Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759885AbcCDSv3 (ORCPT ); Fri, 4 Mar 2016 13:51:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53357 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759765AbcCDSv1 (ORCPT ); Fri, 4 Mar 2016 13:51:27 -0500 Date: Fri, 4 Mar 2016 18:51:21 +0000 From: "Dr. David Alan Gilbert" To: Paolo Bonzini Cc: "Li, Liang Z" , Roman Kagan , "ehabkost@redhat.com" , "kvm@vger.kernel.org" , "mst@redhat.com" , "quintela@redhat.com" , "linux-kernel@vger.kernel.org" , "qemu-devel@nongnu.org" , "linux-mm@kvack.org" , "amit.shah@redhat.com" , "akpm@linux-foundation.org" , "virtualization@lists.linux-foundation.org" , "rth@twiddle.net" Subject: Re: [Qemu-devel] [RFC qemu 0/4] A PV solution for live migration optimization Message-ID: <20160304185120.GB2588@work-vm> References: <1457001868-15949-1-git-send-email-liang.z.li@intel.com> <20160303174615.GF2115@work-vm> <20160304081411.GD9100@rkaganb.sw.ru> <20160304102346.GB2479@rkaganb.sw.ru> <56D9B6C2.3070708@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56D9B6C2.3070708@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1305 Lines: 38 * Paolo Bonzini (pbonzini@redhat.com) wrote: > > > On 04/03/2016 15:26, Li, Liang Z wrote: > >> > > >> > The memory usage will keep increasing due to ever growing caches, etc, so > >> > you'll be left with very little free memory fairly soon. > >> > > > I don't think so. > > > > Roman is right. For example, here I am looking at a 64 GB (physical) > machine which was booted about 30 minutes ago, and which is running > disk-heavy workloads (installing VMs). > > Since I have started writing this email (2 minutes?), the amount of free > memory has already gone down from 37 GB to 33 GB. I expect that by the > time I have finished running the workload, in two hours, it will not > have any free memory. But what about a VM sitting idle, or that just has more RAM assigned to it than is currently using. I've got a host here that's been up for 46 days and has been doing some heavy VM debugging a few days ago, but today: # free -m total used free shared buff/cache available Mem: 96536 1146 44834 184 50555 94735 I very rarely use all it's RAM, so it's got a big chunk of free RAM, and yes it's got a big chunk of cache as well. Dave > > Paolo -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK