Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760110AbZCPSLp (ORCPT ); Mon, 16 Mar 2009 14:11:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752244AbZCPSLf (ORCPT ); Mon, 16 Mar 2009 14:11:35 -0400 Received: from sovereign.computergmbh.de ([85.214.69.204]:43573 "EHLO sovereign.computergmbh.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752732AbZCPSLf (ORCPT ); Mon, 16 Mar 2009 14:11:35 -0400 Date: Mon, 16 Mar 2009 19:11:32 +0100 (CET) From: Jan Engelhardt To: Peter Zijlstra cc: Arjan van de Ven , Linux Kernel Mailing List Subject: Re: System tick rate In-Reply-To: <1236934167.5188.195.camel@laptop> Message-ID: References: <20090312072110.0a325543@infradead.org> <1236934167.5188.195.camel@laptop> User-Agent: Alpine 2.00 (LSU 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1407 Lines: 31 On Friday 2009-03-13 09:49, Peter Zijlstra wrote: >On Thu, 2009-03-12 at 15:45 +0100, Jan Engelhardt wrote: >> On Thursday 2009-03-12 15:21, Arjan van de Ven wrote: >> >On Thu, 12 Mar 2009 14:38:19 +0100 (CET) Jan Engelhardt wrote: >> >> >> >> is there an "official" way of obtaining the current tick rate when >> >> CONFIG_NO_HZ? >> > >> >what does "current tick rate" mean for you in a no-hz situation ? >> >is it the HZ value (which is supposed to be invisible from userspace, >> >so good luck) or the wakeup count ? >> >> Hm, I guess what I want is the number of timer interrupts which >> occurred within the observation period that called the scheduler >> code. (So that excludes RTC on usual x86en.) > >There is no tick rate with NO_HZ mode, only a max tick rate, but as >Arjan said, not even that is exposed to user-space. > >I think Dave's Niagra has the crown here, because he ran into some bug >in the NO_HZ code some while back because he idled longer than we ever >seen before. I think it was in the order of 30 minutes or something >without a single wakeup of the CPU. > Well if it idled that long, it surely did not run any processes, did it? -- 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/