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From: Andrew Morton <akpm@osdl.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	linux-mm@kvack.org,
	Linux Kernel list <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@osdl.org>,
	Mike Waychison <mikew@google.com>
Subject: Re: [RFC] page fault retry with NOPAGE_RETRY
Date: Fri, 15 Sep 2006 00:35:29 -0700	[thread overview]
Message-ID: <20060915003529.8a59c542.akpm@osdl.org> (raw)
In-Reply-To: <20060915001151.75f9a71b.akpm@osdl.org>

On Fri, 15 Sep 2006 00:11:51 -0700
Andrew Morton <akpm@osdl.org> wrote:

> b) It could be more efficient.  Most of the time, there's no need to
>    back all the way out of the pagefault handler and rerun the whole thing.
>    Because most of the time, nobody changed anything in the mm_struct.  We
>    _could_ just retake the mmap_sem after the page comes uptodate and, if
>    nothing has changed, proceed.  I see two ways of doing this:
> 
>    - The simple way: look to see if any other processes are sharing
>      this mm_struct.  If not, just do the synchronous read inside mmap_sem.

This assumes that no other heavyweight process will try to modify this
single-threaded process's mm.  I don't _think_ that happens anywhere, does
it?  access_process_vm() is the only case I can think of, and it does
down_read(other process's mmap_sem).

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  reply	other threads:[~2006-09-15  7:35 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-09-14 22:55 [RFC] page fault retry with NOPAGE_RETRY Benjamin Herrenschmidt
2006-09-15  0:19 ` Linus Torvalds
2006-09-15  7:11 ` Andrew Morton
2006-09-15  7:35   ` Andrew Morton [this message]
2006-09-15 13:30     ` Hugh Dickins
2006-09-16  1:03       ` Benjamin Herrenschmidt
2006-09-19 23:35   ` Mike Waychison
2006-09-19 23:50     ` Benjamin Herrenschmidt
2006-09-19 23:59       ` Andrew Morton
2006-09-20  0:06         ` Benjamin Herrenschmidt
2006-09-20  0:05       ` Benjamin Herrenschmidt
2006-09-20  0:21         ` Andrew Morton
2006-09-20  1:57           ` Benjamin Herrenschmidt
2006-09-20  3:05             ` Andrew Morton
2006-09-20  5:04               ` Benjamin Herrenschmidt
2006-09-20  5:26                 ` Andrew Morton
2006-09-20  6:54                   ` Benjamin Herrenschmidt
2006-09-20 17:53                     ` Andrew Morton
2006-09-21 22:05                       ` Benjamin Herrenschmidt
2006-09-21 22:41                         ` Andrew Morton
2006-09-21 23:09                           ` Benjamin Herrenschmidt
2006-09-23 14:21                       ` Hugh Dickins
2006-09-23 19:46                         ` Andrew Morton
2006-09-23 22:35                           ` Benjamin Herrenschmidt
2006-09-20  5:06               ` Benjamin Herrenschmidt
2006-09-20  1:14       ` Mike Waychison
2006-09-20  2:02         ` Benjamin Herrenschmidt
2006-09-15 21:35 ` Arnd Bergmann

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