Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756706Ab0DFR2j (ORCPT ); Tue, 6 Apr 2010 13:28:39 -0400 Received: from rcsinet12.oracle.com ([148.87.113.124]:48972 "EHLO rcsinet12.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755868Ab0DFR2f convert rfc822-to-8bit (ORCPT ); Tue, 6 Apr 2010 13:28:35 -0400 MIME-Version: 1.0 Message-ID: <0866dc77-b531-4128-bb63-0d4859099bc8@default> Date: Tue, 6 Apr 2010 10:27:39 -0700 (PDT) From: Dan Magenheimer To: Avi Kivity , Andrew Morton Cc: Jeremy Fitzhardinge , Dmitry Torokhov , linux-kernel@vger.kernel.org, pv-drivers@vmware.com Subject: RE: [PATCH] VMware Balloon driver References: <20100404215202.GA13020@dtor-ws.eng.vmware.com> <20100405142419.2c9bea3d.akpm@linux-foundation.org> <4BBA5E1C.10706@goop.org> <20100405151720.8a6ac5e3.akpm@linux-foundation.org> <4BBA7226.9080508@goop.org> <20100405163458.135fa319.akpm@linux-foundation.org 4BBB61AF.6000608@redhat.com> In-Reply-To: <4BBB61AF.6000608@redhat.com> X-Priority: 3 X-Mailer: Oracle Beehive Extensions for Outlook 1.5.1.5.2 (401224) [OL 12.0.6514.5000] Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT X-Source-IP: acsmt354.oracle.com [141.146.40.154] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090209.4BBB6F27.0163:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1278 Lines: 31 > From: Avi Kivity [mailto:avi@redhat.com] > Sent: Tuesday, April 06, 2010 10:31 AM > > > >> And is there some way to get the vm subsystem to provide > backpressure: > >> "I'm getting desperately short of memory!"? > >> > > Not really. One could presumably pull dopey tricks by hooking into > > slab shrinker registration or even ->writepage(). But cooking up > > something explicit doesn't sound too hard - the trickiest bit would > be > > actually defining what it should do. > > The oft-suggested approach is to look at the I/O load from guests and > give more memory to those that are thrashing. Of course not all I/O is > directly due to memory pressure. Which is why it is very useful to be able to differentiate between: 1) refault I/O (due to pagecache too small, and PFRA choices) 2) swap I/O (due to memory pressure) 3) normal file dirty writes (due to an app's need for persistence) Again, the cleancache and frontswap hooks and APIs separate these out nicely. Dan "who worries he is sounding like a broken record" -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/