From owner-cvs-all Sun Dec 23 23:53:43 2001 Delivered-To: cvs-all@freebsd.org Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.86.163]) by hub.freebsd.org (Postfix) with ESMTP id 8251C37B41C; Sun, 23 Dec 2001 23:53:35 -0800 (PST) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.11.6/8.11.6) with ESMTP id fBO7pGl83384; Mon, 24 Dec 2001 08:51:17 +0100 (CET) (envelope-from phk@critter.freebsd.dk) To: Peter Jeremy Cc: David Greenman , Bruce Evans , Matthew Dillon , Mike Silbersack , cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/dev/sio sio.c In-Reply-To: Your message of "Mon, 24 Dec 2001 16:22:47 +1100." <20011224162247.B85044@gsmx07.alcatel.com.au> Date: Mon, 24 Dec 2001 08:51:16 +0100 Message-ID: <83382.1009180276@critter.freebsd.dk> From: Poul-Henning Kamp Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In message <20011224162247.B85044@gsmx07.alcatel.com.au>, Peter Jeremy writes: >>My guess would be that only four people in the project who have >>ever measured our interrupt latency: Bruce, Louie, Warner and me. > >That's definitely an under-estimate. Andrew Gallatin posted his >latency measurements on a Alpha h/w. I think I've seen one or two >other people indicate that they'd made measurements on -hackers. I've >also done some limited latency testing on both i386 and Alpha's. Sorry, but I don't think so. The only measurements I have seen which document the _actual_ interrupt latency are from the above people. I have seen people measuring the spread of interrupt latency, but that is not the same as the interrupt latency. To explain the difference more graphically: Measuring the interrupt latency means measuring the distance from bulls-eye to the hole in a target, measuring the spread means looking at how close the holes are on a blank sheet target. Very few people have hardware that allows them to see where the bulls-eye actually is. (Cost ~= USD1000). -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message