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[23.128.96.18]) by mx.google.com with ESMTP id ov7si5364166ejb.224.2020.07.02.02.28.37; Thu, 02 Jul 2020 02:29:01 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726555AbgGBJ22 (ORCPT + 99 others); Thu, 2 Jul 2020 05:28:28 -0400 Received: from foss.arm.com ([217.140.110.172]:58526 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726183AbgGBJ22 (ORCPT ); Thu, 2 Jul 2020 05:28:28 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7771331B; Thu, 2 Jul 2020 02:28:27 -0700 (PDT) Received: from [192.168.178.2] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B38553F71E; Thu, 2 Jul 2020 02:28:25 -0700 (PDT) Subject: Re: [PATCH] sched/fair: update_pick_idlest() Select group with lowest group_util when idle_cpus are equal To: Peter Puhov , Valentin Schneider Cc: linux-kernel@vger.kernel.org, Robert Foley , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Steven Rostedt , Ben Segall , Mel Gorman References: <20200616164801.18644-1-peter.puhov@linaro.org> From: Dietmar Eggemann Message-ID: <106350c5-c2b7-a63c-2b06-761f523ee67c@arm.com> Date: Thu, 2 Jul 2020 11:27:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/06/2020 16:52, Peter Puhov wrote: > On Wed, 17 Jun 2020 at 06:50, Valentin Schneider > wrote: >> >> >> On 16/06/20 17:48, peter.puhov@linaro.org wrote: >>> From: Peter Puhov >>> We tested this patch with following benchmarks: >>> perf bench -f simple sched pipe -l 4000000 >>> perf bench -f simple sched messaging -l 30000 >>> perf bench -f simple mem memset -s 3GB -l 15 -f default >>> perf bench -f simple futex wake -s -t 640 -w 1 >>> sysbench cpu --threads=8 --cpu-max-prime=10000 run >>> sysbench memory --memory-access-mode=rnd --threads=8 run >>> sysbench threads --threads=8 run >>> sysbench mutex --mutex-num=1 --threads=8 run >>> hackbench --loops 20000 >>> hackbench --pipe --threads --loops 20000 >>> hackbench --pipe --threads --loops 20000 --datasize 4096 >>> >>> and found some performance improvements in: >>> sysbench threads >>> sysbench mutex >>> perf bench futex wake >>> and no regressions in others. >>> >> >> One nitpick for the results of those: condensing them in a table form would >> make them more reader-friendly. Perhaps something like: >> >> | Benchmark | Metric | Lower is better? | BASELINE | SERIES | DELTA | >> |------------------+----------+------------------+----------+--------+-------| >> | Sysbench threads | # events | No | 45526 | 56567 | +24% | >> | Sysbench mutex | ... | | | | | >> >> If you want to include more stats for each benchmark, you could have one table >> per (e.g. see [1]) - it'd still be a more readable form (or so I believe). Wouldn't Unix Bench's 'execl' and 'spawn' be the ultimate test cases for those kind of changes? I only see minor improvements with tip/sched/core as base on hikey620 (Arm64 octa-core). base w/ patch ./Run spawn -c 8 -i 10 633.6 635.1 ./Run execl -c 8 -i 10 1187.5 1190.7 At the end of find_idlest_group(), when comparing local and idlest, it is explicitly mentioned that number of idle_cpus is used instead of utilization. The comparision between potential idle groups and local & idlest group should probably follow the same rules. I haven't tested it with https://lkml.kernel.org/r/20200624154422.29166-1-vincent.guittot@linaro.org which might have an influence here too.