Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758531Ab3GPBKe (ORCPT ); Mon, 15 Jul 2013 21:10:34 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:48804 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755419Ab3GPBKd (ORCPT ); Mon, 15 Jul 2013 21:10:33 -0400 Date: Tue, 16 Jul 2013 03:10:29 +0200 From: Frederic Weisbecker To: Steven Rostedt Cc: Dave Jones , Linux Kernel Mailing List Subject: Re: nohz: Warn if the machine can not perform nohz_full Message-ID: <20130716011028.GE13562@somewhere> References: <20130715170859.GA25570@redhat.com> <20130715171800.GD6442@somewhere> <20130715172423.GA27745@redhat.com> <20130715173848.GA1066@redhat.com> <1373914182.17876.165.camel@gandalf.local.home> <20130715185624.GB1706@redhat.com> <1373916620.17876.182.camel@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1373916620.17876.182.camel@gandalf.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1995 Lines: 48 On Mon, Jul 15, 2013 at 03:30:20PM -0400, Steven Rostedt wrote: > On Mon, 2013-07-15 at 14:56 -0400, Dave Jones wrote: > > On Mon, Jul 15, 2013 at 02:49:42PM -0400, Steven Rostedt wrote: > > > > Is a printk not enough for that purpose ? Tainting the kernel is kinda anti-social. > > > > printk's don't usually get peoples attention. Taints and warnings do. If > the hardware doesn't allow for nohz-full, and the only way to enable it > is via kernel command line, how do you scream to the user that it isn't > going to work. > > We could do a large banner saying: > > *************************************************************** > *************************************************************** > *************************************************************** > *************************************************************** > *** UNSTABLE TSC *** > *** NO_HZ_FULL disabled *** > *************************************************************** > *************************************************************** > *************************************************************** > *************************************************************** May be we can try that. In fact I have a pending patch that converts the stacktrace warning to a one line printk message, as Ingo reported that issue to me. But the risk is that it can be indeed lost in the flow. > > > And not do the warning. Maybe that will get peoples attentions? > > But then again, this could be lost in the boot up if the box prints a > lot of data. Well the above example is unlikely to be missed. If it is, then I believe a traditional warning would be lost as well. > > -- Steve > > -- 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/