From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mario Smarduch Subject: maybe a virtio-balloon-device issue ? Date: Thu, 05 Feb 2015 17:18:57 -0800 Message-ID: <54D41681.7080401@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "christoffer.dall@linaro.org" , Paolo Bonzini , Marc Zyngier , Gleb Natapov , Peter Maydell To: "kvm@vger.kernel.org" , "kvmarm@lists.cs.columbia.edu" Return-path: Received: from mailout3.w2.samsung.com ([211.189.100.13]:9438 "EHLO usmailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751355AbbBFBTB (ORCPT ); Thu, 5 Feb 2015 20:19:01 -0500 Received: from uscpsbgex1.samsung.com (u122.gpu85.samsung.co.kr [203.254.195.122]) by usmailout3.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NJB00958SZNX9B0@usmailout3.samsung.com> for kvm@vger.kernel.org; Thu, 05 Feb 2015 20:19:00 -0500 (EST) Sender: kvm-owner@vger.kernel.org List-ID: 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. Thanks.