how to measure IRQ service latency

[loody]

hi:

2010/12/22 neependra.khare at gmail.com <neependra.khare at gmail.com>:
>
>
> On Wed, Dec 22, 2010 at 5:30 PM, Pradeep Kumar <pradeepkernel at gmail.com>
> wrote:
>>
>> hi,
>>     can any one suggest a way to measure IRQ service latency? .
>
> I believe you can measure it with Ftrace. You might need to use irqsoff
> tracer.
> For reference:-
> http://people.redhat.com/srostedt/
I go into the website and see a lot of files with suffix odp.
is there any document which can tell us how to use it?
sincerely,
miloody