Re: [RFT] Please test rdtsc on various x86-64 hardware (app included)

[Linus Torvalds]

On Mon, Apr 18, 2011 at 12:32 PM, Andrew Lutomirski <luto@xxxxxxx> wrote:
>
> I've tested on Sandy Bridge, Allendale (i.e. Pentium Dual-Core),
> Bloomfield. and C2D.

Arrandale:

  CPU vendor   : GenuineIntel
  CPU model    : Intel(R) Core(TM) i5 CPU         670  @ 3.47GHz
  CPU stepping : 2
  TSC flags    : tsc rdtscp constant_tsc nonstop_tsc
  Using lfence_rdtsc because you have an Intel CPU
  Will test the "lfence;rdtsc" clock.
  Now test passed  : margin 98 with 71696816 samples
  Load3 test passed: margin 72 with 8926478 samples
  Load test passed : margin 88 with 14660759 samples
  Store test failed as expected: worst error 764 with 10784245 samples

but that wasn't very surprising since you already tested the
micro-architectures just around it.

On a dual-socket X5550 (master.kernel.org: 16 threads total: 4 cores
per socket, with HT):

  CPU vendor   : GenuineIntel
  CPU model    : Intel(R) Xeon(R) CPU           X5550  @ 2.67GHz
  CPU stepping : 5
  TSC flags    : tsc rdtscp constant_tsc nonstop_tsc
  Using lfence_rdtsc because you have an Intel CPU
  Will test the "lfence;rdtsc" clock.
  Now test passed  : margin 166 with 38875272 samples
  Load3 test passed: margin 235 with 2972261 samples
  Load test passed : margin 119 with 4409699 samples
  Store test failed as expected: worst error 2710 with 3764216 samples

Some opteron love would be good, but I don't have access to any right here.

                     Linus
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