From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Subject: Re: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page cache control Date: Thu, 10 Jun 2010 17:07:32 -0700 Message-ID: <1276214852.6437.1427.camel@nimitz> 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> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Avi Kivity , kvm , linux-mm@kvack.org, linux-kernel@vger.kernel.org To: balbir@linux.vnet.ibm.com Return-path: In-Reply-To: <20100610142512.GB5191@balbir.in.ibm.com> Sender: owner-linux-mm@kvack.org List-Id: kvm.vger.kernel.org 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