Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!harpo!seismo!hao!hplabs!sri-unix!drockwel@bbn-vax From: drockwel@bbn-vax@sri-unix.UUCP Newsgroups: net.unix-wizards Subject: Re: Why is the "real time" so much greater than the "cpu time" Message-ID: <3142@sri-arpa.UUCP> Date: Fri, 15-Jul-83 23:54:00 EDT Article-I.D.: sri-arpa.3142 Posted: Fri Jul 15 23:54:00 1983 Date-Received: Sun, 17-Jul-83 17:02:16 EDT Lines: 14 From: Dennis RockwellYour question indicates a basic misapprehension: both the "user time" and the "sys time" given by the time command are CPU times. The user time is that time spent in your program, and the sys time is the time the operating system spent supporting your program. Thus, if your "user time" is close to the "real time", then your system is pretty well tuned, at least for CPU-bound processes. Of course, the terms I used above are subject to quantization errors; to be more accurate, the CPU times are the proportion of the times that the clock ticked while your program had control of the CPU. IO time gets added in (as sys time); also, if the clock ticks while the system is servicing a device interrupt, that time gets added to yours, even if the device that interrupted has nothing to do with you.