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From: howie@cunixc.columbia.edu (Howie Kaye)
Newsgroups: comp.unix.ultrix
Subject: Re: Why Ultrix C library is slow
Message-ID: <10276@felix.UUCP>
Date: Fri, 23-Oct-87 13:32:00 EST
Article-I.D.: felix.10276
Posted: Fri Oct 23 13:32:00 1987
Date-Received: Mon, 26-Oct-87 00:49:29 EST
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Organization: Columbia University
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I was working on the 4.3 ndbm'ized passwd routines and recompiled
ls(1) with them.  We then timed ls both (old and new) to see what kind
of improvement this would lead to.  We tried out a pretty much "worst
case" scenario:

	time /bin/ls -l /u/student

where each of the 1878 directories had a different owner, all were
near the end of the passwd file, and a lot of uid's not in the passwd
file.

Here are the results:

	4.3:				Ultrix:

real	1m14.98s		real	28m49.10s
user	0m4.18s			user	13m34.71s
sys	0m12.38s		sys	0m49.38s


We thought this was pretty drastic.  29 minutes to do an ls -l, vs
1.25 minutes.  It turns out that besides the basic speedup of using
ndbm instead of the sequential passwd file, the Ultrix getpwuid/getpwnam 
routines make calls to try and get the passwd info off of yp.  Since
we aren't running yp, that seemed to be a bit of a waste.  

With 1300 entries in our /etc/passwd file, we are switching to a 4.3
passwd scheme.   Most of the programs which seemed to be slow seem
that way because they access the passwd file in "bad" ways.

------------------------------------------------------------
Howie Kaye				howie@columbia.edu
Columbia University 			hlkcu@cuvma.bitnet
Systems Group				...!rutgers!columbia!howie