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 ESMTP id 7661F6B01C1 for ; Mon, 14 Jun 2010 13:09:38 -0400 (EDT) Received: from d01relay05.pok.ibm.com (d01relay05.pok.ibm.com [9.56.227.237]) by e8.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id o5EGw8ta023824 for ; Mon, 14 Jun 2010 12:58:08 -0400 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o5EH9Ytc132294 for ; Mon, 14 Jun 2010 13:09:34 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id o5EH9XCg022978 for ; Mon, 14 Jun 2010 14:09:33 -0300 Subject: Re: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page cache control From: Dave Hansen In-Reply-To: <20100614165853.GW5191@balbir.in.ibm.com> References: <20100608155140.3749.74418.sendpatchset@L34Z31A.ibm.com> <20100608155153.3749.31669.sendpatchset@L34Z31A.ibm.com> <4C10B3AF.7020908@redhat.com> <20100610142512.GB5191@balbir.in.ibm.com> <1276214852.6437.1427.camel@nimitz> <20100611045600.GE5191@balbir.in.ibm.com> <4C15E3C8.20407@redhat.com> <20100614084810.GT5191@balbir.in.ibm.com> <1276528376.6437.7176.camel@nimitz> <20100614165853.GW5191@balbir.in.ibm.com> Content-Type: text/plain Date: Mon, 14 Jun 2010 10:09:31 -0700 Message-Id: <1276535371.6437.7417.camel@nimitz> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: balbir@linux.vnet.ibm.com Cc: Avi Kivity , kvm , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Mon, 2010-06-14 at 22:28 +0530, Balbir Singh wrote: > If you've got duplicate pages and you know > that they are duplicated and can be retrieved at a lower cost, why > wouldn't we go after them first? I agree with this in theory. But, the guest lacks the information about what is truly duplicated and what the costs are for itself and/or the host to recreate it. "Unmapped page cache" may be the best proxy that we have at the moment for "easy to recreate", but I think it's still too poor a match to make these patches useful. -- Dave -- 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/ . Don't email: email@kvack.org