From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757929Ab1LNS1J (ORCPT ); Wed, 14 Dec 2011 13:27:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46018 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755498Ab1LNS1H (ORCPT ); Wed, 14 Dec 2011 13:27:07 -0500 Date: Wed, 14 Dec 2011 16:21:01 -0200 From: Marcelo Tosatti To: Avi Kivity Cc: Eric B Munson , mingo@redhat.com, hpa@zytor.com, arnd@arndb.de, ryanh@linux.vnet.ibm.com, aliguori@us.ibm.com, jeremy.fitzhardinge@citrix.com, levinsasha928@gmail.com, Jan Kiszka , kvm@vger.kernel.org, linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/5 V5] Avoid soft lockup message when KVM is stopped by host Message-ID: <20111214182101.GB21945@amt.cnet> References: <1323116344-17911-1-git-send-email-emunson@mgebm.net> <4EDF7B0D.4060001@redhat.com> <20111214121622.GB18317@amt.cnet> <4EE8B53C.6070502@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4EE8B53C.6070502@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 14, 2011 at 04:39:56PM +0200, Avi Kivity wrote: > On 12/14/2011 02:16 PM, Marcelo Tosatti wrote: > > > Having this controlled from userspace means it doesn't work for SIGSTOP > > > or for long scheduling delays. What about doing this automatically > > > based on preempt notifiers? > > > > Long scheduling delays should be considered hangups from the guest > > perspective. > > Why? To the guest it looks like slow hardware, but it will interpret it > as a softlockup. Slow enough that progress of the watchdog thread is unable to keep up with timer interrupt processing. This is considered a hang and should be reported. > > About SIGSTOP, that is a corner case. Unsure if its even properly supported > > by QEMU. > > It works from my experience.