From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757478Ab0JEWo1 (ORCPT ); Tue, 5 Oct 2010 18:44:27 -0400 Received: from smtp-out.google.com ([74.125.121.35]:29817 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753225Ab0JEWo0 (ORCPT ); Tue, 5 Oct 2010 18:44:26 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=j0ckm+L80O0PsD3BbrwPy2PFHEz9lISPzfOJqeNHYAGWU+7YL51O2ziHXHFQB9eDvU i4qcQ+GucymICqD+PAtA== 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 To: Rik van Riel Cc: linux-mm@kvack.org, Linus Torvalds , Ying Han , linux-kernel@vger.kernel.org, Andrew Morton , Nick Piggin , Peter Zijlstra Content-Type: text/plain; charset=ISO-8859-1 X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.