From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v3 1/3] Introduce a workqueue to deliver PIT timer interrupts. Date: Tue, 17 Apr 2012 13:42:31 +0300 Message-ID: <4F8D4917.5000703@redhat.com> References: <1276722673-19011-1-git-send-email-clalance@redhat.com> <1276722673-19011-2-git-send-email-clalance@redhat.com> <4F8C49D6.9010603@siemens.com> <20120417093123.GB11918@redhat.com> <4F8D44B8.1000102@redhat.com> <20120417102601.GF11918@redhat.com> <4F8D45F0.4020908@redhat.com> <20120417103106.GG11918@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Jan Kiszka , kvm@vger.kernel.org, Marcelo Tosatti To: Gleb Natapov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:21765 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752656Ab2DQKmf (ORCPT ); Tue, 17 Apr 2012 06:42:35 -0400 In-Reply-To: <20120417103106.GG11918@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 04/17/2012 01:31 PM, Gleb Natapov wrote: > On Tue, Apr 17, 2012 at 01:29:04PM +0300, Avi Kivity wrote: > > On 04/17/2012 01:26 PM, Gleb Natapov wrote: > > > > It isn't, since you need to send an IPI. > > > > > > > That is exactly what I forget whether you can send IPI from there :) > > > Anyway this is another reason. > > > > > > > Actually I was wrong. You can't smp_call_function_single() from irq > > context (deadlocks if two vcpus do that), but we send a reschedule > > interrupt. So it should work. > > > Ah, good point. So if we'll use irqsave versions of spinlocks we can > drop kthread? Do we want 254 IPIs to be issued from irq context? Could be slow. We can make the unicast case run from irq context and defer the multicast to a thread. -- error compiling committee.c: too many arguments to function