interpret the result of perf stat

[Zheng Da]

Hello,

I start to use perf to profile my program, but I'm not quite sure if I
understand some events.
First, perf can profile bus cycles. Is it the bus cycles of FSB?
Second, what is task clock? It seems to me that task clock is the
ticks used by a process. It should include the ticks used in the
kernel mode and the user space mode, as long as it is used in the
context of the process. I suppose it doesn't count the cycles used by
the interrupts such as page faults and softirq, even though the irqs
are caused by the process. Is it correct?

Thanks,
Da