From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 8EB876B0092 for ; Fri, 8 Oct 2010 09:24:47 -0400 (EDT) Message-ID: <4CAF1B90.3080703@redhat.com> Date: Fri, 08 Oct 2010 09:24:32 -0400 From: Rik van Riel MIME-Version: 1.0 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> <4CAB628D.3030205@redhat.com> <20101008043956.GA25662@google.com> In-Reply-To: <20101008043956.GA25662@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Michel Lespinasse Cc: Linus Torvalds , linux-mm@kvack.org, Ying Han , linux-kernel@vger.kernel.org, Andrew Morton , Nick Piggin , Peter Zijlstra List-ID: On 10/08/2010 12:39 AM, Michel Lespinasse wrote: > On Tue, Oct 05, 2010 at 03:44:22PM -0700, Michel Lespinasse wrote: >> On Tue, Oct 5, 2010 at 10:38 AM, Rik van Riel wrote: >>> 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. > > So here's the patch. Sorry for the delay - it did not take long to write, > but I couldn't test it before today. > > Please have a look - I'd like to add this to the series I sent earlier. > > ----------------------------------- 8< --------------------------------- > > Retry page fault when blocking on swap in > > This change is the cousin of 'Retry page fault when blocking > on disk transfer'. The idea here is to reduce mmap_sem hold times > that are caused by disk transfers when swapping in pages. We drop > mmap_sem while waiting for the page lock, and return the VM_FAULT_RETRY > flag. do_page_fault will then re-acquire mmap_sem and retry the > page fault. It is expected that upon retry the page will now be cached, > and thus the retry will complete with a low mmap_sem hold time. > > Signed-off-by: Michel Lespinasse > > diff --git a/mm/memory.c b/mm/memory.c > index b068c68..0ec70b4 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2613,6 +2613,21 @@ int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) > return 0; > } > > +static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm, > + unsigned int flags) > +{ > + if (trylock_page(page)) > + return 1; > + if (!(flags& FAULT_FLAG_ALLOW_RETRY)) { > + __lock_page(page); > + return 1; > + } > + > + up_read(&mm->mmap_sem); > + wait_on_page_locked(page); > + return 0; > +} Wait a moment. Your other patch 2/3 also has a lock_page_or_retry function. That one is in filemap.c and takes slightly different arguments, to do essentially the same thing... +/* + * Lock the page, unless this would block and the caller indicated that it + * can handle a retry. + */ +static int lock_page_or_retry(struct page *page, + struct vm_area_struct *vma, struct vm_fault *vmf) +{ Is there a way the two functions can be merged into one? -- All rights reversed -- 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