Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933704AbcKGSuN (ORCPT ); Mon, 7 Nov 2016 13:50:13 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33268 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932965AbcKGSuG (ORCPT ); Mon, 7 Nov 2016 13:50:06 -0500 Date: Mon, 7 Nov 2016 12:39:31 -0600 From: Clark Williams To: Steven Rostedt 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: <20161107123931.2ddccc4d@tagon> In-Reply-To: <20161107133046.7e4458c1@gandalf.local.home> References: <20161107122221.299d026a@tagon> <20161107133046.7e4458c1@gandalf.local.home> Organization: Red Hat, Inc MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; boundary="Sig_/J4Y6mqUDHSkBtz9hfHA/JqQ"; protocol="application/pgp-signature" X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 07 Nov 2016 18:39:33 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2008 Lines: 52 --Sig_/J4Y6mqUDHSkBtz9hfHA/JqQ Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Mon, 7 Nov 2016 13:30:46 -0500 Steven Rostedt wrote: > On Mon, 7 Nov 2016 12:22:21 -0600 > Clark Williams wrote: >=20 > > I'm still reviewing the patch, but I have to wonder why bother with mak= ing it a scheduler feature? > >=20 > > 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.=20 > >=20 > > Or am I missing something that's blazingly obvious? =20 >=20 > Or I say make it the default. If people want the old behavior, they can > modify SCHED_FEATURES to do so. >=20 Ok, I can see wanting the previous behavior.=20 Clark --Sig_/J4Y6mqUDHSkBtz9hfHA/JqQ Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJYIMpjAAoJEOI5asVwYXLr/lwQAI4CfDz8KmtY76rEytEyrVvr 0RcTGxYuyqZfTXq+PkFNWo50JIPL1EMvvxl60G12RfGLep8zJk2YU0jv24/XwguG EZKN2xbXveQbOUvb3cVVGQBVggxExXLA2DzNZjx2sTZk1c/yLJXNfLiM6oUavQrj wSBXpQOAf6wS1hIfabFLwsTJXjAco2gLEQok/ZFTcywhfrSxAUUcYSds2HYdBZJe JXDIWLeE6B+QuC9pj58noaYi/X4kLuqRfqKXENrKtWzg5W7tTsw9hVA3sI5Z5VoE O/d1WUy6CkJIprYBJeAJKozyBStq2Qoi6nxfVLCazhLcyGcdXIIkWzqYm1gsGf5u 8LmPfUEYiPCbx72z/nHa4uth/G1BOPbSwe+TC2Wu8VRFarB8Vzeik6AyP9+oh4I3 R28EKDPwtQgljSLsNsi4Aqhfo3mobTSwTiA/O+Y+lfcWR2d8nNiIAV0IYshNUIVo WHCqzgxDdupW+3riFNfZfTQMzRZ2sQxaVVZjLR2PndacBNzAf1A3BSs5WD2FTizC cprjAbh+qS7Ylx8bHM00tXq6CB9qlruClfCkppDfHuHbHDlBu9iyMSwwyXpKWZ/A 1HwHes24v68DFqEuLp7vf6TWxjw/JmwmMQKR0rNsoPfon/BX79ZP6C49aLnn9xNt u7i69QBg+4OFYJXGfxG0 =tATf -----END PGP SIGNATURE----- --Sig_/J4Y6mqUDHSkBtz9hfHA/JqQ--