From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757922Ab3BSBUX (ORCPT ); Mon, 18 Feb 2013 20:20:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:8202 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752087Ab3BSBUW (ORCPT ); Mon, 18 Feb 2013 20:20:22 -0500 Date: Mon, 18 Feb 2013 22:11:04 -0300 From: Marcelo Tosatti To: Frederic Weisbecker Cc: Michael Wolf , linux-kernel@vger.kernel.org, riel@redhat.com, gleb@redhat.com, kvm@vger.kernel.org, peterz@infradead.org, glommer@parallels.com, mingo@redhat.com, anthony@codemonkey.ws Subject: Re: [PATCH 0/4] Alter steal-time reporting in the guest Message-ID: <20130219011104.GA5785@amt.cnet> References: <20130205214818.4615.12937.stgit@lambeau> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Mon, Feb 18, 2013 at 05:43:47PM +0100, Frederic Weisbecker wrote: > 2013/2/5 Michael Wolf : > > In the case of where you have a system that is running in a > > capped or overcommitted environment the user may see steal time > > being reported in accounting tools such as top or vmstat. This can > > cause confusion for the end user. > > Sorry, I'm no expert in this area. But I don't really understand what > is confusing for the end user here. I suppose that what is wanted is to subtract stolen time due to 'known reasons' from steal time reporting. 'Known reasons' being, for example, hard caps. So a vcpu executing instructions with no halt, but limited to 80% of available bandwidth, would not have 20% of stolen time reported. But yes, a description of the scenario that is being dealt with, with details, is important. > > To ease the confusion this patch set > > adds the idea of consigned (expected steal) time. The host will separate > > the consigned time from the steal time. Tthe steal time will only be altered > > if hard limits (cfs bandwidth control) is used. The period and the quota used > > to separate the consigned time (expected steal) from the steal time are taken > > from the cfs bandwidth control settings. Any other steal time accruing during > > that period will show as the traditional steal time. > > I'm also a bit confused here. steal time will then only account the > cpu time lost due to quotas from cfs bandwidth control? Also what do > you exactly mean by "expected steal time"? Is it steal time due to > overcommitting minus scheduler quotas? > > Thanks.