From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM: pit: Do not check pending pit timer in vcpu thread Date: Tue, 31 Aug 2010 09:25:55 +0300 Message-ID: <4C7CA073.1050906@redhat.com> References: <20100827091506.10369.58066.stgit@FreeLancer> <4C7C23AD.3090907@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Jason Wang , mtosatti@redhat.com, kvm , Chris Lalancette To: Zachary Amsden Return-path: Received: from mx1.redhat.com ([209.132.183.28]:10301 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756516Ab0HaGZ7 (ORCPT ); Tue, 31 Aug 2010 02:25:59 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o7V6PxrB021127 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 31 Aug 2010 02:25:59 -0400 In-Reply-To: <4C7C23AD.3090907@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/31/2010 12:33 AM, Zachary Amsden wrote: > On 08/26/2010 11:15 PM, Jason Wang wrote: >> Pit interrupt injection was done by workqueue, so no need to check >> pending pit timer in vcpu thread which could lead unnecessary >> unblocking of vcpu. > > Is this actually correct? There were a bunch of workarounds and fixes > put into this code over time. Please check with Chris Lalancette, I > think he was the last to touch this code. Once upon a time we injected PIT interrupts from the vcpu thread (even though the PIT is external to any vcpu) which let to a lot of complications in the implementation. This patch removes one of them. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.