Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932134AbbLBMxr (ORCPT ); Wed, 2 Dec 2015 07:53:47 -0500 Received: from casper.infradead.org ([85.118.1.10]:54358 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756218AbbLBMxp (ORCPT ); Wed, 2 Dec 2015 07:53:45 -0500 Date: Wed, 2 Dec 2015 13:53:39 +0100 From: Peter Zijlstra To: Frederic Weisbecker Cc: LKML , Chris Metcalf , Thomas Gleixner , Luiz Capitulino , Christoph Lameter , Ingo Molnar , Viresh Kumar , Rik van Riel Subject: Re: [PATCH 4/7] sched: Account rr and fifo tasks separately Message-ID: <20151202125339.GE9928@worktop.ger.corp.intel.com> References: <1447424529-13671-1-git-send-email-fweisbec@gmail.com> <1447424529-13671-5-git-send-email-fweisbec@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1447424529-13671-5-git-send-email-fweisbec@gmail.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 870 Lines: 19 On Fri, Nov 13, 2015 at 03:22:06PM +0100, Frederic Weisbecker wrote: > In order to evaluate tick dependency, we need to account SCHED_RR and > SCHED_FIFO tasks separately as those policies don't have the same > preemption requirements. > > We still keep rt_nr_running as a cache to avoid additions between nr_rr > and nr_fifo all over the place. In which case you only need one of nr_fifo/nr_rr. Less accounting is better. Pick the one you need for the nohz_full condition, and leave the other. A quick look at sched_can_stop_tick() seems to suggest nr_rr is the interesting one. nr_rr < 2 should allow stopping the tick. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/