> > > When I added a modified version of check_scheduability() to the uncore > > component it now detects that the two events with constraint conflicts > > cannot be used together. This allows PAPI to return an error at add > > event time which is better than reporting it when trying to read the > > results after the test is completed. > > It's odd this is failing though. Which events are causing the issue? > It sounds like a bug in the uncore constraint code. >
We have now identified two different pairs of events that get this problem. They are: snbep_unc_cbo0::UNC_C_TOR_INSERTS:MISS_ALL:cpu=0 snbep_unc_cbo0::UNC_C_TOR_INSERTS:NID_MISS_ALL:nf=0x1:cpu=0 and snbep_unc_cbo0::UNC_C_LLC_LOOKUP:ANY:cpu=0 snbep_unc_cbo0::UNC_C_TOR_INSERTS:MISS_ALL:cpu=0 Based on information in the libpfm4 event tables, the first pair should fail because the same event is using two different masks from the same mask group. The masks in this mask group are marked as INTEL_X86_NCOMBO which says that "unit masks within the group cannot be combined". But the second pair of events are different events so there should not be a mask conflict. Each of these events have a counter mask constraint of 0x3 which means that there should be enough counters to use these two events together. The check_scheduleability() test (enable/disable/read) also fails for this pair of events. > If you can reproduce the issue using the "perf" tool then you can probably > get the kernel developer's attention. > I will try using these events with perf. It is not my favorite tool but if it will either show that these events should work together or help convince others that something in the kernel is not working correctly, it is worth the effort. Gary ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ _______________________________________________ perfmon2-devel mailing list perfmon2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
