From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id BB7656B006A for ; Tue, 5 Oct 2010 18:44:34 -0400 (EDT) Received: from hpaq1.eem.corp.google.com (hpaq1.eem.corp.google.com [172.25.149.1]) by smtp-out.google.com with ESMTP id o95MiPW6030179 for ; Tue, 5 Oct 2010 15:44:32 -0700 Received: from iwn4 (iwn4.prod.google.com [10.241.68.68]) by hpaq1.eem.corp.google.com with ESMTP id o95MgQ8g021299 for ; Tue, 5 Oct 2010 15:44:23 -0700 Received: by iwn4 with SMTP id 4so13919096iwn.10 for ; Tue, 05 Oct 2010 15:44:23 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <4CAB628D.3030205@redhat.com> References: <1286265215-9025-1-git-send-email-walken@google.com> <1286265215-9025-3-git-send-email-walken@google.com> <4CAB628D.3030205@redhat.com> Date: Tue, 5 Oct 2010 15:44:22 -0700 Message-ID: Subject: Re: [PATCH 2/3] Retry page fault when blocking on disk transfer. From: Michel Lespinasse Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: linux-mm@kvack.org, Linus Torvalds , Ying Han , linux-kernel@vger.kernel.org, Andrew Morton , Nick Piggin , Peter Zijlstra List-ID: On Tue, Oct 5, 2010 at 10:38 AM, Rik van Riel 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 > > Acked-by: Rik van Riel > > 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org