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 ESMTP id 8F8866B0071 for ; Thu, 10 Jun 2010 20:08:57 -0400 (EDT) Received: from d01relay01.pok.ibm.com (d01relay01.pok.ibm.com [9.56.227.233]) by e6.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id o5B07IQi015085 for ; Thu, 10 Jun 2010 20:07:18 -0400 Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay01.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o5B07YOb132998 for ; Thu, 10 Jun 2010 20:07:34 -0400 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id o5B07YEQ030239 for ; Thu, 10 Jun 2010 20:07:34 -0400 Subject: Re: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page cache control From: Dave Hansen In-Reply-To: <20100610142512.GB5191@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> Content-Type: text/plain Date: Thu, 10 Jun 2010 17:07:32 -0700 Message-Id: <1276214852.6437.1427.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 Thu, 2010-06-10 at 19:55 +0530, Balbir Singh wrote: > > I'm not sure victimizing unmapped cache pages is a good idea. > > Shouldn't page selection use the LRU for recency information instead > > of the cost of guest reclaim? Dropping a frequently used unmapped > > cache page can be more expensive than dropping an unused text page > > that was loaded as part of some executable's initialization and > > forgotten. > > We victimize the unmapped cache only if it is unused (in LRU order). > We don't force the issue too much. We also have free slab cache to go > after. Just to be clear, let's say we have a mapped page (say of /sbin/init) that's been unreferenced since _just_ after the system booted. We also have an unmapped page cache page of a file often used at runtime, say one from /etc/resolv.conf or /etc/passwd. Which page will be preferred for eviction with this patch set? -- 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