FreeBSD内核模块中的Timer？

Question

I'd like to let my kernel module periodically do something (a certain time interval, like 10 sec) in FreeBSD kernel. Any example for doing that?

I searched and found that there are functions like callout/timeout(old), but they seem complicated, and I cannot find good examples for them. For callout'', it seems that callout_reset'' is similar to the function I want (arguments include a handler and a time interval). But it seems to only execute once. So I'm confused.

Examples are the best, even for function ``timeout''.

Answer 1

You need to use callout(9). As for examples... Hm, for a real-world code you could take a look at this: http://svnweb.freebsd.org/base/head/sys/dev/iscsi/iscsi.c?revision=275925&view=markup ; search for is_callout. Basically, you need 'struct timeout', a function that will get called periodically, and then you need to get the timer ticking:

struct callout callout;

static void
callout_handler(void *whatever)
{
        // do your stuff, and make sure to get called again after 'seconds'.
        callout_schedule(&callout, seconds * hz);
}

static void
start_ticking(void)
{
        callout_init(&callout, 1);
        callout_reset(&callout, seconds * hz, callout_handler, whatever);
}