Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935099Ab3FSUe2 (ORCPT ); Wed, 19 Jun 2013 16:34:28 -0400 Received: from mail-pb0-f49.google.com ([209.85.160.49]:41813 "EHLO mail-pb0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934714Ab3FSUe0 (ORCPT ); Wed, 19 Jun 2013 16:34:26 -0400 From: Kevin Hilman To: Frederic Weisbecker Cc: linaro-kernel@lists.linaro.org, Ingo Molnar , Peter Zijlstra , Clark Williams , Tony Luck , Andrew Morton , Kees Cook , Mel Gorman , Rik van Riel , open list Subject: Re: [PATCH 1/2] sched/nohz: add sysctl control over sched_tick_max_deferment In-Reply-To: <20130619184238.GD21522@somewhere.redhat.com> (Frederic Weisbecker's message of "Wed, 19 Jun 2013 20:42:40 +0200") References: <1371599913-1232-1-git-send-email-khilman@linaro.org> <20130619184238.GD21522@somewhere.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) Date: Wed, 19 Jun 2013 13:34:23 -0700 Message-ID: <87ehbx6drk.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1425 Lines: 37 Frederic Weisbecker writes: > On Tue, Jun 18, 2013 at 04:58:28PM -0700, Kevin Hilman wrote: >> Allow sysctl override of sched_tick_max_deferment in order to ease >> finding/fixing the remaining issues with full nohz. >> >> The value to be written is in jiffies, and -1 means the max deferment >> is disabled (scheduler_tick_max_deferment() returns KTIME_MAX.) >> >> Cc: Frederic Weisbecker >> Signed-off-by: Kevin Hilman > > This looks like a useful thing but I wonder if a debugfs file would > be more appropriate than sysctl. > > The scheduler tick max deferment is supposed to be a temporary > hack so we probably don't want to bring a real user ABI for that. I wondered about that as well, but I wasn't sure if the existing knobs under CONFIG_SCHED_DEBUG (sched_min_granularity_ns, sched_latency_ns, etc.) are considered permanant ABI, or optional debugging tools. This new option is inside CONFIG_SCHED_DEBUG along with the others, but if debugfs is preferred I can move it there. It seems strange though to just have this knob in debugfs and the rest in sysctl under CONFIG_SCHED_DEBUG. Thanks, Kevin -- 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/