From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 406108D0039 for ; Tue, 22 Feb 2011 12:12:37 -0500 (EST) Date: Tue, 22 Feb 2011 18:11:58 +0100 From: Andrea Arcangeli Subject: Re: [PATCH v6 0/4] fadvise(DONTNEED) support Message-ID: <20110222171158.GC31195@random.random> References: <20110221190713.GM13092@random.random> <20110222132804.GQ13092@random.random> <4D63EC77.6070208@mnsu.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4D63EC77.6070208@mnsu.edu> Sender: owner-linux-mm@kvack.org List-ID: To: Jeffrey Hundstad Cc: Minchan Kim , Andrew Morton , linux-mm , LKML , Steven Barrett , Ben Gamari , Peter Zijlstra , Rik van Riel , Mel Gorman , KOSAKI Motohiro , Wu Fengguang , Johannes Weiner , Nick Piggin , Balbir Singh , KAMEZAWA Hiroyuki On Tue, Feb 22, 2011 at 11:03:51AM -0600, Jeffrey Hundstad wrote: > On 02/22/2011 07:28 AM, Andrea Arcangeli wrote: > > Hi Minchan, > > That's my point, we should check if the "thrashing horribly" is really > > a "recently" or if it has always happened before with 2.6.18 and previous. > > I would bet that "thrashing" isn't what he meant. He almost certainly > meant "needless I/O" and nothing to do with swapping. I've seen this > similar report before. This report is almost always gets answered with > a "set your swappiness to an appropriate value" type answer. Or a "your Hmm but swappiness can't help if "needless I/O in the morning after backup" is the problem. So it wouldn't be the right suggestion if "needless I/O is the problem". We need a "vmstat 1" during the "trashing horribly"/"needless I/O" in the morning to be sure. > userspace app needs to get smarter" type answer. I think they are > trying to do the latter, but need some help from the kernel, and that's > what they're trying to do here. That's fine thing. But I got reports indipendent of this thread from friends, asking me how to prevent swapping overnight because of backup, so I connected that report to the above "trashing horribly"/recently. I had no problems personally but may backup runs once (not twice to activate/reference pages). I had no time to investigate this further yet to see if things works ok for me even with a rsync loop activating and referencing everything. -- 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org