From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Thu, 26 Feb 2009 16:58:12 +0000 (GMT) Received: from h5.dl5rb.org.uk ([81.2.74.5]:55227 "EHLO h5.dl5rb.org.uk") by ftp.linux-mips.org with ESMTP id S20808686AbZBZQ6I (ORCPT ); Thu, 26 Feb 2009 16:58:08 +0000 Received: from h5.dl5rb.org.uk (localhost.localdomain [127.0.0.1]) by h5.dl5rb.org.uk (8.14.3/8.14.3) with ESMTP id n1QGw2mL000352; Thu, 26 Feb 2009 16:58:03 GMT Received: (from ralf@localhost) by h5.dl5rb.org.uk (8.14.3/8.14.3/Submit) id n1QGw0Fx000350; Thu, 26 Feb 2009 16:58:00 GMT Date: Thu, 26 Feb 2009 16:58:00 +0000 From: Ralf Baechle To: David Daney Cc: linux-mips@linux-mips.org Subject: Re: [PATCH] MIPS: Handle removal of 'h' constraint in GCC 4.4 Message-ID: <20090226165800.GA31972@linux-mips.org> References: <1235516662-24919-1-git-send-email-ddaney@caviumnetworks.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1235516662-24919-1-git-send-email-ddaney@caviumnetworks.com> User-Agent: Mutt/1.5.18 (2008-05-17) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 21974 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Tue, Feb 24, 2009 at 03:04:22PM -0800, David Daney wrote: > Due to the removal of the 'h' asm constraint in GCC-4.4, we need to > adjust the computation in delay.h It's time to take a step back and think over the whole thing once more. Inlining __udelay can be problematic on some processors where the execution performance of the delay loop will be different if the loop is crossing a cacheline or not. That seems to particularly hit R10000 systems often. The number of the loop interations does the wrong tradeoff between accuracy and the value range needed. The resulting overflows on a HZ=128 4000 BogoMIPS machine are fantastic :-) Time to reimplement udelay I'd say. Ralf