From owner-freebsd-current@FreeBSD.ORG Sun Oct 12 11:57:55 2003 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 95E5016A4B3 for ; Sun, 12 Oct 2003 11:57:55 -0700 (PDT) Received: from srv1.cosmo-project.de (srv1.cosmo-project.de [213.83.6.106]) by mx1.FreeBSD.org (Postfix) with ESMTP id D479F43FA3 for ; Sun, 12 Oct 2003 11:57:51 -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) h9CIvit2063286 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=OK); Sun, 12 Oct 2003 20:57:46 +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 h9CIvhS8094467 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 12 Oct 2003 20:57:43 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (localhost [127.0.0.1]) by cicely12.cicely.de (8.12.10/8.12.10) with ESMTP id h9CIvg2u058388; Sun, 12 Oct 2003 20:57:42 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: (from ticso@localhost) by cicely12.cicely.de (8.12.10/8.12.10/Submit) id h9CIvgWe058387; Sun, 12 Oct 2003 20:57:42 +0200 (CEST) (envelope-from ticso) Date: Sun, 12 Oct 2003 20:57:41 +0200 From: Bernd Walter To: "M. Warner Losh" Message-ID: <20031012185740.GS13791@cicely12.cicely.de> References: <20031011234314.P23991@root.org> <20031012.095503.129593225.imp@bsdimp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20031012.095503.129593225.imp@bsdimp.com> X-Operating-System: FreeBSD cicely12.cicely.de 5.1-CURRENT alpha User-Agent: Mutt/1.5.4i cc: current@freebsd.org cc: nate@root.org Subject: Re: Interrupt statistics? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: ticso@cicely.de List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 Oct 2003 18:57:55 -0000 On Sun, Oct 12, 2003 at 09:55:03AM -0600, M. Warner Losh wrote: > In message: <20031011234314.P23991@root.org> > Nate Lawson writes: > : Does anyone have recent statistics for interrupt latency and arrival > : timings? > > In -stable I know that we service fast interrupts in < 10us on a > 666MHz machine 99.2% of the time. I don't know about non-fast > interrupts, but other results suggest that we'd do 99+% in less than > 100us. This is to the first instruction of the ISR. The ISRs that > I've been running typically run for 2us (since they do 30 instructions > plus 2 ISA I/Os). >From the serial application I did recently I know that writing 8 bytes at 19200bps could pause the output for > 286us and < 429us after 5 bytes in about 50% tries with 16C552 ISA hardware. Given the fact we get the interrupt before the last stop bit goes out the real latency in handling is a multiple of this. However - this was with an old current and I can retry with a recent one once I get over the "no kernel output" problem. If things should be acurate I can modify ISA hardware with a micro- controller to do real measurements on a socket 7 HX board. -- B.Walter BWCT http://www.bwct.de ticso@bwct.de info@bwct.de