From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: maybe a virtio-balloon-device issue ? Date: Fri, 06 Feb 2015 16:57:13 +0100 Message-ID: <54D4E459.9040007@redhat.com> References: <54D41681.7080401@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: "christoffer.dall@linaro.org" , Marc Zyngier , Gleb Natapov , Peter Maydell To: Mario Smarduch , "kvm@vger.kernel.org" , "kvmarm@lists.cs.columbia.edu" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47108 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753222AbbBFP5e (ORCPT ); Fri, 6 Feb 2015 10:57:34 -0500 In-Reply-To: <54D41681.7080401@samsung.com> Sender: kvm-owner@vger.kernel.org List-ID: On 06/02/2015 02:18, Mario Smarduch wrote: > Hi, > > I'm looking into qemu/balloon driver VM overcommit. I noticed > virtio-balloon driver will take any setting from virtio-balloon-device > to the point Guest dies. > > For a 1G guest > $ sudo echo balloon 100 | socat - tcp4-connect:127.0.0.1:4444 > > you get (same with libvirt setmem) > > root@localhost:~# free > -bash: fork: Cannot allocate memory > root@localhost:~# ps > -bash: fork: Cannot allocate memory > > $ sudo info balloon | socat ... - confirms setting > > The balloon driver has been there for a while, not sure what I'm missing? > > virtio-balloon-device provide free memory, i.e., - externally accessible > to host. But this appears more like a hint for an inflate request, snmp > mibs > provide more detailed resource info then that. > > I'm wondering if the driver should not have some heuristic > check for an inflate request so it doesn't over inflate? Similar to > kernel overcommit. See this patch: commit 5a10b7dbf904bfe01bb9fcc6298f7df09eed77d5 Author: Raushaniya Maksudova Date: Mon Nov 10 09:36:29 2014 +1030 virtio_balloon: free some memory from balloon on OOM Looks like the QEMU part was never posted though. Paolo