I have a homework problem that I'm working on tonight that I don't have the faintest idea how to approach! Please help! The problem says:
Write a program that uses library functions "sleep" and "times" to determine the approximate number of clock ticks per second.
I appreciate the help!
Clock ticks per second means process clock ticks?
Basically what you need to do is measure how much time elapses when it sleeps for a second.
Originally Posted by Adak
Okay so I use a line like sleep(1000) to stop the process for 1 second. How do I use the "times" function to measure the time that elapses?
There are several depending on what you need. C has a function called clock.
I looked at that one but the problem is pretty specific. I need to use a library function called times. I looked at the man page but I am SO new to linux and C it isn't funny. More help?
There is no function called times in C. Of Linux API I know nothing since I don't use Linux.
In that case you'll need to wait until someone who has the knowledge pops up or if you can find the function on your own.
times() will give you the time used by the processor.
http://www.hmug.org/man/3/times.php
sleep() will allow you to specify time that the process sleeps.
I'm not entirely sure how you combine those to get the tick-length tho'.
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Mats
Compilers can produce warnings - make the compiler programmers happy: Use them!
Please don't PM me for help - and no, I don't do help over instant messengers.
Pretty simple -- times() fills in a structure that looks like this:
These numbers are in units of "ticks." The total time spent is the sum of tms_utime and tms_stime. Divide this by a number in seconds, and you get ticks per second.Code:struct tms { clock_t tms_utime; /* user time */ clock_t tms_stime; /* system time */ clock_t tms_cutime; /* user time of children */ clock_t tms_cstime; /* system time of children */ };
So I would suggest calling times() to get a start value. Then call sleep(10) (or some other amount), then call times() again. Take the difference in the ticks, and divide by how many seconds you slept.
This seems kind of fishy though -- do tms_utime and tms_stime really increment during sleeping? I would have thought not, but presumably the instructor knows something I don't.
tms_utime and tms_stime should not increment during a sleep.
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Mats
Compilers can produce warnings - make the compiler programmers happy: Use them!
Please don't PM me for help - and no, I don't do help over instant messengers.
