From: Tejun Heo <tj@kernel.org>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Hillf Danton <hillf.zj@alibaba-inc.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Petr Mladek <pmladek@suse.cz>
Subject: Re: [PATCH 3/4] mm, page_alloc: Drain per-cpu pages from workqueue context
Date: Mon, 23 Jan 2017 12:03:29 -0500 [thread overview]
Message-ID: <20170123170329.GA7820@htj.duckdns.org> (raw)
In-Reply-To: <20170120152606.w3hb53m2w6thzsqq@techsingularity.net>
Hello,
On Fri, Jan 20, 2017 at 03:26:06PM +0000, Mel Gorman wrote:
> > This translates to queue_work_on(), which has the comment of "We queue
> > the work to a specific CPU, the caller must ensure it can't go away.",
> > so is this safe? lru_add_drain_all() uses get_online_cpus() around this.
> >
>
> get_online_cpus() would be required.
This part of workqueue usage has always been a bit clunky and I should
imrpove it but you don't necessarily have to pin the cpus from
queueing to execution. You can queue without checking whether the CPU
is online and instead synchronize the actual work item execution
against cpu offline callback so that if the work item gets executed
after offline callback is finished, it becomes a noop.
Thanks.
--
tejun
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next prev parent reply other threads:[~2017-01-23 17:03 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-17 9:29 [PATCH 0/4] Use per-cpu allocator for !irq requests and prepare for a bulk allocator v4 Mel Gorman
2017-01-17 9:29 ` [PATCH 1/4] mm, page_alloc: Split buffered_rmqueue Mel Gorman
2017-01-17 18:07 ` Jesper Dangaard Brouer
2017-01-17 18:17 ` Vlastimil Babka
2017-01-17 20:20 ` Mel Gorman
2017-01-17 21:07 ` Mel Gorman
2017-01-17 21:24 ` Vlastimil Babka
2017-01-17 9:29 ` [PATCH 2/4] mm, page_alloc: Split alloc_pages_nodemask Mel Gorman
2017-01-17 9:29 ` [PATCH 3/4] mm, page_alloc: Drain per-cpu pages from workqueue context Mel Gorman
2017-01-20 14:26 ` Vlastimil Babka
2017-01-20 15:26 ` Mel Gorman
2017-01-23 16:29 ` Petr Mladek
2017-01-23 16:50 ` Mel Gorman
2017-01-23 17:03 ` Tejun Heo [this message]
2017-01-23 20:04 ` Mel Gorman
2017-01-23 20:55 ` Tejun Heo
2017-01-23 23:04 ` Mel Gorman
2017-01-24 16:07 ` Tejun Heo
2017-01-24 23:54 ` Mel Gorman
2017-01-25 2:02 ` Tejun Heo
2017-01-25 8:30 ` Mel Gorman
2017-01-24 11:08 ` Vlastimil Babka
2017-01-17 9:29 ` [PATCH 4/4] mm, page_alloc: Only use per-cpu allocator for irq-safe requests Mel Gorman
2017-01-20 15:02 ` Vlastimil Babka
2017-01-23 11:17 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2017-01-23 15:39 [PATCH 0/4] Use per-cpu allocator for !irq requests and prepare for a bulk allocator v5 Mel Gorman
2017-01-23 15:39 ` [PATCH 3/4] mm, page_alloc: Drain per-cpu pages from workqueue context Mel Gorman
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