2010/7/16 Mathieu Desnoyers <[email protected]> > * François Godin ([email protected]) wrote: > > 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. > > Well, in reality, the page fault entry event is recorded in page fault > context. So the textdump has it right. But that's really just a > "modeling artefact" to have one or the other. >
Ok, but I need to know how the mode is found in LTTv stats to allow me to compare two solutions. Then once I got it right, I can switch back to being compatible with the textdump. Is my assumption correct ? > > > > 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? > > No sure what you mean. Can you try to explain a little more ? > I've made tests to verify my assumption. I load textdump in a custom parser and it give me the mode of the "page_fault_entry" events. I then compare the total of each mode to the number of "page_fault_entry" in each mode in the statistics view. For one trace, the result was perfect but for another trace, my parser didn't find any "page_fault_entry" events in the "TRAP" mode like LTTv stats did. The others mode had the right total except one whose total given by the parser was the one given by LTTv + the "page fault_entry" in TRAP. Page_fault_entry by mode: LTTv Parser 1 1 MODE_UNKNOWN 971 999 USER_MODE 999(parser) = 971(LTTv) +28(LTTv-TRAP) 26 26 SYSCALL 28 0 TRAP I've also made another discovery. It seems that the time between the "page_fault_entry" or "page_fault_exit" and the previous event is never added in the CPU_TIME. Is this intended? > > > > > > > > > > > 2010/7/15 Mathieu Desnoyers <[email protected]> > > > > > * François Godin ([email protected]) 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 > > > > > > > > > > > -- > > François Godin > > -- > Mathieu Desnoyers > Operating System Efficiency R&D Consultant > EfficiOS Inc. > http://www.efficios.com > -- François Godin
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