From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758677AbYDKVoG (ORCPT ); Fri, 11 Apr 2008 17:44:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755336AbYDKVn4 (ORCPT ); Fri, 11 Apr 2008 17:43:56 -0400 Received: from wx-out-0506.google.com ([66.249.82.231]:24779 "EHLO wx-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752616AbYDKVnz (ORCPT ); Fri, 11 Apr 2008 17:43:55 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=rMphKxUv+2N8bQbVT77Qr2k+njI4qKXtrwJgie4pdIkSBcrcW7tPHc4WMcy8PeJvuokWvlLVMkrlHmSCtGNHrnEc/4Prim4hXaBawGScLQubPasKfgPmLnThgdrFfkaB86xoOw2JC6q29Dcav1SloIBEa3W8CyuW7dxBsPdG08g= Message-ID: <7b97a12b0804111443j5ecacfe8i753f54a39093a1ed@mail.gmail.com> Date: Fri, 11 Apr 2008 18:43:52 -0300 From: "Gary Shi" To: linux-kernel@vger.kernel.org Subject: get a still sysrq-t call trace, not a moving one MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi friends, when I read sysrq-t call trace, I find the collected call trace for some cases is not a still snapshot, but a moving one. After checking show_state src, I realize other cpus are not frozen when one cpu is doing show_state; thus some task switching can occur among those cpus, even the cpu doing sysrq for some kind of kernels. This moving call traces make debugging much more difficult, or even impossible for some cases, since some tasks have been switched in/out which make us lose the trace of some important data, like who is holding a lock when lots of threads are blocked on the lock. In order to get a still image of sysrq-t call trace, I'd like to suggest freezing all other cpus and disabling irq of local cpu. Any ideas about this? Thanx -gys pls cc me when you reply since I haven't subscribed to the mailing list.