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From: honey@down.FUN (code 101)
Newsgroups: net.bugs.uucp
Subject: Re: 4.2 uucp performance problems?
Message-ID: <443@down.FUN>
Date: Mon, 11-Feb-85 22:44:15 EST
Article-I.D.: down.443
Posted: Mon Feb 11 22:44:15 1985
Date-Received: Tue, 12-Feb-85 06:39:45 EST
References: <438@down.FUN> <548@vortex.UUCP>
Organization: Princeton University, EECS
Lines: 22

i recommend the pkspeedup code for all versions of uucp and
unix, at all baudrates.  it is simply the correct thing to do.

lauren and others have observed that short reads are more
frequent in 4.2.  the obvious conclusion is that 4.2 has a
smaller system call overhead, but this goes against my
religion.  in any case, we have ample evidence that the speedup
is useful in 4.2: mark plotnick tested a number of cases and
pkspeedup beat them all on throughput *and* cpu overhead.

some versions of uucp use the system v VMIN/VTIME trick; as
such, the pkspeedup line will usually not be reached.  on those
(rare) instances when the read returns short, pkspeedup remains
the best thing to do.

v7 based systems (e.g. 4.1bsd) don't have VMIN.  v8 has a
buffering line discpline that you push on top of of the ld
stack; this makes it look look vaguely like the system v VMIN.

i posted a 4.2 nap() here the other day (today?).  i have seen
nap() hacks for other unix versions in net.sources in the past
-- consult net.wanted.sources.