[ltt-dev] Bug in LTTv statistics ?

[Mathieu Desnoyers]

* François Godin (copelnug at gmail.com) wrote:
> I think I've found another bug in the LTTv statistics. The problem is with
> page_fault_entry event. In the textdump they are classified as being in mode
> TRAP but they appear in SYSCALL and USER_MODE mode in the statistics view.

This comes from the way callbacks are dealt with in the priority hook
list:

When an event is encountered, the statistics "before" event callbacks
are called first, then the state "before" event callbacks are called,
then the event callbacks per se (e.g. textdump) are called, and then the
after state, followed by after stats hooks.

So given that the statistics hooks are called before the state
modification, and that the textdump hooks are called after the state
modification, there is a discrepancy between the two. But in reality,
the statistic hook has the correct state associated (the trap occurs its
calling context, not in "itself"). But how to fix the textdump is
unclear to me.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com