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 ESMTP id F1C166B0212 for ; Mon, 14 Jun 2010 11:13:32 -0400 (EDT) Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e38.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id o5EF6jDe016224 for ; Mon, 14 Jun 2010 09:06:46 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id o5EFDNMY173572 for ; Mon, 14 Jun 2010 09:13:24 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id o5EFDISd027652 for ; Mon, 14 Jun 2010 09:13:19 -0600 Subject: Re: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page cache control From: Dave Hansen In-Reply-To: <20100614084810.GT5191@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> Content-Type: text/plain Date: Mon, 14 Jun 2010 08:12:56 -0700 Message-Id: <1276528376.6437.7176.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 14:18 +0530, Balbir Singh wrote: > 1. A slab page will not be freed until the entire page is free (all > slabs have been kfree'd so to speak). Normal reclaim will definitely > free this page, but a lot of it depends on how frequently we are > scanning the LRU list and when this page got added. You don't have to be freeing entire slab pages for the reclaim to have been useful. You could just be making space so that _future_ allocations fill in the slab holes you just created. You may not be freeing pages, but you're reducing future system pressure. If unmapped page cache is the easiest thing to evict, then it should be the first thing that goes when a balloon request comes in, which is the case this patch is trying to handle. If it isn't the easiest thing to evict, then we _shouldn't_ evict it. -- 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