Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751736AbZJWKTA (ORCPT ); Fri, 23 Oct 2009 06:19:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751625AbZJWKTA (ORCPT ); Fri, 23 Oct 2009 06:19:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10702 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751616AbZJWKS7 (ORCPT ); Fri, 23 Oct 2009 06:18:59 -0400 Date: Fri, 23 Oct 2009 12:18:41 +0200 (CEST) From: John Kacur X-X-Sender: jkacur@localhost.localdomain To: Ingo Molnar cc: Frederic Weisbecker , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [performance problem] CONFIG_DYNAMIC_FTRACE: Increased kernel build times In-Reply-To: <520f0cf10910230307k91d0c80sa3d69bcd74d6e1f1@mail.gmail.com> Message-ID: References: <20091023074533.GA10067@elte.hu> <520f0cf10910230307k91d0c80sa3d69bcd74d6e1f1@mail.gmail.com> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-615147209-1256293126=:3549" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1431 Lines: 42 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-615147209-1256293126=:3549 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT 2009/10/23 Ingo Molnar wrote: > > Steve, > > i did an 64-bit allyesconfig build test (with debug_info disabled), with > and without CONFIG_DYNAMIC_FTRACE set. > > The build time results are: > > ?-CONFIG_DYNAMIC_FTRACE: ? 266.30 > ?+CONFIG_DYNAMIC_FTRACE: ? 296.07 (+11.2%) > > So we get more than 10% build time overhead. > > That's quite high - higher than what i remember having measured > originally when the first iteration of the mcount code went in. > > This extra overhead comes from the mcount post-processing script > (scripts/recordmcount.pl) that runs objcopy as well and is written in > Perl. I think this whole angle needs to be improved - 10% is way too > high of a price to pay. Hi Ingo, do you still have the profiling data to share with us? Was the problem more in objcopy / objdump, rather than in the perl script itself? Thanks John --8323328-615147209-1256293126=:3549-- -- 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/