Messages in this thread |  | | Date | Fri, 18 May 2001 08:32:33 -0400 (EDT) | From | Bart Trojanowski <> | Subject | Re: [newbie] timer in module |
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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.
> 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/
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