Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933432AbcKGSaw (ORCPT ); Mon, 7 Nov 2016 13:30:52 -0500 Received: from smtprelay0126.hostedemail.com ([216.40.44.126]:40729 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932846AbcKGSau (ORCPT ); Mon, 7 Nov 2016 13:30:50 -0500 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1539:1593:1594:1711:1730:1747:1777:1792:2194:2199:2393:2553:2559:2562:2693:2898:3138:3139:3140:3141:3142:3352:3622:3865:3867:3872:3874:5007:6119:6261:7875:7903:10004:10400:10450:10455:10848:10967:11232:11658:11914:12296:12663:12740:12760:13069:13311:13357:13439:14096:14097:14181:14659:14721:19904:19999:21080:30054:30070:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:5,LUA_SUMMARY:none X-HE-Tag: club90_4121ae6163614 X-Filterd-Recvd-Size: 1825 Date: Mon, 7 Nov 2016 13:30:46 -0500 From: Steven Rostedt To: Clark Williams Cc: Daniel Bristot de Oliveira , Ingo Molnar , Peter Zijlstra , Christoph Lameter , linux-rt-users , LKML Subject: Re: [PATCH] sched/rt: RT_RUNTIME_GREED sched feature Message-ID: <20161107133046.7e4458c1@gandalf.local.home> In-Reply-To: <20161107122221.299d026a@tagon> References: <20161107122221.299d026a@tagon> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 756 Lines: 18 On Mon, 7 Nov 2016 12:22:21 -0600 Clark Williams wrote: > I'm still reviewing the patch, but I have to wonder why bother with making it a scheduler feature? > > The SCHED_FIFO definition allows a fifo thread to starve others > because a fifo task will run until it yields. Throttling was added as > a safety valve to allow starved SCHED_OTHER tasks to get some cpu > time. Adding this unconditionally gets us a safety valve for > throttling a badly written fifo task, but allows the fifo task to > continue to consume cpu cycles if it's not starving anyone. > > Or am I missing something that's blazingly obvious? Or I say make it the default. If people want the old behavior, they can modify SCHED_FEATURES to do so. -- Steve