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 SMTP id 8CEF0900001 for ; Thu, 28 Apr 2011 09:42:40 -0400 (EDT) Date: Thu, 28 Apr 2011 14:42:35 +0100 From: Mel Gorman Subject: Re: [PATCH 00/13] Swap-over-NBD without deadlocking Message-ID: <20110428134235.GW4658@suse.de> References: <1303803414-5937-1-git-send-email-mgorman@suse.de> <20110428133154.GA8572@ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20110428133154.GA8572@ucw.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Pavel Machek Cc: Linux-MM , Linux-Netdev , LKML , David Miller , Neil Brown , Peter Zijlstra On Thu, Apr 28, 2011 at 03:31:55PM +0200, Pavel Machek wrote: > Hi! > > > > For testing swap-over-NBD, a machine was booted with 2G of RAM with a > > swapfile backed by NBD. 16*NUM_CPU processes were started that create > > anonymous memory mappings and read them linearly in a loop. The total > > size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under > > memory pressure. Without the patches, the machine locks up within > > minutes and runs to completion with them applied. > > > > Comments? > > Nice! > > It is easy to see why swapping needs these fixes, but... dirty memory > writeout is used for memory clearing, too. Are same changes neccessary > to make that safe? > Dirty page limiting covers the MAP_SHARED cases and are already throttled approprately. > (Perhaps raise 'max dirty %' for testing?) Stress testing passed for dirty ratios of 40% at least. Maybe it would cause issues when raised to nearly 100% but I don't think that is a particularly interesting use case. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org