Debabrata Debroy wrote:
> I have written Following program so that fun() gets called by every 10 mili
> seconds.But after executing the program I Found its calling the function
> after 20 mili seconds.If I specify timeinterval as 20 mili second in
> XtAppAddTimeOut function its calling fun method after 30 mili seconds.
I don't believe there's any guarantee on XtAppAddTimeOut returning
after exactly the number of milliseconds specified - especially on busy
systems it may take longer than that to get scheduled again.
I suspect what you're seeing is simply the effect of the system timer
resolution being 10 ms by default. Since your code takes a non-zero
amount of time to run, by the time it's complete, waiting for at least
20ms puts you to the tick that's 30ms after when you started:
start + 0ms: Previous timeout expires, scheduler queues
your process to run, XtAppMainLoop searches
timeouts to see what's up, finds your timer
has expired and calls your callback function
start + 0.1ms?: Your code starts running
start + 0.2ms?: Your code sets a timeout to occur in 20ms,
which would be start + 20.2ms, so it's
scheduled for the first tick after that,
which would be start + 30ms.
You can probably find other people running into this with select()/poll(),
certainly I've found bugs in the database that they filed and were closed
as "Not a bug".
I believe Linux defaults to a higher resolution timer, something you can
enable system-wide on Solaris, but if you're shipping this code to customers,
forcing them to modify it on all their systems is not a very good plan.
If your app is so timing senstive that 10ms makes a difference, you probably
want to use a more modern/supported API than libXt for your timeouts. Xt
is only recommended when using a legacy toolkit such as Motif these days.
BTW, this is all from memory & a quick glance at the bug database - if you want
someone to actually investigate, you should open a support call, not rely on a
post to a free discussion forum.
--
-Alan Coopersmith- alan.coopersm...@oracle.com
Oracle Solaris Platform Engineering: X Window System
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