Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752558Ab3CFQel (ORCPT ); Wed, 6 Mar 2013 11:34:41 -0500 Received: from e9.ny.us.ibm.com ([32.97.182.139]:34248 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751583Ab3CFQej (ORCPT ); Wed, 6 Mar 2013 11:34:39 -0500 Message-ID: <1362586990.6373.0.camel@lambeau> Subject: Re: [PATCH 0/4] Alter steal-time reporting in the guest From: Michael Wolf Reply-To: mjw@linux.vnet.ibm.com To: Frederic Weisbecker Cc: Marcelo Tosatti , 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 Date: Wed, 06 Mar 2013 10:23:10 -0600 In-Reply-To: References: <20130205214818.4615.12937.stgit@lambeau> <20130219011104.GA5785@amt.cnet> <1362514928.6267.16.camel@lambeau> Organization: IBM-LTC Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.2-0ubuntu0.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13030616-7182-0000-0000-000005AA85E8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2519 Lines: 51 On Wed, 2013-03-06 at 14:34 +0100, Frederic Weisbecker wrote: > 2013/3/5 Michael Wolf : > > Sorry for the delay in the response. I did not see the email > > right away. > > > > On Mon, 2013-02-18 at 22:11 -0300, Marcelo Tosatti wrote: > >> 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. > > > > Yes exactly and the end user many times did not set up the guest and is > > not aware of the capping. The end user is only aware of the performance > > level that they were told they would get with the guest. > > > >> > >> But yes, a description of the scenario that is being dealt with, with > >> details, is important. > > > > I will add more detail to the description next time I submit the > > patches. How about something like,"In a cloud environment the user of a > > kvm guest is not aware of the underlying hardware or how many other > > guests are running on it. The end user is only aware of a level of > > performance that they should see." or does that just muddy the picture > > more?? > > That alone is probably not enough. But yeah, make sure you clearly > state the difference between expected (caps, sched bandwidth...) and > unexpected (overcommitting, competing load...) stolen time. Then add a > practical example as you made above that explains why it matters to > make that distinction and why you want to report it. > Ok, I understand what you are requesting. I will make sure to add it to the description the next time I submit the patches. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/