From owner-freebsd-hackers@FreeBSD.ORG Fri Apr 9 04:33:01 2004 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7411116A4CE for ; Fri, 9 Apr 2004 04:33:01 -0700 (PDT) Received: from srv1.cosmo-project.de (srv1.cosmo-project.de [213.83.6.106]) by mx1.FreeBSD.org (Postfix) with ESMTP id 00C0F43D31 for ; Fri, 9 Apr 2004 04:33:00 -0700 (PDT) (envelope-from ticso@cicely12.cicely.de) Received: from cicely5.cicely.de (cicely5.cicely.de [IPv6:3ffe:400:8d0:301:200:92ff:fe9b:20e7]) (authenticated bits=0) i39BUxUS016234 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=OK); Fri, 9 Apr 2004 13:31:04 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (cicely12.cicely.de [IPv6:3ffe:400:8d0:301::12]) by cicely5.cicely.de (8.12.10/8.12.10) with ESMTP id i39BUPhn085262 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 9 Apr 2004 13:30:26 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (localhost [127.0.0.1]) by cicely12.cicely.de (8.12.11/8.12.11) with ESMTP id i39BUPhD012764; Fri, 9 Apr 2004 13:30:25 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: (from ticso@localhost) by cicely12.cicely.de (8.12.11/8.12.11/Submit) id i39BUMNO012763; Fri, 9 Apr 2004 13:30:22 +0200 (CEST) (envelope-from ticso) Date: Fri, 9 Apr 2004 13:30:22 +0200 From: Bernd Walter To: "M. Warner Losh" Message-ID: <20040409113021.GK5279@cicely12.cicely.de> References: <20040407170422.GF567@funkthat.com> <20040408024455.GC20138@dhcp01.pn.xcllnt.net> <20040408.123443.101835222.imp@bsdimp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040408.123443.101835222.imp@bsdimp.com> X-Operating-System: FreeBSD cicely12.cicely.de 5.2-CURRENT alpha User-Agent: Mutt/1.5.6i X-Spam-Status: No, hits=-4.9 required=3.0 tests=BAYES_00 autolearn=ham version=2.63 X-Spam-Report: * -4.9 BAYES_00 BODY: Bayesian spam probability is 0 to 1% * [score: 0.0000] X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on cicely12.cicely.de cc: freebsd-hackers@freebsd.org cc: atkin901@yahoo.com cc: marcel@xcllnt.net Subject: Re: polling for sio? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: ticso@cicely.de List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Apr 2004 11:33:01 -0000 On Thu, Apr 08, 2004 at 12:34:43PM -0600, M. Warner Losh wrote: > In message: <20040408024455.GC20138@dhcp01.pn.xcllnt.net> > Marcel Moolenaar writes: > : On Wed, Apr 07, 2004 at 03:36:02PM -0700, othermark wrote: > : > I have a multi-port PCI card under puc and sio that has 4 19200 > : > connections to it now, and when data is streaming across all of > : > them at once, I get several silo overflows. Would it be better > : > to run this under puc + uart? > : > : Not really. The problem is that puc(4) iterates over all ports in > : the same way whether you use uart(4) or sio(4). So, puc(4) is > : the problem more that sio(4) or uart(4). However, uart(4) has the > : beginnings of an interface that puc(4) could use to figure out > : which UART needs attention without actually calling the interrupt > : routine for each of them. > > Yes, but at 19200 baud, his problems likely aren't related to the > iteration. They are likely related to the fact that he said his > interrupt is shared and therefore not fast. We have horrible > interrupt latency in current when you want to get to the FIFOs of > UARTs quickly :-(. Those cards are just what they are - cheap. They have very small FIFOs and they don't use DMA. IRQ sharing makes them even worse than traditional ISA stuff. My advise for cost efficient and fast serials is getting USB ones. Even noname USB serials do much better then puc(4) based. E.g. the FT232BM (uftdi(4)) has 128 bytes send and 384 bytes receive buffer plus your USB controller does DMA. At best you would add a cheap OHCI card if your onboard USB is UHCI based as OHCI is less CPU intensive. -- B.Walter BWCT http://www.bwct.de ticso@bwct.de info@bwct.de