Attached below an example code demonstration:
-----------------------
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/delay.h>
struct task_struct *kthread;
int thread(void *args)
{
while (!kthread_should_stop()) {
mdelay(5000);
printk(KERN_INFO "Hello!\n");
schedule(); /* To avoid hanging */
}
kthread = NULL;
do_exit(0);
}
static int __init hello_init(void)
{
kthread = kthread_create(thread, NULL, "test_mdelay");
if (IS_ERR(kthread))
printk(KERN_INFO "Error creating kthread\n");
else
wake_up_process(kthread);
return 0;
}
static void __exit hello_exit(void)
{
if (kthread)
kthread_stop(kthread);
}
module_init(hello_init);
module_exit(hello_exit);
MODULE_LICENSE("Dual BSD/GPL");
-----------------------
David Ramirez wrote:
> I've checked the wrong source version, mdelay() is implemented as:
>
> n = (loops_per_jiffy * HZ * usecs) / MILLION;
> for(i=0;i<n;i++)
> __asm__ __volatile__("rep;nop": : :"memory");
>
> Similar as it is in x86. But in UML it doesn't work for me.
>
>
> David Ramirez wrote:
>> Hi all,
>>
>> Recently, I decided to use UML to develope my modules. My module
>> calls mdelay() macro that is implemented in UML as:
>>
>> n = (loops_per_jiffy * HZ * usecs) / MILLION;
>> for(i=0;i<n;i++)
>> do ; while(0);
>>
>>
>> mdelay() worked perfectly in x86 but in UML it doesnt seem to sleep.
>>
>> I've checked loop values:
>>
>> loops_per_jiffy: 27918336
>> HZ: 100
>> MILLION: 1000000
>>
>> My system is:
>> linux 2.6.32-r5
>> gcc version 4.3.4 (Debian 4.3.4-2)
>>
>> Can it be a compiler optimization?
>>
>> Thanks in advance,
>> David
>>
>>
>>
>
>
------------------------------------------------------------------------------
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