Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932279AbVIEIAi (ORCPT ); Mon, 5 Sep 2005 04:00:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932281AbVIEIAi (ORCPT ); Mon, 5 Sep 2005 04:00:38 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:56336 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S932279AbVIEIAi (ORCPT ); Mon, 5 Sep 2005 04:00:38 -0400 Date: Mon, 5 Sep 2005 09:00:28 +0100 From: Russell King To: Srivatsa Vaddagiri Cc: Nishanth Aravamudan , Con Kolivas , linux-kernel@vger.kernel.org, akpm@osdl.org, ck list Subject: Re: [PATCH 1/3] dynticks - implement no idle hz for x86 Message-ID: <20050905090028.D24051@flint.arm.linux.org.uk> Mail-Followup-To: Srivatsa Vaddagiri , Nishanth Aravamudan , Con Kolivas , linux-kernel@vger.kernel.org, akpm@osdl.org, ck list References: <20050831165843.GA4974@in.ibm.com> <200509031801.09069.kernel@kolivas.org> <20050903090650.B26998@flint.arm.linux.org.uk> <200509031814.49666.kernel@kolivas.org> <20050904201054.GA4495@us.ibm.com> <20050904212616.B11265@flint.arm.linux.org.uk> <20050905053225.GA4294@in.ibm.com> <20050905083728.A24051@flint.arm.linux.org.uk> <20050905074928.GA7924@in.ibm.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: <20050905074928.GA7924@in.ibm.com>; from vatsa@in.ibm.com on Mon, Sep 05, 2005 at 01:19:28PM +0530 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1412 Lines: 33 On Mon, Sep 05, 2005 at 01:19:28PM +0530, Srivatsa Vaddagiri wrote: > > Despite that, the timers as implemented on the hardware are not > > suitable for dyntick use - attempting to use them, you lose long > > term precision of the timer interrupts. > > Thats one of the problems I am seeing on x86 as well. Recovering > wall-time precisely after sleep is tough esepcially if the interrupt > source (PIT) and backing-time source (TSC/PM Timer/HPET) can > drift wrt each other. PPC64 should be much better I hope (which is what I > intend to take up next). This is why the config option to enable it on ARM has a warning in there about it. Some hardware timer implementations just aren't suitable for this, so users should be warned about it (and are on ARM.) > Tony was using it to signal that all CPUs are idle and timer are > being skipped. With the SMP changes I made, I felt it can be > substituted with the nohz_cpu_mask bitmap and hence I removed > it. Well, consider that definition removed from ARM. Forget it was even saw it in there. 8) -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - 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/