From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751356AbeFDQGM (ORCPT ); Mon, 4 Jun 2018 12:06:12 -0400 Received: from foss.arm.com ([217.140.101.70]:45356 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751058AbeFDQGK (ORCPT ); Mon, 4 Jun 2018 12:06:10 -0400 From: Patrick Bellasi To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Joel Fernandes , Steve Muckle Subject: [PATCH 0/2] Improve estimated utilization of preempted FAIR tasks Date: Mon, 4 Jun 2018 17:05:58 +0100 Message-Id: <20180604160600.22052-1-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.15.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Here is a small series to improve the estimated utilization of fair tasks which are preempted by either another FAIR task of by tasks of an higher priority scheduling class (i.e. RT and DL). It can certainly be improved, but it has been already functionally tested and given the discussion going on on IRC and in this other thread: https://lkml.org/lkml/2018/5/25/410 1527253951-22709-1-git-send-email-vincent.guittot@linaro.org I wanted to anticipate a possible simple alternative/additional approach to improve CPU utilization tracking for CFS tasks. Thus, every comment and suggestion is more then welcome! The main reasons and the overall idea is explained by the second patch of this series. While the first patch is just a first step in the direction of having a more memory and run-time efficient implementation. The ultimate benefit of this series is to make the CFS class more robust in terms of its integration with the schedutil governor. Indeed, by better estimating the CPU bandwidth requirements for CFS tasks we can assert more accurately their bandwidth demands and be less sensitive to side effect, on PELT, generated by higher priority classes preempting CFS tasks, like the CFS util_avg decay. Cheers Patrick Patrick Bellasi (2): sched/fair: pelt: use u32 for util_avg sched/fair: util_est: add running_sum tracking include/linux/sched.h | 3 ++- kernel/sched/debug.c | 2 +- kernel/sched/fair.c | 33 ++++++++++++++++++++++++--------- 3 files changed, 27 insertions(+), 11 deletions(-) -- 2.15.1