From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 973E2C43381 for ; Tue, 12 Mar 2019 15:50:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C7D920693 for ; Tue, 12 Mar 2019 15:50:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726629AbfCLPuu (ORCPT ); Tue, 12 Mar 2019 11:50:50 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:44562 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726255AbfCLPuu (ORCPT ); Tue, 12 Mar 2019 11:50:50 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6FFE4165C; Tue, 12 Mar 2019 08:50:49 -0700 (PDT) Received: from e110439-lin (e110439-lin.cambridge.arm.com [10.1.194.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7B4103F71D; Tue, 12 Mar 2019 08:50:46 -0700 (PDT) Date: Tue, 12 Mar 2019 15:50:43 +0000 From: Patrick Bellasi To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-api@vger.kernel.org, Ingo Molnar , Tejun Heo , "Rafael J . Wysocki" , Vincent Guittot , Viresh Kumar , Paul Turner , Quentin Perret , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan Subject: Re: [PATCH v7 01/15] sched/core: uclamp: Add CPU's clamp buckets refcounting Message-ID: <20190312155043.vj3fiutnsovjti2x@e110439-lin> References: <20190208100554.32196-1-patrick.bellasi@arm.com> <20190208100554.32196-2-patrick.bellasi@arm.com> <20190312152059.GA5922@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190312152059.GA5922@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12-Mar 16:20, Peter Zijlstra wrote: > On Fri, Feb 08, 2019 at 10:05:40AM +0000, Patrick Bellasi wrote: > > +/* Integer ceil-rounded range for each bucket */ > > +#define UCLAMP_BUCKET_DELTA ((SCHED_CAPACITY_SCALE / UCLAMP_BUCKETS) + 1) > > Uhm, should that not me ((x+y-1)/y), aka. DIV_ROUND_UP(x,y) ? Well, there is certainly some rounding to be done... > The above would give 4 for 9/3, which is clearly buggered. .. still the math above should work fine within the boundaries we define for UCLAMP_BUCKET_DELTA (5..20 groups) and considering that SCHED_CAPACITY_SCALE will never be smaller then 1024. The above is designed to shrink the topmost bucket wrt all the others but it will never be smaller than ~30%. Here are the start values computed for each bucket using the math above and the computed shrinking percentage for the topmost bucket: bukets size: 205, top bucket start@820 (err: 0.49%), buckets: {0: 0, 1: 205, 2: 410, 3: 615, 4: 820} bukets size: 171, top bucket start@855 (err: 1.17%), buckets: {0: 0, 1: 171, 2: 342, 3: 513, 4: 684, 5: 855} bukets size: 147, top bucket start@882 (err: 3.40%), buckets: {0: 0, 1: 147, 2: 294, 3: 441, 4: 588, 5: 735, 6: 882} bukets size: 129, top bucket start@903 (err: 6.20%), buckets: {0: 0, 1: 129, 2: 258, 3: 387, 4: 516, 5: 645, 6: 774, 7: 903} bukets size: 114, top bucket start@912 (err: 1.75%), buckets: {0: 0, 1: 114, 2: 228, 3: 342, 4: 456, 5: 570, 6: 684, 7: 798, 8: 912} bukets size: 103, top bucket start@927 (err: 5.83%), buckets: {0: 0, 1: 103, 2: 206, 3: 309, 4: 412, 5: 515, 6: 618, 7: 721, 8: 824, 9: 927} bukets size: 94, top bucket start@940 (err: 10.64%), buckets: {0: 0, 1: 94, 2: 188, 3: 282, 4: 376, 5: 470, 6: 564, 7: 658, 8: 752, 9: 846, 10: 940} bukets size: 86, top bucket start@946 (err: 9.30%), buckets: {0: 0, 1: 86, 2: 172, 3: 258, 4: 344, 5: 430, 6: 516, 7: 602, 8: 688, 9: 774, 10: 860, 11: 946} bukets size: 79, top bucket start@948 (err: 3.80%), buckets: {0: 0, 1: 79, 2: 158, 3: 237, 4: 316, 5: 395, 6: 474, 7: 553, 8: 632, 9: 711, 10: 790, 11: 869, 12: 948} bukets size: 74, top bucket start@962 (err: 16.22%), buckets: {0: 0, 1: 74, 2: 148, 3: 222, 4: 296, 5: 370, 6: 444, 7: 518, 8: 592, 9: 666, 10: 740, 11: 814, 12: 888, 13: 962} bukets size: 69, top bucket start@966 (err: 15.94%), buckets: {0: 0, 1: 69, 2: 138, 3: 207, 4: 276, 5: 345, 6: 414, 7: 483, 8: 552, 9: 621, 10: 690, 11: 759, 12: 828, 13: 897, 14: 966} bukets size: 65, top bucket start@975 (err: 24.62%), buckets: {0: 0, 1: 65, 2: 130, 3: 195, 4: 260, 5: 325, 6: 390, 7: 455, 8: 520, 9: 585, 10: 650, 11: 715, 12: 780, 13: 845, 14: 910, 15: 975} bukets size: 61, top bucket start@976 (err: 21.31%), buckets: {0: 0, 1: 61, 2: 122, 3: 183, 4: 244, 5: 305, 6: 366, 7: 427, 8: 488, 9: 549, 10: 610, 11: 671, 12: 732, 13: 793, 14: 854, 15: 915, 16: 976} bukets size: 57, top bucket start@969 (err: 3.51%), buckets: {0: 0, 1: 57, 2: 114, 3: 171, 4: 228, 5: 285, 6: 342, 7: 399, 8: 456, 9: 513, 10: 570, 11: 627, 12: 684, 13: 741, 14: 798, 15: 855, 16: 912, 17: 969} bukets size: 54, top bucket start@972 (err: 3.70%), buckets: {0: 0, 1: 54, 2: 108, 3: 162, 4: 216, 5: 270, 6: 324, 7: 378, 8: 432, 9: 486, 10: 540, 11: 594, 12: 648, 13: 702, 14: 756, 15: 810, 16: 864, 17: 918, 18: 972} bukets size: 52, top bucket start@988 (err: 30.77%), buckets: {0: 0, 1: 52, 2: 104, 3: 156, 4: 208, 5: 260, 6: 312, 7: 364, 8: 416, 9: 468, 10: 520, 11: 572, 12: 624, 13: 676, 14: 728, 15: 780, 16: 832, 17: 884, 18: 936, 19: 988} Does that makes sense? -- #include Patrick Bellasi