Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754493AbaADTCo (ORCPT ); Sat, 4 Jan 2014 14:02:44 -0500 Received: from merlin.infradead.org ([205.233.59.134]:35851 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753367AbaADTCn (ORCPT ); Sat, 4 Jan 2014 14:02:43 -0500 Date: Sat, 4 Jan 2014 20:02:28 +0100 From: Peter Zijlstra To: fengguang.wu@intel.com Cc: Stephane Eranian , Ingo Molnar , LKML , lkp@linux.intel.com Subject: Re: perf-stat changes after "Use hrtimers for event multiplexing" Message-ID: <20140104190228.GG16438@laptop.programming.kicks-ass.net> References: <20140102061242.GB29352@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140102061242.GB29352@localhost> 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 Content-Length: 4093 Lines: 66 On Thu, Jan 02, 2014 at 02:12:42PM +0800, fengguang.wu@intel.com wrote: > Greetings, > > We noticed many perf-stat changes between commit 9e6302056f ("perf: Use > hrtimers for event multiplexing") and its parent commit ab573844e. > Are these expected changes? > > ab573844e3058ee 9e6302056f8029f438e853432 > --------------- ------------------------- > 152917 +842.9% 1441897 TOTAL interrupts.0:IO-APIC-edge.timer > 545996 +478.0% 3155637 TOTAL interrupts.LOC > 182281 +12.3% 204718 TOTAL softirqs.SCHED > 1.986e+08 -96.4% 7105919 TOTAL perf-stat.node-store-misses > 107241719 -99.7% 317525 TOTAL perf-stat.node-prefetch-misses > 1.938e+08 -90.7% 17930426 TOTAL perf-stat.node-load-misses > 2590 +247.8% 9009 TOTAL vmstat.system.in > 4.549e+12 +158.3% 1.175e+13 TOTAL perf-stat.stalled-cycles-backend > 6.807e+12 +149.1% 1.696e+13 TOTAL perf-stat.stalled-cycles-frontend > 1.753e+08 -50.8% 86339289 TOTAL perf-stat.node-prefetches > 8.326e+11 +45.0% 1.207e+12 TOTAL perf-stat.cpu-cycles > 37932143 +32.2% 50146025 TOTAL perf-stat.iTLB-load-misses > 4.738e+11 +30.1% 6.165e+11 TOTAL perf-stat.iTLB-loads > 2.56e+11 +30.1% 3.33e+11 TOTAL perf-stat.L1-icache-loads > 4.951e+11 +24.6% 6.169e+11 TOTAL perf-stat.instructions > 7.85e+08 +7.5% 8.439e+08 TOTAL perf-stat.LLC-prefetch-misses > 1.891e+12 +22.8% 2.322e+12 TOTAL perf-stat.ref-cycles > 4.344e+08 -20.3% 3.462e+08 TOTAL perf-stat.node-loads > 2.836e+11 +17.4% 3.328e+11 TOTAL perf-stat.branch-loads > 9.506e+10 +24.5% 1.183e+11 TOTAL perf-stat.branch-load-misses > 2.803e+11 +18.4% 3.319e+11 TOTAL perf-stat.branch-instructions > 7.988e+10 +20.9% 9.658e+10 TOTAL perf-stat.bus-cycles > 2.041e+09 +22.2% 2.495e+09 TOTAL perf-stat.branch-misses > 229145 -17.3% 189601 TOTAL perf-stat.cpu-migrations > 1.782e+11 +17.9% 2.1e+11 TOTAL perf-stat.dTLB-loads > 4.702e+08 -14.8% 4.006e+08 TOTAL perf-stat.LLC-load-misses > 1.418e+11 +17.4% 1.666e+11 TOTAL perf-stat.L1-dcache-loads > 1.838e+09 +16.1% 2.133e+09 TOTAL perf-stat.LLC-stores > 2.428e+09 +11.3% 2.702e+09 TOTAL perf-stat.LLC-loads > 2.788e+11 +8.6% 3.029e+11 TOTAL perf-stat.dTLB-stores > 8.66e+08 +10.8% 9.594e+08 TOTAL perf-stat.LLC-prefetches > 1.117e+09 +10.5% 1.234e+09 TOTAL perf-stat.dTLB-store-misses > 1.705e+09 +5.3% 1.796e+09 TOTAL perf-stat.L1-dcache-store-misses > 5.671e+09 +6.1% 6.015e+09 TOTAL perf-stat.L1-dcache-load-misses > 8.794e+10 +3.6% 9.109e+10 TOTAL perf-stat.L1-dcache-stores > 3.46e+09 +4.6% 3.618e+09 TOTAL perf-stat.cache-references > 8.696e+08 +1.8% 8.849e+08 TOTAL perf-stat.cache-misses > 1613129 +2.6% 1655724 TOTAL perf-stat.context-switches > > All of the changes happen in one of our test box, which has a DX58SO > baseboard and 4-core CPU. The boot dmesg and kconfig are attached. > We can test more boxes if necessary. How do you run perf stat? Curious that you notice this now, its a fairly old commit. IIRC we did have a few wobbles with that, but I cannot remember much detail. The biggest difference between before and after that patch is that we'd rotate while the core is 'idle'. So if you do something like 'perf stat -a' and have significant idle time it does indeed make a difference. -- 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/