Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756716AbYAIWjh (ORCPT ); Wed, 9 Jan 2008 17:39:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753474AbYAIWjL (ORCPT ); Wed, 9 Jan 2008 17:39:11 -0500 Received: from e2.ny.us.ibm.com ([32.97.182.142]:48515 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752270AbYAIWjJ (ORCPT ); Wed, 9 Jan 2008 17:39:09 -0500 Subject: Re: [PATCH] Kprobes: Add kprobes smoke tests that run on boot From: Jim Keniston To: Andi Kleen Cc: ananth@in.ibm.com, akpm@linux-foundation.org, lkml , mingo@elte.hu, mhiramat@redhat.com, davem@davemloft.net, hskinnemoen@atmel.com In-Reply-To: <20080109212103.GB15612@one.firstfloor.org> References: <20080108063334.GA29385@in.ibm.com> <1199833842.3914.33.camel@dyn9047018096.beaverton.ibm.com> <20080108232841.GD2117@one.firstfloor.org> <1199910240.4162.31.camel@dyn9047018096.beaverton.ibm.com> <20080109212103.GB15612@one.firstfloor.org> Content-Type: text/plain Date: Wed, 09 Jan 2008 14:33:58 -0800 Message-Id: <1199918039.4162.40.camel@dyn9047018096.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.8.3 (2.8.3-2.fc6) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1449 Lines: 33 On Wed, 2008-01-09 at 22:21 +0100, Andi Kleen wrote: > On Wed, Jan 09, 2008 at 12:24:00PM -0800, Jim Keniston wrote: > > On Wed, 2008-01-09 at 00:28 +0100, Andi Kleen wrote: > > > > I have no problem with that, but if we want to make it buildable as a > > > > module, the call to get_kprobe() needs to be replaced with some other > > > > gcc-inline-defeating mechanism, or we need to export get_probe(). I > > > > > > It's still unclear where noinline does not work (do you have details on that? > > > It sounds a little dubious) ... > > > > Here's a simplified version of a module we've used to gauge kprobes > > performance. On my system (i386, 2.6.23-rc8 at the moment, gcc version > > 4.1.2), the module calls the (empty) probed function (probeme) niter > > times, but reports zero probe hits -- indicating probeme was inlined > > even though it was declared noinline. > > Yes indeed looks like a gcc bug. Have you reported it? > > -Andi There's already a gcc bug report that appears to describe the same problem: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34563 There seems to be some doubt as to whether it's really a bug, so I added my 2 cents, including a pointer to this thread. Jim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/