` Marcelo Tosatti
2023-06-02 10:48 ` Michal Hocko
2023-06-02 17:04 ` Marcelo Tosatti
2023-06-05 7:12 ` Michal Hocko [this message]
2023-05-30 14:52 ` [PATCH 4/4] mm/vmstat: do not refresh stats for nohz_full CPUs Marcelo Tosatti
2023-06-02 10:50 ` Michal Hocko
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