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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0BB8C433FE for ; Thu, 28 Oct 2021 21:36:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 96D9F60FE3 for ; Thu, 28 Oct 2021 21:36:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231387AbhJ1Vii (ORCPT ); Thu, 28 Oct 2021 17:38:38 -0400 Received: from mga02.intel.com ([134.134.136.20]:7162 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230522AbhJ1Vig (ORCPT ); Thu, 28 Oct 2021 17:38:36 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10151"; a="217704023" X-IronPort-AV: E=Sophos;i="5.87,191,1631602800"; d="scan'208";a="217704023" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Oct 2021 14:36:09 -0700 X-IronPort-AV: E=Sophos;i="5.87,191,1631602800"; d="scan'208";a="466289015" Received: from schen9-mobl.amr.corp.intel.com ([10.212.137.85]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Oct 2021 14:36:08 -0700 Message-ID: <8f6b4ab17a319117cbed8751aa4fa9f2d6e0ca5b.camel@linux.intel.com> Subject: Re: [PATCH v3 0/5] Improve newidle lb cost tracking and early abort From: Tim Chen To: Vincent Guittot Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, linux-kernel@vger.kernel.org Date: Thu, 28 Oct 2021 14:36:08 -0700 In-Reply-To: <20211028121530.GA19512@vingu-book> References: <20211019123537.17146-1-vincent.guittot@linaro.org> <7128695d64e9161637b67315b5beb51c4accdc82.camel@linux.intel.com> <720fd26424927dd27fea4e5719dafe8a0afaa8c4.camel@linux.intel.com> <20211028121530.GA19512@vingu-book> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2021-10-28 at 14:15 +0200, Vincent Guittot wrote: > > > It seems to make sense to skip the call > > to nohz_newidle_balance() for this case? > > nohz_newidle_balance() also tests this condition : > (this_rq->avg_idle < sysctl_sched_migration_cost) > and doesn't set NOHZ_NEWILB_KICKi in such case > > But this patch now used the condition : > this_rq->avg_idle < sd->max_newidle_lb_cost > and sd->max_newidle_lb_cost can be higher than > sysctl_sched_migration_cost > > which means that we can set NOHZ_NEWILB_KICK: > -although we decided to skip newidle loop > -or when we abort because this_rq->avg_idle < curr_cost + sd- > >max_newidle_lb_cost > > This is even more true when sysctl_sched_migration_cost is lowered > which is your case IIRC > > The patch below ensures that we don't set NOHZ_NEWILB_KICK in such > cases: > Thanks. Will ask our benchmark team to give it a spin. Tim