From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by kanga.kvack.org (Postfix) with ESMTP id 26CB76B007E for ; Wed, 9 Mar 2016 01:18:04 -0500 (EST) Received: by mail-pa0-f48.google.com with SMTP id tt10so31064635pab.3 for ; Tue, 08 Mar 2016 22:18:04 -0800 (PST) Received: from mga03.intel.com (mga03.intel.com. [134.134.136.65]) by mx.google.com with ESMTP id wg10si10168598pac.23.2016.03.08.22.18.03 for ; Tue, 08 Mar 2016 22:18:03 -0800 (PST) From: "Li, Liang Z" Subject: RE: [Qemu-devel] [RFC qemu 0/4] A PV solution for live migration optimization Date: Wed, 9 Mar 2016 06:18:00 +0000 Message-ID: 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> In-Reply-To: <56D9B6C2.3070708@redhat.com> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Paolo Bonzini , Roman Kagan Cc: "Dr. David Alan Gilbert" , "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" > 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. > > >=20 > Roman is right. For example, here I am looking at a 64 GB (physical) mac= hine > which was booted about 30 minutes ago, and which is running disk-heavy > workloads (installing VMs). >=20 > 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. >=20 > Paolo I have a VM which has 2GB of RAM, when the guest booted, there were about 1= .4GB of free pages. Then I tried to download a large file from the internet with the browser, a= fter the downloading finished, there were only 72MB of free pages left, as Roman pointed out, there were q= uite a lot of Cached memory. Then I tried to compile the QEMU, after the compiling finished, there were = about 1.3G free pages. So even the cache will increase to a large amount, it will be freed if ther= e are some other specific workloads.=20 The cache memory is a big issue that should be taken into consideration. How about reclaim some cache before getting the free pages information? =20 Liang=20 -- 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