From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756683AbZBWEeS (ORCPT ); Sun, 22 Feb 2009 23:34:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752666AbZBWEeG (ORCPT ); Sun, 22 Feb 2009 23:34:06 -0500 Received: from one.firstfloor.org ([213.235.205.2]:39523 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752523AbZBWEeG (ORCPT ); Sun, 22 Feb 2009 23:34:06 -0500 Date: Mon, 23 Feb 2009 05:52:00 +0100 From: Andi Kleen To: David Miller Cc: andi@firstfloor.org, linux-kernel@vger.kernel.org Subject: Re: x86's nmi_hz wrt. oprofile's nmi_timer_int.c Message-ID: <20090223045159.GR26292@one.firstfloor.org> References: <20090129.155852.161923905.davem@davemloft.net> <873ae6wgd6.fsf@basil.nowhere.org> <20090222.201152.169082487.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090222.201152.169082487.davem@davemloft.net> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Again, the code in nmi_timer_int.c doesn't. > > It uses the NMI watchdog timer interrupts, it catches DIE_NMI > events. > > > Does that answer your question? > > Not really. Ah see what you mean now. The nmi_timer_int code can only be active ever when the cpu is not known to nmi_int.c and when the nmi watchdog is in io apic mode. But IO apic mode doesn't use the fast check/slowdown because it always runs at HZ frequency. That only happens in LAPIC mode. The standard fallback mode for unknown CPU is the non NMI timer fallback in oprofile_init, the IO APIC mode happens near never in practice. -Andi -- ak@linux.intel.com -- Speaking for myself only.