Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753497AbaDVCAH (ORCPT ); Mon, 21 Apr 2014 22:00:07 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:53620 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751240AbaDVCAE (ORCPT ); Mon, 21 Apr 2014 22:00:04 -0400 Date: Mon, 21 Apr 2014 18:59:58 -0700 From: "Paul E. McKenney" To: Jet Chen Cc: LKML , lkp@01.org, Fengguang Wu Subject: Re: [sched,rcu] 9234566d3a3: +1.6% will-it-scale.scalability, +1302.6% time.involuntary_context_switches Message-ID: <20140422015958.GB4496@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <5354BA85.6010003@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5354BA85.6010003@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14042202-1542-0000-0000-0000013FA814 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 21, 2014 at 02:28:21PM +0800, Jet Chen wrote: > Hi Paul, > > we noticed the below changes on > git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git torture.2014.04.18a > commit 9234566d3a36c0aead8852e3c2ca94cd8ebfe219 ("sched,rcu: Make cond_resched() report RCU quiescent states") My impression of these statistics is that this commit results in huge numbers of additional context switches and interrupts, but has a slightly positive effect on performance and a larger negative effect on scalability. Is this a reasonable interpretation? Thanx, Paul > Comparison 1 - parent commit of 9234566d3a36c0aead8852e3c2ca94cd8ebfe219 vs 9234566d3a36c0aead8852e3c2ca94cd8ebfe219 > > e119454e74a852f 9234566d3a36c0aead8852e3c > --------------- ------------------------- > 1035948 ~ 0% +1.6% 1052990 ~ 0% TOTAL will-it-scale.per_thread_ops > 1271322 ~ 0% +1.8% 1294004 ~ 0% TOTAL will-it-scale.per_process_ops > 0.63 ~ 0% -5.2% 0.60 ~ 0% TOTAL will-it-scale.scalability > 22470 ~ 2% +1302.6% 315168 ~ 2% TOTAL time.involuntary_context_switches > 84265 ~ 5% +1047.1% 966581 ~ 1% TOTAL interrupts.IWI > 1828 ~44% +189.6% 5295 ~13% TOTAL time.voluntary_context_switches > 5337 ~ 1% +82.1% 9720 ~ 1% TOTAL vmstat.system.cs > 118599 ~ 0% -30.4% 82545 ~ 0% TOTAL interrupts.0:IO-APIC-edge.timer > 224021 ~ 4% +34.7% 301858 ~ 2% TOTAL interrupts.RES > 25148 ~ 0% +7.0% 26917 ~ 0% TOTAL vmstat.system.in > 7063439 ~ 0% -5.2% 6694536 ~ 0% TOTAL interrupts.LOC > 188866 ~ 0% -3.1% 183008 ~ 0% TOTAL interrupts.NMI > 188866 ~ 0% -3.1% 183008 ~ 0% TOTAL interrupts.PMI > 3720 ~ 0% -1.5% 3665 ~ 0% TOTAL time.system_time > 1215 ~ 0% -1.4% 1198 ~ 0% TOTAL time.percent_of_cpu_this_job_got > > > Comparison 2 - b84c4e08143c98dad4b4d139f08db0b98b0d3ec4 vs 9234566d3a36c0aead8852e3c2ca94cd8ebfe219 > > Fengguang has reported stats changes about b84c4e08143c98dad4b4d139f08db0b98b0d3ec4 to you days ago. > git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2014.04.14a > commit b84c4e08143c98dad4b4d139f08db0b98b0d3ec4 ("sched,rcu: Make cond_resched() report RCU quiescent states") > > Let's have a compare here. > > b84c4e08143c98d 9234566d3a36c0aead8852e3c > --------------- ------------------------- > 809309 ~ 0% -2.6% 788400 ~ 0% TOTAL will-it-scale.per_process_ops > 0.61 ~ 0% -1.9% 0.60 ~ 0% TOTAL will-it-scale.scalability > 434080 ~ 0% -1.5% 427643 ~ 0% TOTAL will-it-scale.per_thread_ops > 4 ~11% +1.2e+05% 5249 ~ 2% TOTAL interrupts.IWI > 607 ~ 7% +28.0% 778 ~14% TOTAL interrupts.47:PCI-MSI-edge.eth0 > 12349 ~ 2% -14.6% 10548 ~ 1% TOTAL interrupts.0:IO-APIC-edge.timer > 3078 ~ 3% +20.9% 3722 ~ 6% TOTAL interrupts.RES > > > Comparison 3 - parent commit of b84c4e08143c98dad4b4d139f08db0b98b0d3ec4 vs b84c4e08143c98dad4b4d139f08db0b98b0d3ec4 > > Duplicated with Fengguang's report. Help you to see these info in a page :) > > ad86a04266f9b49 b84c4e08143c98dad4b4d139f > --------------- ------------------------- > 676264 ~ 0% +3.3% 698461 ~ 0% TOTAL will-it-scale.per_thread_ops > 1174547 ~ 0% +3.0% 1209307 ~ 0% TOTAL will-it-scale.per_process_ops > 1.67 ~ 0% -2.3% 1.63 ~ 0% TOTAL will-it-scale.scalability > 10522 ~ 2% +921.2% 107463 ~ 1% TOTAL time.involuntary_context_switches > 77671 ~ 3% +67.0% 129688 ~ 3% TOTAL interrupts.RES > 99502 ~ 0% -27.8% 71813 ~ 0% TOTAL interrupts.0:IO-APIC-edge.timer > 2554 ~ 0% +49.1% 3809 ~ 1% TOTAL vmstat.system.cs > 11524 ~ 0% -2.3% 11259 ~ 0% TOTAL vmstat.system.in > 213 ~ 0% -4.3% 204 ~ 0% TOTAL time.system_time > 74 ~ 0% -4.1% 71 ~ 0% TOTAL time.percent_of_cpu_this_job_got > 3495099 ~ 0% -3.1% 3387173 ~ 0% TOTAL interrupts.LOC > > > > > Thanks, > Jet > > > > ./runtest.py open2 32 1 4 6 8 > > -- 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/