Hi,

We recently discovered some problems with the perfmon code in 2.4.7 and
probably all older kernels. 

The counts reported by the API are incorrect if the monitored process
was context-switched during its execution. More or less the counts
would be double of what they should be. 

Also we fixed a problem that was affecting people doing DATA EARS. 
The content of some PMD14-PMD17 was not saved and restored on context-switch
due to an error in the perfmon initialization code where, somehow, the
number of PMDs and PMCs reported by PAL got swapped.

This patches fixes both problems. As a results, events which are
not likely not to change between runs of fairly deterministic programs
are much more stable (like LOADS_RETIRED or IA64_INST_RETIRED, for instance).


Also note that, if you have downloaded pfmon-0.06 from ftp.hpl.hp.com
since June 5th,2001, do not trust the results it gives. Under certain
event configurations, it will swap results between counters. This should
be fixed in an intermediate 0.06a release which should be out this week.


-- 
-Stephane