I am starting to learn signal handling in Linux and have been trying out some simple codes to deal with SIGALRM. The code shown below sets a timer to count down. When the timer is finished a SIGALRM is produced. The handler for the signal just increments a variable called count. This is repeated until the user hits ‘q’ in the keyboard. The code is shown below:
The problem I am facing is this, when I set the timer for 1000000usec it works fine (i.e 1sec). However if I keep reducing the usec time to 100000, 10000, 1000 etc the timing seems to be too slow. The count variable is not being incremented as fast as it should be. Why is this? I have a hunch I am doing some silly mistake here but I am not sure what it is.
Any help would be greatly appreciated.
Hi,
Just a thought but i might be totally wrong/out of subject: i suspect it has to do with linux timer resolution which is at 10ms (or not?) so no matter how small you set your interval your code will only be ran every 10ms ...
PS.: You query remind me of a "nice surprise" when i was working with timer on linux
HI,
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Hi guys,
this is my first posting, so at first hi to everyone! ;)
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hi friends i have a problem in signal handling ...
let me explain my problem clearly..
i have four process ..
main process forks two child process and each child process again forks another new process respectively...
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Discussion started by: senvenugopal
2 Replies
LEARN ABOUT LINUX
sleep
SLEEP(3) Linux Programmer's Manual SLEEP(3)NAME
sleep - Sleep for the specified number of seconds
SYNOPSIS
#include <unistd.h>
unsigned int sleep(unsigned int seconds);
DESCRIPTION
sleep() makes the calling thread sleep until seconds seconds have elapsed or a signal arrives which is not ignored.
RETURN VALUE
Zero if the requested time has elapsed, or the number of seconds left to sleep, if the call was interrupted by a signal handler.
CONFORMING TO
POSIX.1-2001.
BUGS
sleep() may be implemented using SIGALRM; mixing calls to alarm(2) and sleep() is a bad idea.
Using longjmp(3) from a signal handler or modifying the handling of SIGALRM while sleeping will cause undefined results.
SEE ALSO alarm(2), nanosleep(2), signal(2), signal(7)COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2010-02-03 SLEEP(3)