On: Measuring CPU core-to-core latency

[jtorsella]

If anyone is interested, here are the results on my M1 Pro running Asahi Linux:

Min: 48.3 Max: 175.0 Mean: 133.0

I’ll try to copy the exact results once I have a browser on Asahi, but the general pattern is most pairs have >150ns and a few (0-1; 2-3,4,5; 3-4,5; 4-5; 6-7,8,9; 7-8,9; 8-9) are faster at about 50ns.

Edit: The results from c2clat (a little slower, but the format is nicer) are below.

CPU 0 1 2 3 4 5 6 7 8 9

   0    0   59  231  205  206  206  208  219  210  210

   1   59    0  205  215  207  207  209  209  210  210

   2  231  205    0   40   42   43  180  222  224  213

   3  205  215   40    0   43   43  212  222  213  213

   4  206  207   42   43    0   44  182  227  217  217

   5  206  207   43   43   44    0  215  215  217  217

   6  208  209  180  212  182  215    0   40   43   45

   7  219  209  222  222  227  215   40    0   43   43

   8  210  210  224  213  217  217   43   43    0   44

   9  210  210  213  213  217  217   45   43   44    0

[mrtksn → jtorsella]

M1 on Macbook air on macOS Ventura beta 7:

min/max/mean - 34.6ns/57.7ns/39.1ns

       0       1       2       3       4       5       6       7   
  0
  1   58±6 
  2   48±6    46±6 
  3   39±6    37±6    36±6 
  4   41±6    38±6    42±6    38±6 
  5   35±6    37±6    37±6    36±6    36±6 
  6   38±6    39±6    36±6    40±6    40±6    38±6 
  7   39±6    38±6    36±6    37±6    38±6    36±6    38±6

[nviennot → jtorsella]

It'd be great if you could provide the output.csv actually :D

I think there's a CLI tool for pastebin

[jtorsella → nviennot]

Done. Thanks for mentioning the paste service cli, had no idea and am definitely going to be using it!

[tbrock → jtorsella]

Would love to see what the results are for an m2.

[dimensi0nal → tbrock]

Showing latency=round-trip-time/2 in nanoseconds:

       0       1       2       3       4       5       6       7
  0
  1   46±4
  2   37±4    34±4
  3   37±3    38±4    38±3
  4   34±4    34±4    34±4    37±4
  5   37±4    37±4    37±4    34±4    34±4
  6   38±4    34±4    37±4    34±4    34±4    37±4
  7   37±4    34±4    37±4    37±4    38±4    37±4    34±4