0 Replies Latest reply on Nov 17, 2010 8:21 AM by jreybert

    L3 cache events for new processors

    jreybert

      Hello,

       

      I am trying to trace L3 cache behaviour for two different architectures, and I encounter a lot of difficulties.

       

      These two architectures are based on X7460 and X7560 Intel Xeon processors.

       

      I am using VTune 9.1 and PTU 4.0 Update 3 to sample the events.

       

      PTU gives me a list of available events for each architecture.

       

      For the X7400 series, I have many many events about L1 and L2 caches access (load, store, self, both_cores, demand, prefetch). Actually, 30% of the available events are about cache. But NOTHING about L3 cache.

       

      For the X7500 series, I have some LLC (last level cache) events:

      MEM_LOAD_RETIRED.LLC_MISS
      MEM_LOAD_RETIRED.LLC_UNSHARED_HIT

       

      and a lot about LLC in OFFCORE_RESPONSE_0 events. But nothing clearly mentionning store or load...

       

      My questions are:

       

      • are the L3 cache events exist? Is it just PTU and VTune which do not know where to search, and it is possible to physically interrogate some registers? Or L3 caches are too complicated now, and Intel just dropped the L3 cache evaluation?
      • Since which architecture the L3 are sorely accessible?

       

      Thanks

       

      Jérôme