Miscellaneous Machine Notes

Blue Gene/P at Argonne

• ​ALCF pages
• PAPI 3.0.9 was ported and installed by IBM in the usual location: /soft/apps/papi-c-3.0.9
  • true 64-bit counters in BG/P and all counters for PAPI always starting from a true zero (no write allowed)
  • 455 total native counters, max multiplexing: 256
  • Implementation details: The BG/P hardware performance counters are the values of special CPU registers. Each 64-bit counter is split into a 12-bit low-order portion and a 52-bit high-order portion. Implemented as SRAM array, the high-order logic sequentially polls the low-order counters and increments an SRAM word if the overflow bit of the corresponding low-order counter is set. Each counter can be configured to generate an interrupt if a specified threshold value is reached.
• PAPI counter tests:
  • available PAPI counters (not including native)
  • native BGP counters