Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932827AbaD1QhA (ORCPT ); Mon, 28 Apr 2014 12:37:00 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:54323 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752665AbaD1Qgx (ORCPT ); Mon, 28 Apr 2014 12:36:53 -0400 Date: Mon, 28 Apr 2014 09:36:49 -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: <20140428163649.GD4430@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <5354BA85.6010003@intel.com> <20140422015958.GB4496@linux.vnet.ibm.com> <5355D6C8.7080200@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5355D6C8.7080200@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14042816-9332-0000-0000-000000A13B6A Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 22, 2014 at 10:41:12AM +0800, Jet Chen wrote: > On 04/22/2014 09:59 AM, Paul E. McKenney wrote: > >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? > > > Yes, you're right. OK, sounds like a bit of rework is in order, then... 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/