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From: ALMQUIST@SU-SCORE.ARPA
Newsgroups: net.unix
Subject: Re: 4.1bsd accounting question
Message-ID: <17296@sri-arpa.UUCP>
Date: Wed, 7-Mar-84 19:29:00 EST
Article-I.D.: sri-arpa.17296
Posted: Wed Mar  7 19:29:00 1984
Date-Received: Sat, 10-Mar-84 08:15:37 EST
Lines: 14

From:  Philip Almquist 

	I've never tried to do such analysis on a UNIX system, but such
problems (user time + system time /= real time) seems to be quite common.
Under Tops-20, for example, the sum of user time and system time seems to
vary between about 70% and 115% of real time.  The reasons seem to be both
due to numerical (rounding) problems and to data collection problems (some
time is counted as both kinds or not at all).  Solving the latter problem
is actually a rather subtle task, since you need an atomic way of
switching which clock you are charging the time to and since there are a
great many places where the average OS can switch between "user tasks" and
"system tasks".
					Philip
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