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From: libes@cme.nist.gov (Don Libes)
Newsgroups: comp.unix.wizards
Subject: Re: usleep by poll()
Message-ID: <1011@muffin.cme.nist.gov>
Date: 2 Apr 91 01:08:04 GMT
References: <6925@auspex.auspex.com> <999@muffin.cme.nist.gov> <127226@uunet.UU.NET>
Organization: National Institute of Standards and Technology
Lines: 21

In article <127226@uunet.UU.NET> rbj@uunet.UU.NET (Root Boy Jim) writes:
}In article <999@muffin.cme.nist.gov> libes@cme.nist.gov (Don Libes) writes:
}The BSD analog to this function is defined in terms of microseconds
}>while poll() is defined in terms of milliseconds.  For compatibility,
}>this function provides accuracy "over the long run" by truncating
}>actual requests to milliseconds and accumulating microseconds across
}>calls with the idea that you are probably calling it in a tight loop,
}>and that over the long run, the error will even out.

}Yeah, but what's the best resolution you've ever seen?
}Ten milliseconds seems to be the lowest. Since the average
}error is have the smallest scheduling interval, why bother?

Room for improvement in the future, and compatibility with such.
Why did BSD provide usleep in the first place?

}Perhaps they replaced the monster in 225's basement with a Cray?

In fact, they did.  NIST just received a Cray YMP.  

Don Libes          libes@cme.nist.gov      ...!uunet!cme-durer!libes