Intel CPU Die Topology

Re:Intel CPU Die Topology by dan-robertson on Sunday May 28, 2023 @06:17AM (#36102756)

Why is the rtt measured here on canon lake so asymmetric? I would have expected symmetry along the leading diagonal.

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Re:Intel CPU Die Topology by jeffbee on Sunday May 28, 2023 @09:21AM (#36103759)

And why is core 0 magical on that machine?

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Re:Intel CPU Die Topology by jcranmer on Sunday May 28, 2023 @10:18AM (#36104193)

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.

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Re:Intel CPU Die Topology by jeffbee on Sunday May 28, 2023 @10:35AM (#36104335)

There’s a similar weird artifact at index 64.

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Re:Intel CPU Die Topology by innocenat on Sunday May 28, 2023 @12:05PM (#36105261)

Core 64 is the hyper-threaded pair of core 0.

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Re:Intel CPU Die Topology by jeffbee on Sunday May 28, 2023 @02:34PM (#36106552)

Not on that machine. That would only be true on a 128-thread system, but this one has 96 threads.

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Re:Intel CPU Die Topology by yvdriess on Sunday May 28, 2023 @10:37AM (#36104350)

Speculation, but could it be because of a ring topology?

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