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=-5.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,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 B83D0C54FCB for ; Wed, 22 Apr 2020 13:27:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8AF03206EC for ; Wed, 22 Apr 2020 13:27:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=pobox.com header.i=@pobox.com header.b="f1uGHaxY"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=fluxnic.net header.i=@fluxnic.net header.b="hn3u61Fd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726719AbgDVN1M (ORCPT ); Wed, 22 Apr 2020 09:27:12 -0400 Received: from pb-smtp20.pobox.com ([173.228.157.52]:50511 "EHLO pb-smtp20.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726335AbgDVN1M (ORCPT ); Wed, 22 Apr 2020 09:27:12 -0400 Received: from pb-smtp20.pobox.com (unknown [127.0.0.1]) by pb-smtp20.pobox.com (Postfix) with ESMTP id C1B04C125B; Wed, 22 Apr 2020 09:27:09 -0400 (EDT) (envelope-from nico@fluxnic.net) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=date:from:to :cc:subject:in-reply-to:message-id:references:mime-version :content-type; s=sasl; bh=kctC3QbxGnNRnpH2Si8fA35MZxo=; b=f1uGHa xYMs/JRLH0ylPKDqOnCWo8/cs6yP7tng+BbGY4r68a70Ik9B6Pl44UbLqhVl2v0N 1SZKGzj91Rn9qebO7b2K1ov37WMmJOGZHL0OnusZNkMCKDojP2bit+Ndh/pLCQXn 2vAG/XE8PhwMBTLQbaoqpsEBcOGvDf7oefmgE= Received: from pb-smtp20.sea.icgroup.com (unknown [127.0.0.1]) by pb-smtp20.pobox.com (Postfix) with ESMTP id B93C8C125A; Wed, 22 Apr 2020 09:27:09 -0400 (EDT) (envelope-from nico@fluxnic.net) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed; d=fluxnic.net; h=date:from:to:cc:subject:in-reply-to:message-id:references:mime-version:content-type; s=2016-12.pbsmtp; bh=skQgCCgpMr7/68sSM5jIJAK8zQSZRKSb1HMqaNQoOjo=; b=hn3u61FdDFFZLIjJoumE7mFVdUyUX95jMkqfZ3tkQHVb/XMCUMeGSwYSpJaCjP46nZTop9XP+z+Ral1LYugCIZhj3fqwgTp0T08gplDKDPEbHTg0LrMJDITCep7h18FRL7B4caXI6+LGTBpJ1cYa7vYCh6XXMfryXVWfVZNvVZk= Received: from yoda.home (unknown [24.203.50.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp20.pobox.com (Postfix) with ESMTPSA id A14E8C1259; Wed, 22 Apr 2020 09:27:06 -0400 (EDT) (envelope-from nico@fluxnic.net) Received: from xanadu.home (xanadu.home [192.168.2.2]) by yoda.home (Postfix) with ESMTPSA id A72F72DA016E; Wed, 22 Apr 2020 09:27:04 -0400 (EDT) Date: Wed, 22 Apr 2020 09:27:04 -0400 (EDT) From: Nicolas Pitre 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, rmk+kernel@arm.linux.org.uk Subject: Re: [PATCH 02/23] sched,bL_switcher: Convert to sched_set_fifo*() In-Reply-To: <20200422112831.339113081@infradead.org> Message-ID: References: <20200422112719.826676174@infradead.org> <20200422112831.339113081@infradead.org> User-Agent: Alpine 2.21 (LFD 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Pobox-Relay-ID: F6189CE2-849C-11EA-ADF9-B0405B776F7B-78420484!pb-smtp20.pobox.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 22 Apr 2020, 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. > > In this case, use fifo_low, because it only cares about being above > SCHED_NORMAL. Effectively no change in behaviour. > > Cc: nico@fluxnic.net > Cc: rmk+kernel@arm.linux.org.uk > Signed-off-by: Peter Zijlstra (Intel) > Reviewed-by: Ingo Molnar Acked-by: Nicolas Pitre > --- > arch/arm/common/bL_switcher.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > --- a/arch/arm/common/bL_switcher.c > +++ b/arch/arm/common/bL_switcher.c > @@ -270,12 +270,11 @@ static struct bL_thread bL_threads[NR_CP > static int bL_switcher_thread(void *arg) > { > struct bL_thread *t = arg; > - struct sched_param param = { .sched_priority = 1 }; > int cluster; > bL_switch_completion_handler completer; > void *completer_cookie; > > - sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m); > + sched_set_fifo_low(current); > complete(&t->started); > > do { > > >