6 ms·

Intel CPU Die Topology

• dan-robertson 3y ago
  Why is the rtt measured here on canon lake so asymmetric? I would have expected symmetry along the leading diagonal.
  • jeffbee 3y ago
    And why is core 0 magical on that machine?
    • jcranmer 3y ago
      IIRC, core 0 is the one that tends to service processor interrupts, which may mean that the data is unusually noisy in a way that tends to underestimate the RTT latency time.
      • jeffbee 3y ago
        There’s a similar weird artifact at index 64.
        • innocenat 3y ago
          Core 64 is the hyper-threaded pair of core 0.
          • jeffbee 3y ago
            Not on that machine. That would only be true on a 128-thread system, but this one has 96 threads.
  • yvdriess 3y ago
    Speculation, but could it be because of a ring topology?
• lincpa 3y ago
  [dead]
• Cockbrand 3y ago
  This might be a nitpick, but it seems like already the intro sentence isn't factually accurate: > Over the past 10-15 years, per-core throughput slowed down I assume that the author meant that the acceleration of per-core throughput over time has slowed down, not the throughput itself.
• _a_a_a_ 3y ago
  > Over the past 10-15 years, per-core throughput slowed down throughput of what?