From owner-freebsd-questions Sun Sep 30 14: 6:38 2001 Delivered-To: freebsd-questions@freebsd.org Received: from hotmail.com (f103.law11.hotmail.com [64.4.17.103]) by hub.freebsd.org (Postfix) with ESMTP id EF50437B406 for ; Sun, 30 Sep 2001 14:06:32 -0700 (PDT) Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Sun, 30 Sep 2001 14:06:32 -0700 Received: from 24.116.152.150 by lw11fd.law11.hotmail.msn.com with HTTP; Sun, 30 Sep 2001 21:06:32 GMT X-Originating-IP: [24.116.152.150] From: "Charles Burns" To: questions@freebsd.org Subject: GCC 3.0 terrible for Athlon Date: Sun, 30 Sep 2001 14:06:32 -0700 Mime-Version: 1.0 Content-Type: text/plain; format=flowed Message-ID: X-OriginalArrivalTime: 30 Sep 2001 21:06:32.0882 (UTC) FILETIME=[C8435120:01C149F3] Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG This may be old news, but http://www.cs.utk.edu/~rwhaley/ATLAS/gcc30.html describes some serious problems that GCC 3.0 has when using Athlon processors. Here's a clip: --------------- From the experiments described below, I think it is highly probable that there are two significant problems with gcc 3.0 on x86: The 3.0 fetch scheduler is optimized for Pentiums, to the very great detriment of Athlons. The scheduling algorithm used in the 2.9x series is much better for Athlons (2.96-80 has this problem as well). For ATLAS's kernel on Athlons, this problem causes an almost 50% drop in performance. 3.0's fpu stack handling is inferior to 2.9x's on all x86 platforms (2.96-80 does not have this problem, if you turn up optimization over that required in earlier releases). For ATLAS's kernel on any x86 (actually, confirmed for PIII & Athlon only), this problem causes a roughly 10% drop in performance. ---------------- Ouch! The performace figures shouldn't bee too different for BSD. Charles Burns _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message