From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751454AbVH3XiT (ORCPT ); Tue, 30 Aug 2005 19:38:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751453AbVH3XiT (ORCPT ); Tue, 30 Aug 2005 19:38:19 -0400 Received: from cantor.suse.de ([195.135.220.2]:21471 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S1751451AbVH3XiS (ORCPT ); Tue, 30 Aug 2005 19:38:18 -0400 From: Andi Kleen To: "Luck, Tony" Subject: Re: [PATCH] Only process_die notifier in ia64_do_page_fault if KPROBES is configured. Date: Wed, 31 Aug 2005 01:38:08 +0200 User-Agent: KMail/1.8 Cc: "Christoph Lameter" , "Rusty Lynch" , "Lynch, Rusty" , linux-mm@kvack.org, prasanna@in.ibm.com, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, "Keshavamurthy, Anil S" References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200508310138.09841.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 31 August 2005 01:05, Luck, Tony wrote: > >Please do not generate any code if the feature cannot ever be > >used (CONFIG_KPROBES off). With this patch we still have lots of > >unnecessary code being executed on each page fault. > > I can (eventually) wrap this call inside the #ifdef CONFIG_KPROBES. At least the original die notifiers were designed as a generic debugger interface, not a kprobes specific thing. So I don't think it's a good idea. Given most debuggers don't need the early page fault hook and it's mostly needed for a special case in kprobes, but it doesn't seem nice to only offer a subset of the hooks with specific config options. Also with the inline the test should be essentially a single test of a global variable and jump. Hardly a big performance issue, no? -Andi