Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263109AbVD3BK6 (ORCPT ); Fri, 29 Apr 2005 21:10:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263110AbVD3BK6 (ORCPT ); Fri, 29 Apr 2005 21:10:58 -0400 Received: from fsmlabs.com ([168.103.115.128]:35798 "EHLO fsmlabs.com") by vger.kernel.org with ESMTP id S263109AbVD3BKx (ORCPT ); Fri, 29 Apr 2005 21:10:53 -0400 Date: Fri, 29 Apr 2005 19:13:20 -0600 (MDT) From: Zwane Mwaikambo To: Venkatesh Pallipadi cc: Andrew Morton , Linus Torvalds , mingo@elte.hu, linux-kernel , Rajesh Shah , John Stultz , Andi Kleen , Asit K Mallick Subject: Re: [RFC][PATCH] i386 x86-64 Eliminate Local APIC timer interrupt In-Reply-To: <20050429172605.A23722@unix-os.sc.intel.com> Message-ID: References: <20050429172605.A23722@unix-os.sc.intel.com> 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: 1310 Lines: 27 On Fri, 29 Apr 2005, Venkatesh Pallipadi wrote: > Proposed Fix: > Attached is a prototype patch, that tries to eliminate the dependency on > local APIC timer for update_process_times(). The patch gets rid of Local APIC > timer altogether. We use the timer interrupt (IRQ 0) configured in > broadcast mode in IOAPIC instead (Doesn't work with 8259). > As changing anything related to basic timer interrupt is a little bit risky, > I have a boot parameter currently ("useapictimer") to switch back to original > local APIC timer way of doing things. I'm rather reluctant to advocate the broadcast scheme as i can see it breaking on a lot of systems, e.g. SMP systems which use i8259 (as you noted), IBM x440 and ES7000. If anything the default mode should be APIC timer and have a parameter to disable it. Regarding things like variable timer ticks, reprogramming the PIT is slow, and using it extensively for such sounds like a step in the wrong direction. Is this feature/bug going to proliferate amongst newer processor local APICs? Thanks, Zwane - 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/