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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 2F577C54FCB for ; Wed, 22 Apr 2020 15:52:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F14B92076E for ; Wed, 22 Apr 2020 15:51:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587570720; bh=erYIPpCttlAKmVk7+ZuIu29yGQ+f83fJdaXrHXypskw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=FaAYR8hfX0yQ2l9T55EhjGpa1+B/Pm1gZacxe3d5DkEja/KQNud8cnyNcT3bDQFs/ KQ/uZdwz6g3pzPDjAKGCm9cH8GEowNwf7VqSJ4x7BSU4/AgcJybh99oyJJ6WfH1EWE fL+WYVKX9tIduE+tnWk6AnNB2yp++uEuptJ5fAVc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726811AbgDVPv7 (ORCPT ); Wed, 22 Apr 2020 11:51:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:57228 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726168AbgDVPv6 (ORCPT ); Wed, 22 Apr 2020 11:51:58 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7DFE620767; Wed, 22 Apr 2020 15:51:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587570718; bh=erYIPpCttlAKmVk7+ZuIu29yGQ+f83fJdaXrHXypskw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=eV+ic6cqswM4lN5NJv1zQbMoM/AXh3IbzYdwfvkGqAONMViojH7CxDYQ9wtGoyHLM iGSIP25KHmrOqCQNVHEJOhOpE+7obhFd5JbMZ3qkbsHPodNUtqLAyy4lL2lusUkAHY cQTyl672L9aXMPGUP6UWAH0epvHiEDnE6hSyhaHk= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 6002335203BC; Wed, 22 Apr 2020 08:51:58 -0700 (PDT) Date: Wed, 22 Apr 2020 08:51:58 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, rostedt@goodmis.org, qais.yousef@arm.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de Subject: Re: [PATCH 20/23] sched,rcutorture: Convert to sched_set_fifo_low() Message-ID: <20200422155158.GV17661@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20200422112719.826676174@infradead.org> <20200422112832.403795265@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200422112832.403795265@infradead.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 22, 2020 at 01:27:39PM +0200, Peter Zijlstra wrote: > Because SCHED_FIFO is a broken scheduler model (see previous patches) > take away the priority field, the kernel can't possibly make an > informed decision. > > Effectively no change. > > Cc: paulmck@kernel.org > Signed-off-by: Peter Zijlstra (Intel) > Reviewed-by: Ingo Molnar Reviewed-by: Paul E. McKenney > --- > kernel/rcu/rcutorture.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > --- a/kernel/rcu/rcutorture.c > +++ b/kernel/rcu/rcutorture.c > @@ -802,13 +802,11 @@ static int rcu_torture_boost(void *arg) > unsigned long endtime; > unsigned long oldstarttime; > struct rcu_boost_inflight rbi = { .inflight = 0 }; > - struct sched_param sp; > > VERBOSE_TOROUT_STRING("rcu_torture_boost started"); > > /* Set real-time priority. */ > - sp.sched_priority = 1; > - if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) { > + if (sched_set_fifo_low(current) < 0) { > VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!"); > n_rcu_torture_boost_rterror++; > } > >