From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932897AbXGTVGq (ORCPT ); Fri, 20 Jul 2007 17:06:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758944AbXGTVGh (ORCPT ); Fri, 20 Jul 2007 17:06:37 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:46214 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759317AbXGTVGh (ORCPT ); Fri, 20 Jul 2007 17:06:37 -0400 Date: Fri, 20 Jul 2007 14:06:20 -0700 From: Andrew Morton To: Konrad Rzeszutek Cc: darnok@68k.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Inhibit NMI watchdog when Alt-SysRq-T operation is underway. Message-Id: <20070720140620.e742a2b9.akpm@linux-foundation.org> In-Reply-To: <20070720111823.GA2334@andromeda.dapyr.net> References: <20070709140242.GA18098@andromeda.dapyr.net> <20070709155302.GB26570@andromeda.dapyr.net> <20070713164504.66b72e74.akpm@linux-foundation.org> <20070720111823.GA2334@andromeda.dapyr.net> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 Jul 2007 07:18:23 -0400 Konrad Rzeszutek wrote: > I tested your patch along with mine and found two things out: > > 1). Missing this patch (for i386 platform) > > diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c > index 90da057..9f3a7ff 100644 > --- a/arch/i386/kernel/traps.c > +++ b/arch/i386/kernel/traps.c > @@ -207,6 +207,7 @@ static void print_trace_address(void *da > { > printk("%s [<%08lx>] ", (char *)data, addr); > print_symbol("%s\n", addr); > + touch_nmi_watchdog(); > } ok... > static struct stacktrace_ops print_trace_ops = { > > > 2). If I run Alt-SysRq-t about 5000 times in a loop, the slow down > with this change is about 5%. Is this a big issue? (This was > testing both i686 and x86_64). > I'm surprised. I assume this was when it was printing to a high-speed device? console or netconsole? I don't think we need to spend too much time optimising sysrq-T performance ;)