From: Michel Lespinasse <walken@google.com>
To: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Ying Han <yinghan@google.com>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Nick Piggin <npiggin@kernel.dk>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 2/3] Retry page fault when blocking on disk transfer.
Date: Tue, 5 Oct 2010 15:44:22 -0700 [thread overview]
Message-ID: <AANLkTimdACZ9Xm01DM2+E64+T5XfLffrkFBhf7CJ286p@mail.gmail.com> (raw)
In-Reply-To: <4CAB628D.3030205@redhat.com>
On Tue, Oct 5, 2010 at 10:38 AM, Rik van Riel <riel@redhat.com> wrote:
> On 10/05/2010 03:53 AM, Michel Lespinasse wrote:
>>
>> This change reduces mmap_sem hold times that are caused by waiting for
>> disk transfers when accessing file mapped VMAs. It introduces the
>> VM_FAULT_ALLOW_RETRY flag, which indicates that the call site wants
>> mmap_sem to be released if blocking on a pending disk transfer.
>> In that case, filemap_fault() returns the VM_FAULT_RETRY status bit
>> and do_page_fault() will then re-acquire mmap_sem and retry the page
>> fault.
>> It is expected that the retry will hit the same page which will now be
>> cached, and thus it will complete with a low mmap_sem hold time.
>>
>> Signed-off-by: Michel Lespinasse<walken@google.com>
>
> Acked-by: Rik van Riel <riel@redhat.com>
>
> Looks like it should be relatively easy to do something
> similar in do_swap_page also.
Good idea. We don't make use of swap too much, which is probably why
we didn't have that in our kernel, but it seems like a good idea just
for uniformity. I'll add this in a follow-on patch.
--
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
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next prev parent reply other threads:[~2010-10-05 22:44 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-05 7:53 [PATCH 0/3] V2: Reduce mmap_sem hold times during file backed page faults Michel Lespinasse
2010-10-05 7:53 ` [PATCH 1/3] filemap_fault: unique path for locking page Michel Lespinasse
2010-10-05 17:07 ` Rik van Riel
2010-10-05 7:53 ` [PATCH 2/3] Retry page fault when blocking on disk transfer Michel Lespinasse
2010-10-05 17:33 ` Linus Torvalds
2010-10-05 17:38 ` Rik van Riel
2010-10-05 22:44 ` Michel Lespinasse [this message]
2010-10-08 4:39 ` Michel Lespinasse
2010-10-08 13:24 ` Rik van Riel
2010-10-08 20:06 ` Michel Lespinasse
2010-10-09 1:22 ` Michel Lespinasse
2010-10-11 22:25 ` Andrew Morton
2010-10-11 22:43 ` Michel Lespinasse
2010-10-13 23:17 ` Andrew Morton
2010-10-06 4:02 ` H. Peter Anvin
2010-10-05 7:53 ` [PATCH 3/3] access_error API cleanup Michel Lespinasse
2010-10-05 19:44 ` Rik van Riel
2010-10-06 4:02 ` H. Peter Anvin
2010-10-06 4:14 ` Michel Lespinasse
2010-10-06 4:18 ` Andrew Morton
2010-10-06 4:20 ` H. Peter Anvin
2010-10-05 14:55 ` [PATCH 0/3] V2: Reduce mmap_sem hold times during file backed page faults Rik van Riel
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