From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932160AbWIJNjR (ORCPT ); Sun, 10 Sep 2006 09:39:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932153AbWIJNjR (ORCPT ); Sun, 10 Sep 2006 09:39:17 -0400 Received: from ns2.suse.de ([195.135.220.15]:32222 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S932160AbWIJNjR (ORCPT ); Sun, 10 Sep 2006 09:39:17 -0400 From: Andi Kleen To: "Dong Feng" Subject: Re: Timer Selection Date: Sun, 10 Sep 2006 15:51:11 +0200 User-Agent: KMail/1.9.1 Cc: "Jeremy Fitzhardinge" , linux-kernel@vger.kernel.org References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200609101551.11521.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sunday 10 September 2006 12:34, Dong Feng wrote: > In i386 architecture, there are five timers as candidates in the selection > of "cur_timer." I feel among the five only two types can be used as Kernel > base timer, HPET and PIT. Kernel base timer is the timer trigger > timer_interrupt() periodically. Namely, the timer installed on IRQ 0 in > i386 architecture. > > Is the above understanding correct? Particularly I want to confirm which > timers can be used as Kernel base timer. Only HPET and PIT can be interrupt 0 in the PC architecture (HPET only if the legacy option is available), but there is no reason the main timer handler cannot be driven from another interval timer (e.g. x86-64 offers the APIC timer as a option for this) -Andi