Initializing array made of 33554432 64-bit words (256.00 MiB).
Source pages allocated with transparent hugepages: 100.0% (65536 pages, 100.0% flagged)
Legend:
  BandW: Implied bandwidth (assuming 64-byte cache line) in MB/s
  % Eff: Effectiness of this lane count compared to the prior, as a % of ideal
  Speedup: Speedup factor for this many lanes versus one lane
Applying Sattolo's algorithm... chain total: 33554432
Time to sum up the array (linear scan) 0.007 s (x 8 = 0.059 s), bandwidth = 34688.3 MB/s 
Size: 33554432 (262144.00 KiB, 256.00 MiB)
---------------------------------------------------------------------
- # of lanes --- time (s) ---- BandW -- ns/hit -- % Eff -- Speedup --
---------------------------------------------------------------------
           1     3.788269        541     112.9       0%        1.0
           2     1.894492       1081      56.5     100%        2.0
           3     1.258702       1627      37.5     101%        3.0
           4     0.942248       2174      28.1     101%        4.0
           5     0.752902       2720      22.4     100%        5.0
           6     0.627340       3265      18.7     100%        6.0
           7     0.537986       3807      16.0     100%        7.0
           8     0.470725       4351      14.0     100%        8.0
           9     0.419241       4885      12.5      98%        9.0
          10     0.377224       5429      11.2     100%       10.0
          11     0.343156       5968      10.2      99%       11.0
          12     0.314295       6516       9.4     101%       12.1
          13     0.290188       7058       8.6     100%       13.1
          14     0.275319       7439       8.2      72%       13.8
          15     0.254070       8061       7.6     116%       14.9
          16     0.238534       8586       7.1      98%       15.9
          17     0.226097       9058       6.7      89%       16.8
          18     0.217432       9419       6.5      69%       17.4
          19     0.214605       9543       6.4      25%       17.7
          20     0.212579       9634       6.3      19%       17.8
          21     0.211455       9685       6.3      11%       17.9
          22     0.211031       9705       6.3       4%       18.0
          23     0.210812       9715       6.3       2%       18.0
          24     0.210905       9711       6.3      -1%       18.0
          25     0.210695       9720       6.3       2%       18.0
          26     0.209749       9764       6.3      12%       18.1
          27     0.209934       9755       6.3      -2%       18.0
          28     0.210759       9717       6.3     -11%       18.0
          29     0.210408       9733       6.3       5%       18.0
          30     0.211153       9699       6.3     -11%       17.9
          31     0.212303       9647       6.3     -17%       17.8
          32     0.212780       9625       6.3      -7%       17.8
          33     0.210634       9723       6.3      33%       18.0
          34     0.211355       9690       6.3     -12%       17.9
          35     0.210293       9739       6.3      18%       18.0
          36     0.211882       9666       6.3     -27%       17.9
          37     0.211618       9678       6.3       5%       17.9
          38     0.211513       9683       6.3       2%       17.9
          39     0.209593       9771       6.2      35%       18.1
          40     0.211394       9688       6.3     -34%       17.9
Maybe you have about 19 parallel paths? 
exit=0
