From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH v2] KVM: x86: Remove support for reporting coalesced APIC IRQs Date: Thu, 2 May 2013 22:14:32 -0300 Message-ID: <20130503011432.GB5467@amt.cnet> References: <517D0784.7040400@web.de> <20130428114329.GK30504@redhat.com> <517D0F69.5080902@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Gleb Natapov , kvm To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:64965 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761979Ab3ECBO5 (ORCPT ); Thu, 2 May 2013 21:14:57 -0400 Content-Disposition: inline In-Reply-To: <517D0F69.5080902@web.de> Sender: kvm-owner@vger.kernel.org List-ID: On Sun, Apr 28, 2013 at 02:00:41PM +0200, Jan Kiszka wrote: > From: Jan Kiszka > > Since the arrival of posted interrupt support we can no longer guarantee > that coalesced IRQs are always reported to the IRQ source. Moreover, > accumulated APIC timer events could cause a busy loop when a VCPU should > rather be halted. The consensus is to remove coalesced tracking from the > LAPIC. > > Signed-off-by: Jan Kiszka > --- > > Changes in v2: > - preserve return values where we need to count to how many VCPUs an > IRQ was delivered It would be best to confirm first that no guest depends on LAPIC timer reinjection (rather than wait for guests to break and spend time debugging). Specially since such kind of bugs are not easy to pinpoint. Or if there is evidence to invalidate such reasoning, please point it out. Honestly i don't recall: would have to check RHEL5.32 UP/SMP, RHEL5.64 UP/SMP, RHEL4.32, RHEL4.64, RHEL6. Can do that in a week or so.