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 DEBIAN
signal
signal(3tcl)signal(3tcl)NAME
signal - dynamically loadable signal handling for Tcl/Tk
SYNOPSIS
signal (add|delete|print|version) [options]
COMMANDS
add signo proc [-async]
Adds a signal handler for signal signo through proc proc. Signals can be provided by number, or the most common ones are provided by name
(e.g., SIGHUP). The proc is any Tcl procedure, and it is evaluated when the signal comes in. It will be provided no arguments.
Signal handlers have Posix semantics - they persist until reset.
If -async is used, the signal handler is created using Tcl_AsyncCreate(). Checks for the signal are very frequent (each evaluation) using
this technique, but one doesn't know quite where evaluation is or how to handle errors in this situation. The code will evaluate the pro-
vided procedure in the current interpreter if available, and in the interpreter which added the signal handler otherwise. At least until a
better scheme is suggested.
The -async is especially useful to interrupt "runaway" procs, or to cause a quick exit; the default mechanism simply waits for another
MainLoop cycle.
signal delete signo
Restores handling of signal signo to the default ( SIG_DFL ).
signal print
Prints the handling of all signals with handlers. Formatted as
signal ----> procedure or as
signal !---> procedure
if the signal is handled asynchronously
signal print signo
Prints the procedure for handling signal signo. Prints the word UNHANDLED if no signal handler is active for that signal.
signal version
Returns the string representing the current version of the package
AUTHOR
Michael Schwartz <mschwart@nyx.net>. Tilman Kranz <tilde@tk-sls.de> patched this for wider portability on Linux
Tcl Signal Extension 1.4.0.1 Tcl signal(3tcl)