From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 1 Aug 2001 16:34:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 1 Aug 2001 16:34:01 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:60655 "EHLO hermes.mvista.com") by vger.kernel.org with ESMTP id ; Wed, 1 Aug 2001 16:33:44 -0400 Message-ID: <3B68678C.5B7BD150@mvista.com> Date: Wed, 01 Aug 2001 13:33:16 -0700 From: george anzinger Organization: Monta Vista Software X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.2.12-20b i686) X-Accept-Language: en MIME-Version: 1.0 To: root@chaos.analogic.com CC: Chris Friesen , linux-kernel@vger.kernel.org Subject: Re: No 100 HZ timer ! In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org "Richard B. Johnson" wrote: > > > george anzinger wrote: > > > > > The testing I have done seems to indicate a lower overhead on a lightly > > > loaded system, about the same overhead with some load, and much more > > > overhead with a heavy load. To me this seems like the wrong thing to > > > > Doesn't the "tick-less" system presume that somebody, somewhere, will > be sleeping sometime during the 1/HZ interval so that the scheduler > gets control? > > If everybody's doing: > > for(;;) > number_crunch(); > > And no I/O is pending, how does the jiffy count get bumped? Who cares if it gets bumped? In the tick less system the jiffy counter is a function. Thus, if you need it, it will be current, more current than in the ticked system because it is calculated on the spot and does not rely on an interrupt to "bump" it. > > I think the "tick-less" system relies upon a side-effect of > interactive use that can't be relied upon for design criteria. > Look at the code. You will find it here: http://sourceforge.net/projects/high-res-timers George