From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751267AbaCVO5n (ORCPT ); Sat, 22 Mar 2014 10:57:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:16903 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750826AbaCVO5m (ORCPT ); Sat, 22 Mar 2014 10:57:42 -0400 Message-ID: <532DA4D8.60102@redhat.com> Date: Sat, 22 Mar 2014 10:57:28 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: lwcheng@cs.hku.hk CC: Glauber Costa , Peter Zijlstra , LKML Subject: Re: [BUG] Paravirtual time accounting / IRQ time accounting References: <20140319174222.213976eu8b54ujk0@intranet.cs.hku.hk> <532C232E.5000607@redhat.com> <20140322151540.9740576amzy5tdwk@intranet.cs.hku.hk> In-Reply-To: <20140322151540.9740576amzy5tdwk@intranet.cs.hku.hk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/22/2014 03:15 AM, lwcheng@cs.hku.hk wrote: > I observe that sometimes irq_time only includes "part" of steal_time. > > Like you said, irq_time is in dozens-of-microseconds. In VMs, as all > devices seen are virtual ones, irq_time seems to be not as desired > as it is in physical hosts. > > A quick (but not radical) solution may be: > disable CONFIG_IRQ_TIME_ACCOUNTING if CONFIG_PARAVIRT is selected. > Just adopt tick-based accounting: CONFIG_TICK_CPU_ACCOUNTING > > I am thinking what irq_time really *means* in VMs. That is not really an option for Linux distributions, which tend to run the same kernel image on the host and in the guest... -- All rights reversed