Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261174AbVBDT26 (ORCPT ); Fri, 4 Feb 2005 14:28:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266480AbVBDT1v (ORCPT ); Fri, 4 Feb 2005 14:27:51 -0500 Received: from ylpvm01-ext.prodigy.net ([207.115.57.32]:9372 "EHLO ylpvm01.prodigy.net") by vger.kernel.org with ESMTP id S263371AbVBDT1f (ORCPT ); Fri, 4 Feb 2005 14:27:35 -0500 Date: Fri, 4 Feb 2005 11:24:57 -0800 From: Tony Lindgren To: Zwane Mwaikambo Cc: Pavel Machek , Benjamin Herrenschmidt , Arjan van de Ven , Martin Schwidefsky , Andrea Arcangeli , George Anzinger , Thomas Gleixner , john stultz , Lee Revell , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Dynamic tick, version 050127-1 Message-ID: <20050204192457.GB24544@atomide.com> References: <20050203030359.GL13984@atomide.com> <20050203105647.GA1369@elf.ucw.cz> <20050203164331.GE14325@atomide.com> <20050204051929.GO14325@atomide.com> <20050204171805.GF22444@atomide.com> <20050204174254.GG22444@atomide.com> <20050204185804.GA24544@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050204185804.GA24544@atomide.com> User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2058 Lines: 48 * Tony Lindgren [050204 11:14]: > * Zwane Mwaikambo [050204 09:54]: > > On Fri, 4 Feb 2005, Tony Lindgren wrote: > > > > > * Zwane Mwaikambo [050204 09:31]: > > > > On Fri, 4 Feb 2005, Tony Lindgren wrote: > > > > > > > > > Yes, it's safer to keep the timer periodic, although it's > > > > > used for oneshot purposes for the skips. If the timer interrupt > > > > > got missed for some reason, the system would be able to recover when > > > > > it's in periodic mode. > > > > > > > > > > And with some timers, we can do the reprogramming faster, as we just > > > > > need to load the new value. > > > > > > > > > > I could not figure out how to disable the interrupts for PIT > > > > > when local APIC is used and the ticks to skip is longer than PIT > > > > > would allow. So I just changed the mode temporarily to disable it. > > > > > > > > > > Does anybody know if there's a way to stop PIT interrupts while > > > > > keeping it in the periodic mode? > > > > > > > > disable_irq(0) ? > > > > > > Then the problem is that the CPU does not stay in sleep but wakes to > > > the first PIT interrupt AFAIK. > > > > I do not understand, do you want to disable the PIT from interrupting the > > processor and enable it interrupting at a later time? > > Yes, that right. PIT max skip ticks = 54 and local APIC timer > 1000. > PIT interrupt needs to be disabled to stay in sleep for over 54 ticks. > > But I think you're right, disable_irq(0) should do the trick :) > > Hmmm, we should be able to keep PIT irq disabled all the time when using > local APIC timer. I'll play with it a bit. Oops, no, PIT must be running at least when the system is busy. Otherwise time won't get updated during load, as we never get to the idle loop. Tony - 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/