Date: Mon, 24 Dec 2001 08:51:16 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Peter Jeremy <peter.jeremy@alcatel.com.au> Cc: David Greenman <dg@root.com>, Bruce Evans <bde@zeta.org.au>, Matthew Dillon <dillon@apollo.backplane.com>, Mike Silbersack <silby@silby.com>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/dev/sio sio.c Message-ID: <83382.1009180276@critter.freebsd.dk> In-Reply-To: Your message of "Mon, 24 Dec 2001 16:22:47 %2B1100." <20011224162247.B85044@gsmx07.alcatel.com.au>
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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
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