[ltt-dev] Bug in LTTv statistics ?
copelnug at gmail.com
Fri Jul 16 09:35:13 EDT 2010
Thank for the answer. That made it clear but it bring others questions :
Is the state for the "page_fault_entry" event is the previous state of the
cpu ? I suppose but a confirmation would be welcome.
I try to understand why on one trace, is there still "page_fault_entry" in
TRAP mode. I checked the previous correction, and while it find the right
states for all events except those that LTTv put in "TRAP" mode. Am I
missing something else or is it a glitch in LTTv?
2010/7/15 Mathieu Desnoyers <compudj at krystal.dyndns.org>
> * François Godin (copelnug at gmail.com) wrote:
> > I think I've found another bug in the LTTv statistics. The problem is
> > page_fault_entry event. In the textdump they are classified as being in
> > TRAP but they appear in SYSCALL and USER_MODE mode in the statistics
> This comes from the way callbacks are dealt with in the priority hook
> 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.
> Mathieu Desnoyers
> Operating System Efficiency R&D Consultant
> EfficiOS Inc.
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