interrupt latency

[Muni Sekhar]

Hi All,

I used the Linux kernel’s ‘Ftrace’ framework for tracing the interrupt
latencies.

Sometimes I noticed a delay(time between do_IRQ() to start of ISR())
in start of ISR(interrupt service routine) to execute , some other
times I noticed ISR execution time(entering and exiting a function) is
very high.

I’d like to know in which scenarios, ISR gets executed lately?

In which scenarios, ISR execution time is very high?

Can someone please clarify me on this.

-- 
Thanks,
Sekhar