From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752656Ab1HKSs2 (ORCPT ); Thu, 11 Aug 2011 14:48:28 -0400 Received: from mga09.intel.com ([134.134.136.24]:65431 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751440Ab1HKSs1 (ORCPT ); Thu, 11 Aug 2011 14:48:27 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,352,1309762800"; d="scan'208";a="37616903" From: Andi Kleen To: Alex Neronskiy Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, Ingo Molnar , Don Zickus , Mandeep Singh Baines , Alex Neronskiy Subject: Re: [PATCH v6 2/2] Output stall data in debugfs References: <1312999364-21104-1-git-send-email-zakmagnus@chromium.org> <1312999364-21104-2-git-send-email-zakmagnus@chromium.org> Date: Thu, 11 Aug 2011 11:48:26 -0700 In-Reply-To: <1312999364-21104-2-git-send-email-zakmagnus@chromium.org> (Alex Neronskiy's message of "Wed, 10 Aug 2011 11:02:44 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Alex Neronskiy writes: > From: Alex Neronskiy > > Instead of using the log, use debugfs for output of both stall > lengths and stack traces. Printing to the log can result in > watchdog touches, Why? Because of printk being slow or something else? The first could be probably workarounded, especially if you already have "two buffers" > distorting the very events being measured. > Additionally, the information will not distract from lockups > when users view the log. > > A two-buffer system is used to ensure that the trace information > can always be recorded without contention. This implies that kernel bug reports will often not contain the back trace, right? Seems like a bad thing to me because it will make bug reports worse. -Andi -- ak@linux.intel.com -- Speaking for myself only