Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754609Ab3HESXe (ORCPT ); Mon, 5 Aug 2013 14:23:34 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:5397 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754321Ab3HESXd (ORCPT ); Mon, 5 Aug 2013 14:23:33 -0400 X-Authority-Analysis: v=2.0 cv=P6i4d18u c=1 sm=0 a=Sro2XwOs0tJUSHxCKfOySw==:17 a=Drc5e87SC40A:10 a=pFOAptgLnqcA:10 a=5SG0PmZfjMsA:10 a=IkcTkHD0fZMA:10 a=meVymXHHAAAA:8 a=KGjhK52YXX0A:10 a=pvQ05lsfB1wA:10 a=2r-oGcCC-dEXE5J1Tj0A:9 a=QEXdDO2ut3YA:10 a=Sro2XwOs0tJUSHxCKfOySw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 67.255.60.225 Message-ID: <1375727010.22073.110.camel@gandalf.local.home> Subject: Re: [RFC] gcc feature request: Moving blocks into sections From: Steven Rostedt To: "H. Peter Anvin" Cc: Linus Torvalds , LKML , gcc , Ingo Molnar , Mathieu Desnoyers , Thomas Gleixner , David Daney , Behan Webster , Peter Zijlstra , Herbert Xu Date: Mon, 05 Aug 2013 14:23:30 -0400 In-Reply-To: <51FFEC56.6040206@linux.intel.com> References: <1375721715.22073.80.camel@gandalf.local.home> <1375725328.22073.101.camel@gandalf.local.home> <51FFEC56.6040206@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4-3 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1196 Lines: 28 On Mon, 2013-08-05 at 11:17 -0700, H. Peter Anvin wrote: > On 08/05/2013 10:55 AM, Steven Rostedt wrote: > > > > Well, as tracepoints are being added quite a bit in Linux, my concern is > > with the inlined functions that they bring. With jump labels they are > > disabled in a very unlikely way (the static_key_false() is a nop to skip > > the code, and is dynamically enabled to a jump). > > > > Have you considered using traps for tracepoints? A trapping instruction > can be as small as a single byte. The downside, of course, is that it > is extremely suppressed -- the trap is always expensive -- and you then > have to do a lookup to find the target based on the originating IP. No, never considered it, nor would I. Those that use tracepoints, do use them extensively, and adding traps like this would probably cause heissenbugs and make tracepoints useless. Not to mention, how would we add a tracepoint to a trap handler? -- Steve -- 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/