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time command bug in next headers?
- X-seq: zsh-workers 2522
- From: Robert F Tobler <rft@xxxxxxxxxxxxxxxxxxxxx>
- To: Zsh Workers <zsh-workers@xxxxxxxxxxxxxxx>
- Subject: time command bug in next headers?
- Date: Mon, 2 Dec 96 23:33:00 +0100
- Original-received: by NeXT.Mailer (1.118.2)
- Pp-warning: Illegal Received field on preceding line
- Reply-to: rft@xxxxxxxxxxxxxxxxxxxxx
I am working on an i686-next-nextstep3.3 system. I have noticed that the
system time as reported by is different from the times I get using the
'getrusage' system call. I tracked the problem down to the fact that the
Nextstep headers seem to lie about the value of CLK_TCK. They tell zsh,
CLK_TCK is 64, but the man pages and comparison with the times reported by
'getrusage' say its 60.
I have checked on my m68k-next-nextstep3.3 system, and this exhibits the same
problem. On both machines I compiled zsh using gcc, therefore it might also
be a problem with gcc's handling of system headers, but I don't think so since
the header file in question (bsd/time.h) is only marginally modified by gcc
(#undef NULL is inserted somewhere).
If somebody else has also noticed this problem on Nextstep systems (e.g by
setting REPORTTIME=1 and timing command with /bin/time as well; you'll then
get both timings and see the difference), I'd request you ignore the Nextstep
headers and set the value of clktck in jobs.c to 60. (#ifdef NeXT).
Now. in a similar vein I have a few questions: there are a number of
different system call interfaces for getting the user and system time of the
process:
times(...)
vtimes(....)
getrusage(...)
What are the advantages and disadvantages of all these interfaces with respect
to portability, overhead, and time resolution? On Nextstep at least it seems
as if the getrusage(...) interface has a resolution of 1/100 of a second
whereas times only has 1/60 sec resolution.
------------------------------------------------------------------------
Robert F. Tobler - tel:+43(1)58801-4585,fax:5874932
Institute of Computer Graphics - mailto:rft@xxxxxxxxxxxxxxx
Vienna University of Technology - http://www.cg.tuwien.ac.at/~rft/
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