From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758970AbZA2X7I (ORCPT ); Thu, 29 Jan 2009 18:59:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753279AbZA2X6z (ORCPT ); Thu, 29 Jan 2009 18:58:55 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:51360 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752905AbZA2X6y (ORCPT ); Thu, 29 Jan 2009 18:58:54 -0500 Date: Thu, 29 Jan 2009 15:58:52 -0800 (PST) Message-Id: <20090129.155852.161923905.davem@davemloft.net> To: tglx@linutronix.de, mingo@redhat.com CC: linux-kernel@vger.kernel.org Subject: x86's nmi_hz wrt. oprofile's nmi_timer_int.c From: David Miller X-Mailer: Mew version 6.1 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While working on an NMI watchdog implementation on sparc64 I noticed what seems to be a peculiar behavior of the NMI timer int oprofile support on x86. When the NMI watchdog tests itself at boot timer we start with nmi_hz equal to HZ. After the NMI watchdog self-test passes, nmi_hz is reduced down to '1'. The NMI timer int oprofile support simply uses DIE_NMI notifiers for it's implementation. But I don't see anything in the code of arch/x86/oprofile/nmi_timer_int.c nor the NMI watchdog infrastructure which will re-adjust nmi_hz back to HZ or something similar. Am I missing something?