profiling functions called in interrupt context

[Amit Nagal]

Hi ,

i want to measure time spend in a callback function called from
interrupt context .
since the time spend will be in us / ns , what kernel apis can i use
to measure it ?

also since i want to use it in interrupt context  , kernel time
measurement apis should not sleep .
i am using embedded arm target , and tools like OProfile  are not available .

can i be guided which  kernel time measurement apis shall i use to
measure time in a interrupt callback ?

Regards
Amit Nagal