From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1645 invoked by alias); 12 Jul 2005 20:29:27 -0000 Mailing-List: contact gcc-help-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-help-owner@gcc.gnu.org Received: (qmail 1631 invoked by uid 22791); 12 Jul 2005 20:29:24 -0000 Received: from web80010.mail.yahoo.com (HELO web80010.mail.yahoo.com) (66.163.168.140) by sourceware.org (qpsmtpd/0.30-dev) with SMTP; Tue, 12 Jul 2005 20:29:24 +0000 Received: (qmail 21661 invoked by uid 60001); 12 Jul 2005 20:29:21 -0000 Message-ID: <20050712202921.21659.qmail@web80010.mail.yahoo.com> Received: from [66.228.171.14] by web80010.mail.yahoo.com via HTTP; Tue, 12 Jul 2005 13:29:21 PDT Date: Tue, 12 Jul 2005 20:29:00 -0000 From: girish vaitheeswaran Subject: profile directed feedback. To: gcc-help@gcc.gnu.org MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-SW-Source: 2005-07/txt/msg00121.txt.bz2 Has anyone gotten performance gains on account of profile directed feedback optimization. I used gcc-3.4.3 and tried using profile directed feedback. This is what I did 1. Compiled the program using -fprofile-generate. I used this flag both in the compile flags and as part of the link flags. I also had to use libgcov.a during the link phase otherwise it would die looking for gcov functions. 2. Ran a representative work-load 3. Followed (1) except that instead of -fprofile-generate used -fprofile-use I had to drop the "-fprofile-use" on 2 files as they had corrupted profile data. So far so good. When I ran the profile directed feedback optimized executable, the performance was 20% slower. Anyone has experience with PDF they can share and point out what I am doing wrong? Thanks -girish