From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751551Ab0JFEDu (ORCPT ); Wed, 6 Oct 2010 00:03:50 -0400 Received: from terminus.zytor.com ([198.137.202.10]:45257 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750720Ab0JFEDt (ORCPT ); Wed, 6 Oct 2010 00:03:49 -0400 Message-ID: <4CABF4C0.8060405@zytor.com> Date: Tue, 05 Oct 2010 21:02:08 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc13 Thunderbird/3.1.4 MIME-Version: 1.0 To: Michel Lespinasse CC: linux-mm@kvack.org, Linus Torvalds , Ying Han , linux-kernel@vger.kernel.org, Andrew Morton , Rik van Riel , Nick Piggin , Peter Zijlstra , Andrew Morton Subject: Re: [PATCH 2/3] Retry page fault when blocking on disk transfer. References: <1286265215-9025-1-git-send-email-walken@google.com> <1286265215-9025-3-git-send-email-walken@google.com> In-Reply-To: <1286265215-9025-3-git-send-email-walken@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/05/2010 12:53 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 > --- > arch/x86/mm/fault.c | 38 ++++++++++++++++++++++++++------------ > include/linux/mm.h | 2 ++ > mm/filemap.c | 23 ++++++++++++++++++++++- > mm/memory.c | 3 ++- > 4 files changed, 52 insertions(+), 14 deletions(-) > Acked-by: H. Peter Anvin -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.