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 65F998D0039 for ; Fri, 28 Jan 2011 15:55:37 -0500 (EST) Message-ID: <4D432D2D.4020504@redhat.com> Date: Fri, 28 Jan 2011 15:55:09 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: too big min_free_kbytes References: <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> <4D431A47.90408@redhat.com> <20110128194542.GV16981@random.random> In-Reply-To: <20110128194542.GV16981@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 02:45 PM, Andrea Arcangeli wrote: > On Fri, Jan 28, 2011 at 02:34:31PM -0500, Rik van Riel wrote: >> It will block at high+gap only when one zone has really >> easily reclaimable memory, and another zone has difficult >> to free memory. > > The other zone doesn't need to be difficult to free up. All ram in > immediately freeable clean cache is the most common case there is. And > it's more than enough to trigger the scenario in prev email. > >> That creates a free memory differential between the >> easy to free and difficult to free memory zones. > > There's no difficult to free zone in this scenario. In that case, every zone will go down to the low watermark before kswapd is woken up. At that point, kswapd will reclaim until every zone is at the high watermark, and go back to sleep. There is no "free up to high + gap" in your scenario. -- 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