Date: 26 Feb 2002 22:02:05 -0600 From: Bob Van Valzah <Bob@Talarian.Com> To: Robert Watson <rwatson@FreeBSD.ORG> Cc: Jorge Aldana <jorge@salk.edu>, Garance A Drosihn <drosih@rpi.edu>, smp@FreeBSD.ORG Subject: Re: Performance vs. Stable Message-ID: <1014782526.15635.22.camel@Relent.Bob.WhiteBarn.Com> In-Reply-To: <Pine.NEB.3.96L.1020226224905.38595O-100000@fledge.watson.org> References: <Pine.NEB.3.96L.1020226224905.38595O-100000@fledge.watson.org>
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On Tue, 2002-02-26 at 21:50, Robert Watson wrote: > > On 26 Feb 2002, Bob Van Valzah wrote: > > > I'm surprised by the results here. (Maybe I'm misinterpreting them?) It > > looks like -CURRENT is over 6x faster than -STABLE on null system calls. > > Forks and mmap seem about 2x faster but context switches are slower. > > > > It's interesting to note that WITNESS and friends slowed down null > > system calls by 11x and other kernel operations by about 3-5x. > > What is the 'null system call'? The cop-out answer: I don't write the benchmarks, I just run them :-) Seriously, I was wondering that myself, but I hadn't bothered to look it up till you asked. Consulting the manpage: http://www.bitmover.com/lmbench/lat_syscall.8.html It looks like Larry was a bit fast and loose with language in writing the summary report (maybe to make it fit in the header). It appears to be the time needed to write one byte to /dev/null. I don't see why that's any more "null" than say, getpid(). Bob To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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