Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 11 Jul 2002 21:28:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 11 Jul 2002 21:28:47 -0400 Received: from coffee.Psychology.McMaster.CA ([130.113.218.59]:12768 "EHLO coffee.psychology.mcmaster.ca") by vger.kernel.org with ESMTP id ; Thu, 11 Jul 2002 21:28:46 -0400 Date: Thu, 11 Jul 2002 21:37:39 -0400 (EDT) From: Mark Hahn X-X-Sender: To: Subject: Re: HZ, preferably as small as possible In-Reply-To: <1026435320.1178.362.camel@sinai> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1099 Lines: 26 > > > Why must HZ be the same as 'interrupts per second'? > > > > s/interrupts/scheduler calls/ > > Uh, HZ is not scheduler calls per second. > > Neither exactly is it interrupts per second, but _timer_ interrupts per > second. It is the frequency of the timer interrupt. is there really code which uses HZ which is not merely fiddling with jiffies? that is, HZ is merely "jiffies per second". there's no reason the timer (if any!) couldn't run faster than HZ, even at different ratios depending on power level. afaikt, jiffies has survived because there's a need for a moderately fast, strictly monotonically increasing clock. that doesn't imply that the periodic timer needs to run at HZ or even that such a clock exists (tickless). just that the kernel promises to update jiffies at HZ, even if that means HZ is 1M, and goes by jumps of 10K. - 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/