From mboxrd@z Thu Jan 1 00:00:00 1970 From: khilman@kernel.org (Kevin Hilman) Date: Mon, 29 Sep 2014 08:11:25 -0700 Subject: [PATCH] sched/nohz: add debugfs control over sched_tick_max_deferment In-Reply-To: <20140927165938.GB21729@lerouge> (Frederic Weisbecker's message of "Sat, 27 Sep 2014 18:59:39 +0200") References: <1411760732-14102-1-git-send-email-khilman@kernel.org> <20140927165938.GB21729@lerouge> Message-ID: <7hh9zq31ia.fsf@deeprootsystems.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Frederic Weisbecker writes: > On Fri, Sep 26, 2014 at 12:45:32PM -0700, Kevin Hilman wrote: >> From: Kevin Hilman >> >> Allow debugfs 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 > > So, I'm worried that it becomes a hack that everybody uses to shutdown > the tick completely then nobody will come and fix the issue that prevents > from doing it properly. OK. > I seriously doubt this will be used for development purpose to help > fixing the real problem. Well, that's what I was using it for, until I was distracted by other tasks. > Quite the opposite. If developers want to do > testing, they can as well comment out the call to scheduler_max_tick_deferment(). OK, fair enough. Thanks, Kevin From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754210AbaI2PL3 (ORCPT ); Mon, 29 Sep 2014 11:11:29 -0400 Received: from mail.kernel.org ([198.145.19.201]:54386 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751913AbaI2PL1 (ORCPT ); Mon, 29 Sep 2014 11:11:27 -0400 From: Kevin Hilman To: Frederic Weisbecker Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linaro-kernel@lists.linaro.org Subject: Re: [PATCH] sched/nohz: add debugfs control over sched_tick_max_deferment References: <1411760732-14102-1-git-send-email-khilman@kernel.org> <20140927165938.GB21729@lerouge> Date: Mon, 29 Sep 2014 08:11:25 -0700 In-Reply-To: <20140927165938.GB21729@lerouge> (Frederic Weisbecker's message of "Sat, 27 Sep 2014 18:59:39 +0200") Message-ID: <7hh9zq31ia.fsf@deeprootsystems.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) 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 Frederic Weisbecker writes: > On Fri, Sep 26, 2014 at 12:45:32PM -0700, Kevin Hilman wrote: >> From: Kevin Hilman >> >> Allow debugfs 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 > > So, I'm worried that it becomes a hack that everybody uses to shutdown > the tick completely then nobody will come and fix the issue that prevents > from doing it properly. OK. > I seriously doubt this will be used for development purpose to help > fixing the real problem. Well, that's what I was using it for, until I was distracted by other tasks. > Quite the opposite. If developers want to do > testing, they can as well comment out the call to scheduler_max_tick_deferment(). OK, fair enough. Thanks, Kevin