Clarification upon stats

[sockstat <sockstat () hotmail com>]

Hi Everyone,

I wanted to ask about the performance counters that snort maintains. In the function detection_option_tree_evaluate you 
start maintaining ruleOTNEvalPerfStats using a macro. But this actually kicks in for any type of node while only the 
leaf nodes seem to be an OTN. It also adds up when a node type is Flow or pcre etc so maybe it should better be called 
ruleNODEEvalPerfStats? In detection_option_tree_evaluate you call detection_option_node_evaluate which in case of a 
leaf node gets the RTN from the OTN and fpEvalRTN is called where you maintain ruleRTNEvalPerfStats. So in the end 
screen where you print the stats out it seems to me that the microseconds for rule tree eval contain the rtn eval 
microseconds, because fpEvalRTN is called while counting the clock ticks for ruleOTNEvalPerfStats. In profile.c you 
print the amount of microseconds out. So rule tree eval is not just the ticks spent in detection_option_tree_evaluate, 
It has the clock ticks spent in fpEvalRTN included, while rtn eval is printed out sperately. 

Same thing holds for the mpse stats when __process_queue calls rule_tree_match, then the ticks spent in 
detection_oprion_tree_evaluate and fpEvalRTN are included in the ticks spent in mpseSearch. Hence it seems there is 
some overlap in the stats, because I don't see the ticks spent in fpEvalRTN subtracted from the amount of ticks spent 
in detection_option_tree_evaluate for example or did I miss this?

Also in case of a core 2duo CPU the tsc isn't stable and hence the calculation of how many clock ticks occur per 
microsecond might not be accurate?
Thanks, Reinoud.

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