From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 6809B6B006A for ; Fri, 13 Nov 2009 08:41:48 -0500 (EST) Received: by gv-out-0910.google.com with SMTP id l14so427127gvf.19 for ; Fri, 13 Nov 2009 05:41:46 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20091113133211.GA8742@kernel.dk> References: <1258054235-3208-1-git-send-email-mel@csn.ul.ie> <1258054235-3208-4-git-send-email-mel@csn.ul.ie> <20091113142526.33B3.A69D9226@jp.fujitsu.com> <20091113115558.GY8742@kernel.dk> <20091113122821.GC29804@csn.ul.ie> <20091113133211.GA8742@kernel.dk> Date: Fri, 13 Nov 2009 15:41:46 +0200 Message-ID: <84144f020911130541p42c0b3d5lc307f97f22e2d356@mail.gmail.com> Subject: Re: [PATCH 3/5] page allocator: Wait on both sync and async congestion after direct reclaim From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org To: Jens Axboe Cc: Mel Gorman , KOSAKI Motohiro , Andrew Morton , Frans Pop , Jiri Kosina , Sven Geggus , Karol Lewandowski , Tobias Oetiker , linux-kernel@vger.kernel.org, "linux-mm@kvack.org" , Rik van Riel , Christoph Lameter , Stephan von Krawczynski , "Rafael J. Wysocki" , Kernel Testers List , Linus Torvalds List-ID: Hi Jens, On Fri, Nov 13, 2009 at 3:32 PM, Jens Axboe wrote: >> Suggest an alternative that brings congestion_wait() more in line with >> 2.6.30 behaviour then. > > I don't have a good explanation as to why the delays have changed, > unfortunately. Are we sure that they have between .30 and .31? The > dm-crypt case is overly complex and lots of changes could have broken > that house of cards. Hand-waving or not, we have end user reports stating that reverting commit 8aa7e847d834ed937a9ad37a0f2ad5b8584c1ab0 ("Fix congestion_wait() sync/async vs read/write confusion") fixes their (rather serious) OOM regression. The commit in question _does_ introduce a functional change and if this was your average regression, people would be kicking and screaming to get it reverted. So is there a reason we shouldn't send a partial revert of the commit (switching to BLK_RW_SYNC) to Linus until the "real" issue gets resolved? Yes, I realize it's ugly voodoo magic but dammit, it used to work! Pekka -- 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