From owner-freebsd-hackers Tue Aug 7 11:37:26 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from albatross.prod.itd.earthlink.net (albatross.mail.pas.earthlink.net [207.217.120.120]) by hub.freebsd.org (Postfix) with ESMTP id 3749737B410; Tue, 7 Aug 2001 11:37:21 -0700 (PDT) (envelope-from tlambert2@mindspring.com) Received: from mindspring.com (dialup-209.244.105.118.Dial1.SanJose1.Level3.net [209.244.105.118]) by albatross.prod.itd.earthlink.net (EL-8_9_3_3/8.9.3) with ESMTP id LAA09771; Tue, 7 Aug 2001 11:37:17 -0700 (PDT) Message-ID: <3B703585.CE87BBD3@mindspring.com> Date: Tue, 07 Aug 2001 11:37:57 -0700 From: Terry Lambert Reply-To: tlambert2@mindspring.com X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony} (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Zach Brown Cc: Mike Smith , Matt Dillon , freebsd-hackers@freebsd.org Subject: Re: Allocate a page at interrupt time References: <200108070739.f777dmi08218@mass.dis.org> <3B6FB0AE.8D40EF5D@mindspring.com> <20010807134436.B20259@erasmus.off.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Zach Brown wrote: > > That Microsoft demonstrated that wiring down interrupts > > to a particular CPU was a good idea, and kicked both Linux' > > and FreeBSD's butt in the test at ZD Labs? > > No, Terry, this is not what was demonstrated by those tests. Will this > myth never die? Do Mike and I have to write up a nice white paper? :) That would be nice, actually. > > The environment was ridigly specified: quad cpu box, four eepro 100mb > interfaces, and a _heavy_ load of short lived connections fetching static > cached content. The test was clearly designed to stress concurrency in > the network stack, with heavy low latency interrupt load. Neither Linux > nor FreeBSD could do this well at the time. There was a service pack > issed a few months before the test that 'threaded' NT's stack.. > > It was not a mistake that the rules of the tests forbid doing the sane > thing and running on a system with a single very fast cpu, lots of mem, > and gigabit interface with an actual published interface for coalescing > interrupts. That would have performed better and been cheaper. I have soft interrupt coelescing changes for most FreeBSD drivers written by Bill Paul; the operation is trivial, and Bill has structured his drivers well for doing that sort of thing. I personally don't think the test was unfair; it seems to me to be representative of most web traffic, which averages 8k a page for most static content, according to published studies. > Thats what pisses me off about the tests to this day. The problem > people are faced with is is "how do I serve this static content > reliably and cheaply", not, "what OS should I serve my content > with, now that I've bought this ridiculous machine?". 8-) 8-). > Its sad that people consistently insist on drawing insane > conclusions from these benchmark events. I think that concurrency in the TCP stack is something that needs to be addressed; I'm glad they ran the benchmark, if only for that. Even if we both agree on the conclusions, agreeing isn't going to change people's perceptions, but beating them on their terms _will_, so it's a worthwhile pursuit. I happen to agree that their test indicated some shortcomings in the OS designs; regardless of whether we think they were carefully chosen to specifically emphasize those shortcomings, it doesn't change the fact that they are shortcomings. There's no use crying over spilt milk: the question is what can be done about it, besides trying to deny the validity of the tests. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message