linux-kernel - Re: [PATCH 1/6] mlock: only hold mmap_sem in shared mode when faulting in pages

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Message-ID: <AANLkTim-CBKeXYiK=TWHafcEto32mKAqCggTVW5-r9nj@mail.gmail.com>
Date:	Tue, 14 Dec 2010 15:22:35 -0800
From:	Michel Lespinasse <walken@...gle.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Hugh Dickins <hughd@...gle.com>,
	Rik van Riel <riel@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Nick Piggin <npiggin@...nel.dk>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/6] mlock: only hold mmap_sem in shared mode when
 faulting in pages

On Tue, Dec 14, 2010 at 7:43 AM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> Without _any_ at all of the crappy "rwsem_contended()" or the stupid
> constants, we hold it only for reading, _and_ we drop it for any
> actual IO. So the semaphore is held only for actual CPU intensive
> cases. We're talking a reduction from minutes to milliseconds.

It's actually still several seconds for a large enough mlock from page cache.

But yes, I agree it'll do fine for now :)

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
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