From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263359AbVGOSFZ (ORCPT ); Fri, 15 Jul 2005 14:05:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263353AbVGOSFN (ORCPT ); Fri, 15 Jul 2005 14:05:13 -0400 Received: from fmr23.intel.com ([143.183.121.15]:59295 "EHLO scsfmr003.sc.intel.com") by vger.kernel.org with ESMTP id S263355AbVGOSCz (ORCPT ); Fri, 15 Jul 2005 14:02:55 -0400 Date: Fri, 15 Jul 2005 11:01:57 -0700 From: Venkatesh Pallipadi To: "Maciej W. Rozycki" Cc: Venkatesh Pallipadi , Andi Kleen , "Brown, Len" , akpm@osdl.org, linux-kernel@vger.kernel.org, torvalds@osdl.org, vojtech@suse.cz, christoph@lameter.com Subject: Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt Message-ID: <20050715110157.A16008@unix-os.sc.intel.com> References: <20050715102349.A15791@unix-os.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: ; from macro@linux-mips.org on Fri, Jul 15, 2005 at 06:54:30PM +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 15, 2005 at 06:54:30PM +0100, Maciej W. Rozycki wrote: > On Fri, 15 Jul 2005, Venkatesh Pallipadi wrote: > > > I wouldn't say it is totally impossible. There are ways in which Linux can work > > without a reliable Local APIC timer. One option being - make one CPU that gets > > the external timer interrupt multicast an IPI to all the other CPUs that > > wants to get periodic timer interrupt. > > That's like scratching your left ear with your right hand -- broadcasting > that external timer interrupt in the first place is more straightforward. > If you want to exclude CPUs from the list of receivers, just use the > logical destination mode appropriately. > Well.. I tried a patch to do the broadcast thing couple of months ago and failed to convince everyone :(. Further, it doesn't work well if you want to exclude some CPUs from the list of recievers. Logical destination is simple only for less than 8 CPUs. Beyond that with clustered or physical configuration it is difficult. Thanks, Venki