Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965219AbWIRO6v (ORCPT ); Mon, 18 Sep 2006 10:58:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965279AbWIRO6u (ORCPT ); Mon, 18 Sep 2006 10:58:50 -0400 Received: from tomts16-srv.bellnexxia.net ([209.226.175.4]:31425 "EHLO tomts16-srv.bellnexxia.net") by vger.kernel.org with ESMTP id S965219AbWIRO6t (ORCPT ); Mon, 18 Sep 2006 10:58:49 -0400 Date: Mon, 18 Sep 2006 10:53:35 -0400 From: Mathieu Desnoyers To: Jes Sorensen Cc: Ingo Molnar , Roman Zippel , Andrew Morton , tglx@linutronix.de, karim@opersys.com, Paul Mundt , linux-kernel@vger.kernel.org, Christoph Hellwig , Ingo Molnar , Greg Kroah-Hartman , Tom Zanussi , ltt-dev@shafik.org, Michel Dagenais Subject: Re: [PATCH 0/11] LTTng-core (basic tracing infrastructure) 0.5.108 Message-ID: <20060918145335.GD15605@Krystal> References: <450ABE08.2060107@opersys.com> <1158332447.5724.423.camel@localhost.localdomain> <20060915111644.c857b2cf.akpm@osdl.org> <20060915181907.GB17581@elte.hu> <20060915200559.GB30459@elte.hu> <20060915202233.GA23318@Krystal> <450BCAF1.2030205@sgi.com> <20060916173035.GA705@Krystal> <450E55BB.80208@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <450E55BB.80208@sgi.com> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.4.32-grsec (i686) X-Uptime: 10:47:22 up 26 days, 11:56, 4 users, load average: 2.42, 1.66, 1.48 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1575 Lines: 38 * Jes Sorensen (jes@sgi.com) wrote: > Mathieu Desnoyers wrote: > > And about those extra cycles.. according to : > > Documentation/kprobes.txt > > "6. Probe Overhead > > > > On a typical CPU in use in 2005, a kprobe hit takes 0.5 to 1.0 > > microseconds to process. Specifically, a benchmark that hits the same > > probepoint repeatedly, firing a simple handler each time, reports 1-2 > > million hits per second, depending on the architecture. A jprobe or > > return-probe hit typically takes 50-75% longer than a kprobe hit. > > When you have a return probe set on a function, adding a kprobe at > > the entry to that function adds essentially no overhead. > [snip] > > So, 1 microsecond seems more like 1500-2000 cycles to me, not 50. > > So call it 2000 cycles, now go measure it in *real* life benchmarks > and not some artificial I call this one syscall that hits the probe > every time in a tight loop, kinda thing. > > Show us some *real* numbers please. > You are late (I don't blame you about it, considering the size of this thread). It has been posted in the following email : http://linux.derkeiler.com/Mailing-Lists/Kernel/2006-09/msg04492.html Mathieu OpenPGP public key: http://krystal.dyndns.org:8080/key/compudj.gpg Key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - 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/