ltt/branches/poly/doc/developer/lttng-atomic-up.txt

   1
   2 Atomic UP test results.
   3
   4
   5
   6
   7 using test-time-probe2.ko
   8
   9 Clock speed : cpu MHz         : 3000.077
  10
  11 Tracing inactive
  12
  13 [  125.787229] test init
  14 [  125.787303] test results : time per probe
  15 [  125.787306] number of loops : 20000
  16 [  125.787309] total time : 204413
  17 [  125.787312] test end
  18 [  175.660402] test init
  19 [  175.660475] test results : time per probe
  20 [  175.660479] number of loops : 20000
  21 [  175.660482] total time : 203468
  22 [  175.660484] test end
  23 [  179.337362] test init
  24 [  179.337436] test results : time per probe
  25 [  179.337440] number of loops : 20000
  26 [  179.337443] total time : 204757
  27 [  179.337446] test end
  28
  29 Res : 10.21 cycles per loop
  30
  31 Atomic UP, one trace, flight recorder.
  32
  33 [  357.983971] test init
  34 [  357.988837] test results : time per probe
  35 [  357.988843] number of loops : 20000
  36 [  357.988846] total time : 12349013
  37 [  357.988849] test end
  38 [  358.718896] test init
  39 [  358.723049] test results : time per probe
  40 [  358.723053] number of loops : 20000
  41 [  358.723057] total time : 12332497
  42 [  358.723059] test end
  43 [  359.422038] test init
  44 [  359.426173] test results : time per probe
  45 [  359.426179] number of loops : 20000
  46 [  359.426182] total time : 12332535
  47 [  359.426185] test end
  48
  49 Res : 616.90 cycles per loop.
  50 205.63 ns per loop
  51
  52 Atomic SMP, one trace, flight.
  53
  54
  55 [  111.694180] test init
  56 [  111.700191] test results : time per probe
  57 [  111.700198] number of loops : 20000
  58 [  111.700201] total time : 16925670
  59 [  111.700204] test end
  60 [  112.285716] test init
  61 [  112.291321] test results : time per probe
  62 [  112.291326] number of loops : 20000
  63 [  112.291329] total time : 16766633
  64 [  112.291332] test end
  65 [  112.880602] test init
  66 [  112.884739] test results : time per probe
  67 [  112.884743] number of loops : 20000
  68 [  112.884746] total time : 12358237
  69 [  112.884748] test end
  70
  71 Res : 767.51 cycles per loop
  72 255.83 ns per loop
  73
  74 (205.63-255.83)/255.83 * 100% = 19.62 %
  75
  76
  77 Difference between
  78 cmpxchg 2967855/20000 = 148.39 cycles or 49.46 ns
  79 cmpxchg-up 540577/20000 = 27.02 cycles or 9.00 ns
  80 irq save/restore 12636562/20000 = 631.82 cycles 210.60 ns
  81
  82
  83
  84
  85
  86
  87 Mathieu Desnoyers, November 2006