From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f198.google.com (mail-wj0-f198.google.com [209.85.210.198]) by kanga.kvack.org (Postfix) with ESMTP id 740D56B0069 for ; Tue, 7 Feb 2017 04:54:13 -0500 (EST) Received: by mail-wj0-f198.google.com with SMTP id h7so24303712wjy.6 for ; Tue, 07 Feb 2017 01:54:13 -0800 (PST) Received: from outbound-smtp03.blacknight.com (outbound-smtp03.blacknight.com. [81.17.249.16]) by mx.google.com with ESMTPS id n10si4366389wrb.298.2017.02.07.01.54.12 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 07 Feb 2017 01:54:12 -0800 (PST) Received: from mail.blacknight.com (pemlinmail06.blacknight.ie [81.17.255.152]) by outbound-smtp03.blacknight.com (Postfix) with ESMTPS id 0CE13989FC for ; Tue, 7 Feb 2017 09:54:12 +0000 (UTC) Date: Tue, 7 Feb 2017 09:54:10 +0000 From: Mel Gorman Subject: Re: [PATCH] vmscan: fix zone balance check in prepare_kswapd_sleep Message-ID: <20170207095410.6xflcfktwlofbg3f@techsingularity.net> References: <719282122.1183240.1486298780546.ref@mail.yahoo.com> <719282122.1183240.1486298780546@mail.yahoo.com> <20170206161715.sfz6lm3vmahlnxx6@techsingularity.net> <68644e18-ed8d-0559-4ac2-fb3162f6ba67@yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <68644e18-ed8d-0559-4ac2-fb3162f6ba67@yahoo.com> Sender: owner-linux-mm@kvack.org List-ID: To: Shantanu Goel Cc: "linux-mm@kvack.org" On Mon, Feb 06, 2017 at 07:16:46PM -0500, Shantanu Goel wrote: > > However, note that there is a slight risk that kswapd will sleep for a > > short interval early due to a very small zone such as ZONE_DMA. If this > > is a general problem then it'll manifest as less kswapd reclaim and more > > direct reclaim. If it turns out this is an issue then a revert will not > > be the right fix. Instead, all the checks for zone_balance will need to > > account for the only balanced zone being a tiny percentage of memory in > > the node. > > > > I see your point. Perhaps we can introduce a constraint that > ensures the balanced zones constitute say 1/4 or 1/2 of > memory in the classzone? I believe there used to be such > a constraint at one time for higher order allocations. > There was but it was fairly complex and I'd rather avoid it if at all possible and certainly not without data backing it up. -- Mel Gorman SUSE Labs -- 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