T2/T2+ busstat

The busstat tool can be a useful performance tuning aid, allowing one to drill into the load an application is placing on the memory sub-system. However, one note of caution, on the T2/T2+ the bank_busy_stalls counters should not be used, as erroneous results are returned – makes it looks like the application is causing bank busy stalls, even when this is not the case. Future revs of busstat are aware of this, but in the interim, this is a performance counter to ignore when tuning your app.

Comments:

The work around (from the bug report) is to use the rd_queue_latency counter. This counter includes all bank-busy stall cycles (plus other stalls).

Posted by Krishna Yenduri on August 15, 2008 at 04:59 AM PDT #

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Dr. Spracklen is a senior staff engineer in the Architecture Technology Group (Sun Microelectronics), that is focused on architecting and modeling next-generation SPARC processors. His current focus is hardware accelerators.

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