From: Andrew Morton <akpm@linux-foundation.org>
To: Michel Lespinasse <walken@google.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Nick Piggin <npiggin@kernel.dk>, Rik van Riel <riel@redhat.com>
Subject: Re: [RFC] mlock: release mmap_sem every 256 faulted pages
Date: Mon, 22 Nov 2010 21:57:46 -0800 [thread overview]
Message-ID: <20101122215746.e847742d.akpm@linux-foundation.org> (raw)
In-Reply-To: <20101123050052.GA24039@google.com>
On Mon, 22 Nov 2010 21:00:52 -0800 Michel Lespinasse <walken@google.com> wrote:
> Hi,
>
> I'd like to sollicit comments on this proposal:
>
> Currently mlock() holds mmap_sem in exclusive mode while the pages get
> faulted in. In the case of a large mlock, this can potentially take a
> very long time.
A more compelling description of why this problem needs addressing
would help things along.
> + /*
> + * Limit batch size to 256 pages in order to reduce
> + * mmap_sem hold time.
> + */
> + nfault = nstart + 256 * PAGE_SIZE;
It would be nicer if there was an rwsem API to ask if anyone is
currently blocked in down_read() or down_write(). That wouldn't be too
hard to do. It wouldn't detect people polling down_read_trylock() or
down_write_trylock() though.
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next prev parent reply other threads:[~2010-11-23 6:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-23 5:00 [RFC] mlock: release mmap_sem every 256 faulted pages Michel Lespinasse
2010-11-23 5:57 ` Andrew Morton [this message]
2010-11-23 7:49 ` KOSAKI Motohiro
2010-11-23 20:55 ` Michel Lespinasse
2010-11-23 23:57 ` KOSAKI Motohiro
2010-12-01 0:14 ` KOSAKI Motohiro
2010-12-01 4:42 ` KOSAKI Motohiro
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