From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15141 invoked by alias); 1 Oct 2006 03:47:36 -0000 Received: (qmail 15132 invoked by uid 22791); 1 Oct 2006 03:47:35 -0000 X-Spam-Status: No, hits=-2.3 required=5.0 tests=AWL,BAYES_00,FORGED_RCVD_HELO,TW_CP X-Spam-Check-By: sourceware.org Received: from tomts22.bellnexxia.net (HELO tomts22-srv.bellnexxia.net) (209.226.175.184) by sourceware.org (qpsmtpd/0.31) with ESMTP; Sun, 01 Oct 2006 03:47:33 +0000 Received: from krystal.dyndns.org ([65.95.39.115]) by tomts22-srv.bellnexxia.net (InterMail vM.5.01.06.13 201-253-122-130-113-20050324) with ESMTP id <20061001034729.QCJB10262.tomts22-srv.bellnexxia.net@krystal.dyndns.org> for ; Sat, 30 Sep 2006 23:47:29 -0400 Received: from localhost (localhost [127.0.0.1]) (uid 1000) by krystal.dyndns.org with local; Sat, 30 Sep 2006 23:42:12 -0400 id 001C2491.451F3914.00000920 Date: Sun, 01 Oct 2006 03:47:00 -0000 From: Mathieu Desnoyers To: Nicholas Miell Cc: Martin Bligh , "Frank Ch. Eigler" , Masami Hiramatsu , prasanna@in.ibm.com, Andrew Morton , Ingo Molnar , Paul Mundt , linux-kernel , Jes Sorensen , Tom Zanussi , Richard J Moore , Michel Dagenais , Christoph Hellwig , Greg Kroah-Hartman , Thomas Gleixner , William Cohen , ltt-dev@shafik.org, systemtap@sources.redhat.com, Alan Cox , Jeremy Fitzhardinge , Karim Yaghmour , Pavel Machek , Joe Perches , "Randy.Dunlap" , "Jose R. Santos" Subject: Re: Performance analysis of Linux Kernel Markers 0.20 for 2.6.17 Message-ID: <20061001034212.GB13527@Krystal> References: <20060930180157.GA25761@Krystal> <1159642933.2355.1.camel@entropy> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <1159642933.2355.1.camel@entropy> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.4.32-grsec (i686) X-Uptime: 23:31:55 up 39 days, 40 min, 1 user, load average: 0.24, 0.21, 0.20 User-Agent: Mutt/1.5.13 (2006-08-11) X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2006-q4/txt/msg00000.txt.bz2 * Nicholas Miell (nmiell@comcast.net) wrote: > On Sat, 2006-09-30 at 14:01 -0400, Mathieu Desnoyers wrote: > > Hi, > > > > Following the huge discussion thread about tracing/static vs dynamic > > instrumentation/markers, a consensus seems to emerge about the need for a > > marker system in the Linux kernel. The main issues this mechanism addresses are: > > > > - Identify code important to runtime data collection/analysis tools in tree so > > that it follows the code changes naturally. > > - Be visually appealing to kernel developers. > > - Have a very low impact on the system performance. > > - Integrate in the standard kernel infrastructure : use C and loadable modules. > > > > The time has come for some performance measurements of the Linux Kernel Markers, > > which follows. I attach a PDF with tables and charts which condense these > > results. > > Has anyone done any performance measurements with the "regular function > call replaced by a NOP" type of marker? > Here it is (on the same setup as the other tests : Pentium 4, 3 GHz) : * Execute an empty loop - Without marker NR_LOOPS : 10000000 time delta (cycles): 15026497 cycles per loop : 1.50 - With 5 NOPs NR_LOOPS : 100000 time delta (cycles): 300157 cycles per loop : 3.00 added cycles per loop for nops : 3.00-1.50 = 1.50 * Execute a loop of memcpy 4096 bytes - Without marker NR_LOOPS : 10000 time delta (cycles): 12981555 cycles per loop : 1298.16 - With 5 NOPs NR_LOOPS : 10000 time delta (cycles): 12983925 cycles per loop : 1298.39 added cycles per loop for nops : 0.23 If we compare this approach to the jump-over-call markers (in cycles per loop) : NOPs Jump over call generic Jump over call optimized empty loop 1.50 1.17 2.50 memcpy 0.23 2.12 0.07 Mathieu OpenPGP public key: http://krystal.dyndns.org:8080/key/compudj.gpg Key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68