From owner-freebsd-hackers@FreeBSD.ORG Fri Jul 24 14:51:56 2009 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 23A5E1065672 for ; Fri, 24 Jul 2009 14:51:56 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id E775C8FC1D for ; Fri, 24 Jul 2009 14:51:55 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id 89FDA46B85; Fri, 24 Jul 2009 10:51:55 -0400 (EDT) Received: from jhbbsd.hudson-trading.com (unknown [209.249.190.8]) by bigwig.baldwin.cx (Postfix) with ESMTPA id 9B68E8A0A1; Fri, 24 Jul 2009 10:51:54 -0400 (EDT) From: John Baldwin To: Alexander Best Date: Fri, 24 Jul 2009 07:47:45 -0400 User-Agent: KMail/1.9.7 References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200907240747.45738.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0.1 (bigwig.baldwin.cx); Fri, 24 Jul 2009 10:51:54 -0400 (EDT) X-Virus-Scanned: clamav-milter 0.95.1 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-2.5 required=4.2 tests=AWL,BAYES_00, DATE_IN_PAST_03_06,RDNS_NONE autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on bigwig.baldwin.cx Cc: Alexey Shuvaev , freebsd-hackers@freebsd.org Subject: Re: checking number of parallel ports installed and their port adresses X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 24 Jul 2009 14:51:56 -0000 On Friday 24 July 2009 6:42:34 am Alexander Best wrote: > thanks for the hint. > > if spent a bit of time and turned the in/out opcodes to ppi ioctls. actually i > was very surprised about the results since you said the overhead wouldn't be > that big. > > uploading a 256 kbyte file i got the following results: > > using ppi: 17.120 seconds > using in/out opcodes: 8.001 seconds > > so i think i'll rather stick to my old inline assembly code even if it can't > be considered nice programming style, but the ppi overhead isn't something i > can cope with in my app. Hmmm, that is a bit much. Though I do suppose you are incurring a user -> kernel -> user transition for each I/O access. -- John Baldwin