Re: Sleeping

Eberhard Moenkeberg (
7 Sep 1996 17:06:42 GMT

Colten Edwards ( wrote:

: I haven't been able to find this anywhere, but I need to know what a good
: way to sleep within a kernel module is. I found something called
: lcdpanel-0.50.tar.gz on sunsite and have made the LCD device and compiled
: the module, but I noticed that the module uses for (t=0; t <3000; t++) ;
: for sleeping which is not a good way to wait in the kernel, so I'd like
: to replace it. I tried usleep but that's a lib function so is unsuitable.
: The function is called thusly,

: static int lcd_write (struct inode *inode, struct file *file, const char
: *buf, int count)

3000 times t++ is fairly short these days.
If your time is long enough, you can do something like:

* kernel mode waiting, time unit is jiffy (10 ms)
static void jiffy_sleep(u_int time)
current->state = TASK_INTERRUPTIBLE;
current->timeout = jiffies + time;

The task gets re-scheduled if the time has elapsed.
Calling it with 0 gives an indefinite short time, just allowing
other kernel mode tasks to get the CPU.

Cheers -e

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