From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760060AbbBIJ1m (ORCPT ); Mon, 9 Feb 2015 04:27:42 -0500 Received: from casper.infradead.org ([85.118.1.10]:51542 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759819AbbBIJ1l (ORCPT ); Mon, 9 Feb 2015 04:27:41 -0500 Date: Mon, 9 Feb 2015 10:27:35 +0100 From: Peter Zijlstra To: huang ying Cc: Huang Ying , Ingo Molnar , LKML , LKP ML , "Wu, Fengguang" Subject: Re: [LKP] [sched/core] 9edfbfed3f5: +88.2% hackbench.time.involuntary_context_switches Message-ID: <20150209092735.GP5029@twins.programming.kicks-ass.net> References: <1423461513.5968.56.camel@intel.com> <20150209083120.GL5029@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 09, 2015 at 04:47:07PM +0800, huang ying wrote: > There are no distinguishable difference between the parent and the child > for hackbench throughput number. > > Usually you will not consider statistics such as involuntary context > switches? Only if there's a 'problem' with the primary performance metric (total runtime in case of hackbench). Once the primary metric shifts, you go look at what the cause of this change might be, at that point things like # context switches etc.. are interesting. As long as the primary performance metric is stable, meh. As such; I would suggest _always_ reporting the primary metric for each benchmark, preferably on top and not hidden somewhere in the mass of numbers. I now had to very carefully waste a few minutes of my time reading those numbers to see if there was anything useful in; there wasn't.