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,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 EF1CCC54FCB for ; Wed, 22 Apr 2020 15:51:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B87B820776 for ; Wed, 22 Apr 2020 15:51:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587570696; bh=VEUvieAw+qJQrUH6Ra5u2Y75NjpLr4K5DcKACRlBHJ0=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=lMJWGOJW34rZzqo2H5BTex9dKTxWDnzBW5POHDPS05d6PYlFtKIqWncab8zsb3iYm 0dIBPsI5G/unIsV3EetZWxyQBXbNo0JlDYJP4dIi1/f80m+z8hIj0MOhlhDISZUg/i naWkzRkjhirCoy3JlTzj3Bp1wLfm02XtKWU7y9kw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726661AbgDVPvg (ORCPT ); Wed, 22 Apr 2020 11:51:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:56976 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726183AbgDVPvf (ORCPT ); Wed, 22 Apr 2020 11:51:35 -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 360DE20767; Wed, 22 Apr 2020 15:51:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587570695; bh=VEUvieAw+qJQrUH6Ra5u2Y75NjpLr4K5DcKACRlBHJ0=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=Cz/zdu9yAgyUQye1V2xRKk4wKEUI7gelM7IBy7qa5KUIkDyHBveCOX5AvGzwZlueL qJqEgojLbmTBOBm0BAdm9PA9JyKCSblw0o1qdVxkiW37uNqSHCVglS0yiYGRRiR2qK +C3C2xrX5qk+as0A6NoIvsWkH3e9WgRAsv0Cv0MQ= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 12CAE35203BC; Wed, 22 Apr 2020 08:51:35 -0700 (PDT) Date: Wed, 22 Apr 2020 08:51:35 -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 18/23] sched,locktorture: Convert to sched_set_fifo() Message-ID: <20200422155135.GT17661@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20200422112719.826676174@infradead.org> <20200422112832.283981577@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200422112832.283981577@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 01:27:37PM +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 changes prio from 99 to 50. > > Cc: paulmck@kernel.org > Signed-off-by: Peter Zijlstra (Intel) > Reviewed-by: Ingo Molnar Reviewed-by: Paul E. McKenney > --- > kernel/locking/locktorture.c | 10 ++-------- > 1 file changed, 2 insertions(+), 8 deletions(-) > > --- a/kernel/locking/locktorture.c > +++ b/kernel/locking/locktorture.c > @@ -436,8 +436,6 @@ static int torture_rtmutex_lock(void) __ > > static void torture_rtmutex_boost(struct torture_random_state *trsp) > { > - int policy; > - struct sched_param param; > const unsigned int factor = 50000; /* yes, quite arbitrary */ > > if (!rt_task(current)) { > @@ -448,8 +446,7 @@ static void torture_rtmutex_boost(struct > */ > if (trsp && !(torture_random(trsp) % > (cxt.nrealwriters_stress * factor))) { > - policy = SCHED_FIFO; > - param.sched_priority = MAX_RT_PRIO - 1; > + sched_set_fifo(current); > } else /* common case, do nothing */ > return; > } else { > @@ -462,13 +459,10 @@ static void torture_rtmutex_boost(struct > */ > if (!trsp || !(torture_random(trsp) % > (cxt.nrealwriters_stress * factor * 2))) { > - policy = SCHED_NORMAL; > - param.sched_priority = 0; > + sched_set_normal(current, 0); > } else /* common case, do nothing */ > return; > } > - > - sched_setscheduler_nocheck(current, policy, ¶m); > } > > static void torture_rtmutex_delay(struct torture_random_state *trsp) > >