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SubjectRe: [newbie] timer in module
Le Fri, 18 May 2001 08:32:33 -0400 (EDT)
Bart Trojanowski <bart@jukie.net> a ecrit :

> On Fri, 18 May 2001, sebastien person wrote:
>
> > I have a network module that need to regularly get data from network
> > adaptater.
> > But I don't know if it safe to do a loop with a timer in the module.
>
> First off you have to decide where you want to run your 'get data'.
There
> are three context you can pick from: user priority or from the kernel.
If
> you run the loop below from a user context then you will have a very
> unresponsive system but at least other things will still run. If you
run
> that from a kernel context nothing else will run... unless you
explicitly
> call the scheduler.

So the fact to call the scheduler allow me to handle send request for
example ?

>
> > My aim is to do a get data call every x seconds (x is variable).
>
> You mentioned a timer... it runs in kernel context but at least it
> will not end up hanging your system up. This is how you would use one:
>
> struct tq_struct timer;
> init_timer(&timer);
> timer.routine = func;
> timer.data = something;
> mod_timer(&timer, 5*HZ); // 5 seconds from now
>
> void func( unsigned long something ) {
> get_data( something );
> mod_timer(&timer, 5*HZ); // again in 5 seconds
> }
>
> Make sure you call 'del_timer_sync' once you are done.
>
> > Is it better to let an external program executing timer call and get
data
> > call via ioctl ?
>
> Since you are getting data every 5 seconds you may as well use a user
> space program. It does not seem like you are looking for phenomenal
> responsiveness here.
>
> Bart.
>
> --
> WebSig: http://www.jukie.net/~bart/sig/

Thanks for all these details
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