Xref: utzoo comp.dcom.modems:2600 comp.mail.uucp:2083
Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!decwrl!labrea!rutgers!uwvax!oddjob!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.dcom.modems,comp.mail.uucp
Subject: Re: UUCP g stats
Message-ID: <13858@mimsy.UUCP>
Date: 4 Oct 88 19:10:36 GMT
References: <183@arnold.UUCP> <1988Sep20.184054.2403@utzoo.uucp> <184@arnold.UUCP> <21254@watmath.waterloo.edu>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 25

>In article <201@arnold.UUCP> dave@arnold.UUCP (Dave Arnold) asks
>>where the bottleneck on the VAX is?

In article <21254@watmath.waterloo.edu> egisin@watmath.waterloo.edu
(Eric Gisin) writes:
>Lack of CPU power mostly.

And inefficiency:

>The BSD tty device drivers passes input characters one-at-a-time
>to the line drivers through the line switch l_rint (receiver interrupt)
>function.
>The expensive calling convention on the VAX makes things worse here.

Just as bad, each input character is passed to the reading program
one at a time through ureadc().

We have been reluctant to fix either of these mainly for two reasons:
The old tty code is both large and fragile; and we would like to
replace the line-switch structure with something like Streams (not
STREAMS).  The latter mandates redoing the code in enough places that
fixing the one-at-a-time business will be trivial :-) .
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris