From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [RFC PATCH 0/3] Avoid soft lockup message when KVM is stopped by host Date: Thu, 04 Aug 2011 13:46:42 -0500 Message-ID: <4E3AE912.7050402@us.ibm.com> References: <1312381501-27746-1-git-send-email-emunson@mgebm.net> <4E3A5A38.9080406@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Eric B Munson , kvm@vger.kernel.org, kvm-ia64@vger.kernel.org, kvm-ppc@vger.kernel.org, avi@redhat.com, riel@redhat.com, glommer@redhat.com, linux-kernel@vger.kernel.org, Ryan A Harper , Glauber Costa To: dlaor@redhat.com Return-path: In-Reply-To: <4E3A5A38.9080406@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 08/04/2011 03:37 AM, Dor Laor wrote: > On 08/03/2011 05:24 PM, Eric B Munson wrote: >> This set is just a rough first pass at avoiding soft lockup warnings >> when a host >> pauses the execution of a guest. A flag is set by the host in the >> shared page >> used for the pvclock when the host goes to stop the guest. When the guest >> resumes and detects a soft lockup, this flag is checked and cleared >> and the soft >> lockup message is skipped. > > While this will cover the case were the host stops a guest, there will > be other plain cases where the host is just over committed and will > cause a softlockup false positive on the guest. > > Softlockup should use stolen time that makes use of the guest running > info would cover both cases At least in the current steal time implementation, there are numerous cases where steal time is not accounted but you'd hit a soft lockup. Pausing an idle guest via (qemu) stop is an example. Likewise, a guest that is descheduled while idle but then not scheduled for prolonged periods of time would also not be accounted as steal time. Regards, Anthony Liguori