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From: wls@astrovax.UUCP (William L. Sebok)
Newsgroups: net.bugs.uucp
Subject: Re: 4.2 uucp performance problems?
Message-ID: <547@astrovax.UUCP>
Date: Fri, 15-Feb-85 19:53:57 EST
Article-I.D.: astrovax.547
Posted: Fri Feb 15 19:53:57 1985
Date-Received: Sun, 17-Feb-85 05:55:11 EST
References: <1363@hao.UUCP> <13500001@uicsl.UUCP> <442@down.FUN> <288@petrus.UUCP>
Organization: Princeton Univ. Astrophysics
Lines: 26

>> /* "sleep" for n clock ticks */
>> #include <sys/time.h>
>> nap(n)
>> {
>> ...
>> }
>> 
>> this assumes a 60 hz clock.  your mileage may vary.
>> 
>> 	peter
> 
> Beware, although some 4.2 code, such as accounting stuff, still assumes
> the clock rate is 60 ticks per sec, I believe a vanilla 4.2 on a vaxen
> actually runs at 100 ticks per sec.

This is really irrelevent, since the above code DEFINES a 60 HZ clock, or at
least defines the units for this nap() to be in 60ths of a second. The 4.2 BSD
select() call used in this code allows time to be specified to the microsecond.

This is not to say that microsecond intervals are actually available.  There is
something to be said for overspecifying the time interval.  If a finer clock
becomes available on a future machine it can be supported without having to
change the units in the software.
-- 
Bill Sebok			Princeton University, Astrophysics
{allegra,akgua,burl,cbosgd,decvax,ihnp4,noao,princeton,vax135}!astrovax!wls