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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 7A735C55185 for ; Wed, 22 Apr 2020 11:39:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 515782082E for ; Wed, 22 Apr 2020 11:39:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="GPgGS/kF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726990AbgDVLjf (ORCPT ); Wed, 22 Apr 2020 07:39:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47388 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726261AbgDVLje (ORCPT ); Wed, 22 Apr 2020 07:39:34 -0400 Received: from merlin.infradead.org (unknown [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89870C03C1A8 for ; Wed, 22 Apr 2020 04:39:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=9ZYRrFubhKWBZR+DG11ZexWw9V1Lf4rMr1vskSDfSak=; b=GPgGS/kFC6XKQzNVPukF7TtJ4s I72GsodKHX3RxXma+WjL/SyZL7NWtr8ab7bnbTlPAGEv9zE4xf3Bhy0ttTXP0gd4UZL8Bsvy1T05m zrzJMSo40PKhcsZd7X2hSJAqWcuEwwiTaw8n1nIj05Y/fG7U85UIgbPxWmU9tcRaHcCFRSoGuD/6Y 8i2H2fqCqzuy6ZVPcH6MZT7b08XoZR4KwJprQxr1h2f6bLwirdrqMS0WUVgm8n6mjaGZQBfgWHhYE 1Tha3MlV7x3bK+zjCGiBZ7mJd3hP6PlwSpmgZVYyPvF9o8uLMupN8KL1Z3iuRBZeOKWtPV1Ofm+JP pU/RPSyA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jRDib-000753-4F; Wed, 22 Apr 2020 11:39:05 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id DF3BD306831; Wed, 22 Apr 2020 13:39:03 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C8C6F203AA838; Wed, 22 Apr 2020 13:39:03 +0200 (CEST) Date: Wed, 22 Apr 2020 13:39:03 +0200 From: Peter Zijlstra To: mingo@kernel.org, linux-kernel@vger.kernel.org Cc: 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 17/23] sched,irq: Convert to sched_set_fifo() Message-ID: <20200422113903.GB20730@hirez.programming.kicks-ass.net> References: <20200422112719.826676174@infradead.org> <20200422112832.224090625@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200422112832.224090625@infradead.org> 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 01:27:36PM +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. That's ofcourse a flat out lie; I wrote this before I noticed that -1 thing. It most definitely changes that. I also only noticed this while reading through my own copy after sending :-/ > @@ -1281,13 +1278,12 @@ setup_irq_thread(struct irqaction *new, > } else { > t = kthread_create(irq_thread, new, "irq/%d-s-%s", irq, > new->name); > - param.sched_priority -= 1; > }