From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 969FA6B0044 for ; Wed, 4 Nov 2009 10:49:00 -0500 (EST) Date: Wed, 4 Nov 2009 15:48:53 +0000 From: Mel Gorman Subject: Re: [PATCH 3/3] vmscan: Force kswapd to take notice faster when high-order watermarks are being hit Message-ID: <20091104154853.GM22046@csn.ul.ie> References: <1256650833-15516-1-git-send-email-mel@csn.ul.ie> <200911040101.50194.elendil@planet.nl> <20091104011811.GG22046@csn.ul.ie> <200911040305.59352.elendil@planet.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <200911040305.59352.elendil@planet.nl> Sender: owner-linux-mm@kvack.org To: Frans Pop Cc: Andrew Morton , stable@kernel.org, linux-kernel@vger.kernel.org, "linux-mm@kvack.org" , Jiri Kosina , Sven Geggus , Karol Lewandowski , Tobias Oetiker , KOSAKI Motohiro , Pekka Enberg , Rik van Riel , Christoph Lameter , Stephan von Krawczynski , Kernel Testers List List-ID: On Wed, Nov 04, 2009 at 03:05:55AM +0100, Frans Pop wrote: > On Wednesday 04 November 2009, Mel Gorman wrote: > > > If you'd like me to test with the congestion_wait() revert on top of > > > this for comparison, please let me know. > > > > No, there is resistance to rolling back the congestion_wait() changes > > I've never promoted the revert as a solution. It just shows the cause of a > regression. > Yeah, I still haven't managed to figure out what exactly is wrong in there other than "something changed with timing" and writeback behaves differently. I still don't know the why of it because I haven't digged into that area in depth in the past and failed at reproducing this. "My desktop is fine" :/ > > from what I gather because they were introduced for sane reasons. The > > consequence is just that the reliability of high-order atomics are > > impacted because more processes are making forward progress where > > previously they would have waited until kswapd had done work. Your > > driver has already been fixed in this regard and maybe it's a case that > > the other atomic users simply have to be fixed to "not do that". > > The problem is that although my driver has been fixed so that it no longer > causes the SKB allocation errors, the also rather serious behavior change > where due to swapping my 3rd gitk takes up to twice as long to load with > desktop freezes of up 45 seconds or so is still there. > > Although that's somewhat separate from the issue that started this whole > investigation, I still feel that should be sorted out as well. > You're right. That behaviour sucks. > The congestion_wait() change, even if theoretically valid, introduced a > very real regression IMO. Such long desktop freezes during swapping should > be avoided; .30 and earlier simply behaved a whole lot better in the same > situation. > Agreed. I'll start from scratch again trying to reproduce what you're seeing locally. I'll try breaking my network card so that it's making high-order atomics and see where I get. Machines that were previously tied up are now free so I might have a better chance. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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