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 C6BF6C55185 for ; Wed, 22 Apr 2020 13:26:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 90BAD20787 for ; Wed, 22 Apr 2020 13:26:38 +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="v50UMiFf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726572AbgDVN0h (ORCPT ); Wed, 22 Apr 2020 09:26:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726046AbgDVN0h (ORCPT ); Wed, 22 Apr 2020 09:26:37 -0400 Received: from merlin.infradead.org (unknown [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F3C45C03C1A9 for ; Wed, 22 Apr 2020 06:26:36 -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=bduZ/9IMfziqIRTnhoBaYjslx+rtMD8dHnYkLXsa/Tc=; b=v50UMiFftdWzYsHHn1JilwsyVF 0nGoYo28zhxHKriaOQ/SiOYxOqGeT+yXtIfdpeU+mUOCbipC2vh+u1PKSwDaY1ehs5r/ya0+a4r0b wioy79gBZy0hvrSD9Uq8BBFVbguypGouZ9Acl471bTIVpOEudQfAoNDDpfZWAOuzJWWk6rLp+1zyb lFVzD4BNc9fg55faldXHtMU5Cv1/n0ElBiPsAWjrzGPraByxXGN57g+WH173Zv8SPgWuHjZ1/1prC LMr8bS2dgE67q6PvhBeY6LmQlU8kDs6e8/4NBi/hE3kgcfX9dPNyScu8NCvBjWPaF+wlvI8IriFet ju3pPYfw==; 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 1jRFOA-0000y5-7o; Wed, 22 Apr 2020 13:26:06 +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 D736D304CFD; Wed, 22 Apr 2020 15:26:04 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C80B8286A6E3B; Wed, 22 Apr 2020 15:26:04 +0200 (CEST) Date: Wed, 22 Apr 2020 15:26:04 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, qais.yousef@arm.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, hverkuil@xs4all.nl, awalls@md.metrocast.net Subject: Re: [PATCH 09/23] sched,ivtv: Convert to sched_set_fifo*() Message-ID: <20200422132604.GI20730@hirez.programming.kicks-ass.net> References: <20200422112719.826676174@infradead.org> <20200422112831.752048390@infradead.org> <20200422085345.48b50508@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200422085345.48b50508@gandalf.local.home> 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 08:53:45AM -0400, Steven Rostedt wrote: > On Wed, 22 Apr 2020 13:27:28 +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 from 99 to 50. > > I wonder for the 99 users, we should have a sched_set_high() that would set > the task to something like 75. > > That is, above default 50? No. If userspace knows, userspace can fix it. We must not bother with priority, simply because we cannot, possibly, say something useful.