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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,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 C85C5C28CF6 for ; Sat, 28 Jul 2018 12:42:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 768FB20873 for ; Sat, 28 Jul 2018 12:42:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 768FB20873 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728701AbeG1ODF (ORCPT ); Sat, 28 Jul 2018 10:03:05 -0400 Received: from outbound-smtp10.blacknight.com ([46.22.139.15]:41396 "EHLO outbound-smtp10.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728115AbeG1ODF (ORCPT ); Sat, 28 Jul 2018 10:03:05 -0400 Received: from mail.blacknight.com (pemlinmail03.blacknight.ie [81.17.254.16]) by outbound-smtp10.blacknight.com (Postfix) with ESMTPS id 22F8E1C1D32 for ; Sat, 28 Jul 2018 13:36:40 +0100 (IST) Received: (qmail 16350 invoked from network); 28 Jul 2018 12:36:40 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[37.228.237.66]) by 81.17.254.9 with ESMTPSA (DHE-RSA-AES256-SHA encrypted, authenticated); 28 Jul 2018 12:36:39 -0000 Date: Sat, 28 Jul 2018 13:36:39 +0100 From: Mel Gorman To: Francisco Jerez Cc: Srinivas Pandruvada , lenb@kernel.org, rjw@rjwysocki.net, peterz@infradead.org, ggherdovich@suse.cz, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, juri.lelli@redhat.com, viresh.kumar@linaro.org, Chris Wilson , Tvrtko Ursulin , Joonas Lahtinen , Eero Tamminen Subject: Re: [PATCH 4/4] cpufreq: intel_pstate: enable boost for Skylake Xeon Message-ID: <20180728123639.7ckv3ljnei3urn6m@techsingularity.net> References: <20180605214242.62156-1-srinivas.pandruvada@linux.intel.com> <20180605214242.62156-5-srinivas.pandruvada@linux.intel.com> <87bmarhqk4.fsf@riseup.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <87bmarhqk4.fsf@riseup.net> User-Agent: NeoMutt/20170912 (1.9.0) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 27, 2018 at 10:34:03PM -0700, Francisco Jerez wrote: > Srinivas Pandruvada writes: > > > Enable HWP boost on Skylake server and workstations. > > > > Please revert this series, it led to significant energy usage and > graphics performance regressions [1]. The reasons are roughly the ones > we discussed by e-mail off-list last April: This causes the intel_pstate > driver to decrease the EPP to zero when the workload blocks on IO > frequently enough, which for the regressing benchmarks detailed in [1] > is a symptom of the workload being heavily IO-bound, which means they > won't benefit at all from the EPP boost since they aren't significantly > CPU-bound, and they will suffer a decrease in parallelism due to the > active CPU core using a larger fraction of the TDP in order to achieve > the same work, causing the GPU to have a lower power budget available, > leading to a decrease in system performance. It slices both ways. With the series, there are large boosts to performance on other workloads where a slight increase in power usage is acceptable in exchange for performance. For example, Single socket skylake running sqlite v4.17 41ab43c9 Min Trans 2580.85 ( 0.00%) 5401.58 ( 109.29%) Hmean Trans 2610.38 ( 0.00%) 5518.36 ( 111.40%) Stddev Trans 28.08 ( 0.00%) 208.90 (-644.02%) CoeffVar Trans 1.08 ( 0.00%) 3.78 (-251.57%) Max Trans 2648.02 ( 0.00%) 5992.74 ( 126.31%) BHmean-50 Trans 2629.78 ( 0.00%) 5643.81 ( 114.61%) BHmean-95 Trans 2620.38 ( 0.00%) 5538.32 ( 111.36%) BHmean-99 Trans 2620.38 ( 0.00%) 5538.32 ( 111.36%) That's over doubling the transactions per second for that workload. Two-socket skylake running dbench4 v4.17 41ab43c9 Amean 1 40.85 ( 0.00%) 14.97 ( 63.36%) Amean 2 42.31 ( 0.00%) 17.33 ( 59.04%) Amean 4 53.77 ( 0.00%) 27.85 ( 48.20%) Amean 8 68.86 ( 0.00%) 43.78 ( 36.42%) Amean 16 82.62 ( 0.00%) 56.51 ( 31.60%) Amean 32 135.80 ( 0.00%) 116.06 ( 14.54%) Amean 64 737.51 ( 0.00%) 701.00 ( 4.95%) Amean 512 14996.60 ( 0.00%) 14755.05 ( 1.61%) This is reporting the average latency of operations running dbench. The series over halves the latencies. There are many examples of basic workloads that benefit heavily from the series and while I accept it may not be universal, such as the case where the graphics card needs the power and not the CPU, a straight revert is not the answer. Without the series, HWP cripplies the CPU. -- Mel Gorman SUSE Labs