* jiffies doesn't increase while doing mdelay() ?
[not found] <60bb95410603292150r6448596clbef348e1bededdaf@mail.gmail.com>
@ 2006-03-30 5:52 ` James Yu
2006-03-30 13:23 ` Arjan van de Ven
0 siblings, 1 reply; 2+ messages in thread
From: James Yu @ 2006-03-30 5:52 UTC (permalink / raw)
To: linux-kernel
Dear all,
I am doing the following in a kernel thread :
===== code segment=====
prink("before mdelay:%d, ", jiffies);
mdelay(300); // delay 300ms
printk("after mdelay:%d\n", jiffies);
===== code segment=====
However, jiffies before and after doing mdelay are the same!!!
Can someone please explain why jiffies doesn't change ?
Cheers,
--
James
cyu021@gmail.com
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: jiffies doesn't increase while doing mdelay() ?
2006-03-30 5:52 ` jiffies doesn't increase while doing mdelay() ? James Yu
@ 2006-03-30 13:23 ` Arjan van de Ven
0 siblings, 0 replies; 2+ messages in thread
From: Arjan van de Ven @ 2006-03-30 13:23 UTC (permalink / raw)
To: James Yu; +Cc: linux-kernel
On Thu, 2006-03-30 at 13:52 +0800, James Yu wrote:
> Dear all,
>
> I am doing the following in a kernel thread :
>
> ===== code segment=====
> prink("before mdelay:%d, ", jiffies);
> mdelay(300); // delay 300ms
> printk("after mdelay:%d\n", jiffies);
> ===== code segment=====
>
> However, jiffies before and after doing mdelay are the same!!!
> Can someone please explain why jiffies doesn't change ?
first of all you should use msleep() not mdelay() for such long
delays...
second if you have interrupts disables (for example via
spin_lock_irqsave) this is normal (and the reason why your code is
evil): The timer interrupt that normally increments jiffies can't happen
because you disabled it..
^ permalink raw reply [flat|nested] 2+ messages in thread
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[not found] <60bb95410603292150r6448596clbef348e1bededdaf@mail.gmail.com>
2006-03-30 5:52 ` jiffies doesn't increase while doing mdelay() ? James Yu
2006-03-30 13:23 ` Arjan van de Ven
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