Re: Hungry for hardware timers

Jaswinder Singh
2010-12-10T04:47:54Z

Hello,

On Tue, Sep 7, 2010 at 4:25 PM, Clemens Ladisch <clemens@ladisch.de> wrote:
> Jaswinder Singh Rajput wrote:
>> As per dmesg([    0.325958] hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0)
>> so IRQs are like this :
>> HPET T0 : 2
>> HPET T1 : 8
>> HPET T2 : 0
>
> "0" means that the BIOS did not initialize it.  In this case, the driver
> will initializes it when accessed, with the first supported IRQ above 15.
> On your HPET's T2, this is IRQ 20.
>

I have used /dev/hpet as periodic interrupt and it works great but
settings for HPET_T2_CMP will be like this :

10 micro-seconds : 110 /* 0.00001 sec */
100 micro-seconds : 1230 /* 0.0001 sec */
1 milli-second : 13800 /* 0.001 sec */
10 milli-seconds : 142580 /* 0.01 sec */
100 milli-seconds : 1431150 /* 0.1 sec */
1 second : 14317330 /* 1 sec */
10 seconds : 143179330 /* 10 sec */
100 seconds : 1431799400 /* 100 sec */

I do not have a oscilloscope so I am measuring it by using printks.
I am curious, Why it is irregular.

I am looking for one more timer interrupt handler, how can I get one
more interrupt handler for user.