From: Andrew Morton Subject: Re: [PATCH] vmscan: set try_to_release_page's gfp_mask to 0 Date: Wed, 15 Oct 2008 19:54:58 -0700 Message-ID: <20081015195458.cc203dd5.akpm@linux-foundation.org> References: <6.0.0.20.2.20080813111835.03d345b0@172.19.0.2> <20080812202127.b88e8250.akpm@linux-foundation.org> <6.0.0.20.2.20080813150454.03b13e30@172.19.0.2> <20081015153641.afcc94e5.akpm@linux-foundation.org> <6.0.0.20.2.20081016112735.04a68e70@172.19.0.2> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, cmm@us.ibm.com To: Hisashi Hifumi Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:38357 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753424AbYJPCzL (ORCPT ); Wed, 15 Oct 2008 22:55:11 -0400 In-Reply-To: <6.0.0.20.2.20081016112735.04a68e70@172.19.0.2> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, 16 Oct 2008 11:44:39 +0900 Hisashi Hifumi wrote: > Hi Andrew. > > >Hisashi Hifumi wrote: > > > >> At 12:21 08/08/13, Andrew Morton wrote: > >> >On Wed, 13 Aug 2008 11:21:16 +0900 Hisashi Hifumi > >> > wrote: > > >> >> Signed-off-by: Hisashi Hifumi > >> >> > >> >> diff -Nrup linux-2.6.27-rc2.org/mm/vmscan.c > >linux-2.6.27-rc2.vmscan/mm/vmscan.c > >> >> --- linux-2.6.27-rc2.org/mm/vmscan.c 2008-08-11 14:33:24.000000000 +0900 > >> >> +++ linux-2.6.27-rc2.vmscan/mm/vmscan.c 2008-08-12 18:57:05.000000000 +0900 > >> >> @@ -614,7 +614,7 @@ static unsigned long shrink_page_list(st > >> >> * Otherwise, leave the page on the LRU so it is swappable. > >> >> */ > >> >> if (PagePrivate(page)) { > >> >> - if (!try_to_release_page(page, sc->gfp_mask)) > >> >> + if (!try_to_release_page(page, 0)) > >> >> goto activate_locked; > >> >> if (!mapping && page_count(page) == 1) { > >> >> unlock_page(page); > >> > > >> >I think the change makes sense. > >> > > >> >Has this change been shown to improve any workloads? If so, please > >> >provide full information for the changelog. If not, please mention > >> >this and explain why benefits were not demonstrable. This information > >> >should _always_ be present in a "performance" patch's changelog! > >> > >> Sorry, I do not have performance number yet. I'll try this. > >> > > > > Unfortunately, I did not succeed to get good performance number that > prove this patch had some benefit. OK, thanks, I dropped it. > >This patch remains in a stalled state... > > > >And then there's this: > > > > >: > >: Really, I think what this patch tells us is that 3f31fddf ("jbd: fix > >: race between free buffer and commit transaction") was an unpleasant > >: hack which had undesirable and unexpected side-effects. I think - that > >: depends upon your as-yet-undisclosed testing results? > >: > >: Perhaps we should revert 3f31fddf and have another think about how to > >: fix the direct-io -EIO problem. One option would be to hold our noses > >: and add a new gfp_t flag for this specific purpose? > >: > > direct-io -EIO problem was already fixed by following patch. > > commit 6ccfa806a9cfbbf1cd43d5b6aa47ef2c0eb518fd > Author: Hisashi Hifumi > Date: Tue Sep 2 14:35:40 2008 -0700 > > VFS: fix dio write returning EIO when try_to_release_page fails > > Dio falls back to buffered write when dio write gets EIO due to failure of try_to_release_page > by above patch. So I think just reverting the patch 3f31fddf ("jbd: fix race between > free buffer and commit transaction") is good approach. Fair enough. Could I ask that you (or someone) send a suitable patch sometime? I could generate the patch, but I'd never get around to testing it. Too busy fixing rejects and compile errors :(