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 860FC8D0039 for ; Fri, 28 Jan 2011 14:34:57 -0500 (EST) Message-ID: <4D431A47.90408@redhat.com> Date: Fri, 28 Jan 2011 14:34:31 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: too big min_free_kbytes References: <20110127160301.GA29291@csn.ul.ie> <20110127185215.GE16981@random.random> <20110127213106.GA25933@csn.ul.ie> <4D41FD2F.3050006@redhat.com> <20110128103539.GA14669@csn.ul.ie> <20110128162831.GH16981@random.random> <20110128164624.GA23905@csn.ul.ie> <4D42F9E3.2010605@redhat.com> <20110128174644.GM16981@random.random> <4D430506.2070502@redhat.com> <20110128182407.GO16981@random.random> In-Reply-To: <20110128182407.GO16981@random.random> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrea Arcangeli Cc: Mel Gorman , Shaohua Li , Andrew Morton , linux-mm , "Chen, Tim C" List-ID: On 01/28/2011 01:24 PM, Andrea Arcangeli wrote: > On Fri, Jan 28, 2011 at 01:03:50PM -0500, Rik van Riel wrote: >> My point is, the behaviour you describe would be WRONG :) >> >> The reason is that the different zones can contain data >> that is either heavily used or rarely used, often some >> mixture of the two, but sometimes the zones are out of >> balance in how much the data in memory gets touched. >> >> We need to reclaim and reuse the lightly used memory >> a little faster than the heavily used memory, to even >> out the memory pressure between zones. > > I've no idea how kswapd can reclaim the lightly used memory a little > faster when it blocks at high+gap. It will block at high+gap only when one zone has really easily reclaimable memory, and another zone has difficult to free memory. That creates a free memory differential between the easy to free and difficult to free memory zones. If memory in all zones is equally easy to free, kswapd will go to sleep once the high watermark is reached in every zone. -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org