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) 0.008 s (x 8 = 0.064 s), bandwidth = 32108.4 MB/s 
Size: 33554432 (262144.00 KiB, 256.00 MiB)
---------------------------------------------------------------------
- # of lanes --- time (s) ---- BandW -- ns/hit -- % Eff -- Speedup --
---------------------------------------------------------------------
           1     4.097515        500     122.1       0%        1.0
           2     2.032233       1008      60.6     101%        2.0
           3     1.369989       1495      40.8      98%        3.0
           4     1.053566       1944      31.4      92%        3.9
           5     0.851974       2404      25.4      96%        4.8
           6     0.713425       2871      21.3      98%        5.7
           7     0.613961       3336      18.3      98%        6.7
           8     0.534792       3830      15.9     103%        7.7
           9     0.476976       4294      14.2      97%        8.6
          10     0.430720       4755      12.8      97%        9.5
          11     0.394397       5193      11.8      93%       10.4
          12     0.363881       5628      10.8      93%       11.3
          13     0.337702       6065      10.1      94%       12.1
          14     0.314476       6512       9.4      96%       13.0
          15     0.294818       6947       8.8      94%       13.9
          16     0.277403       7383       8.3      95%       14.8
          17     0.261545       7830       7.8      97%       15.7
          18     0.247335       8280       7.4      98%       16.6
          19     0.235684       8690       7.0      89%       17.4
          20     0.224952       9104       6.7      91%       18.2
          21     0.219108       9347       6.5      55%       18.7
          22     0.216218       9472       6.4      29%       19.0
          23     0.214867       9531       6.4      14%       19.1
          24     0.214206       9561       6.4       7%       19.1
          25     0.214069       9567       6.4       2%       19.1
          26     0.213797       9579       6.4       3%       19.2
          27     0.214140       9564       6.4      -4%       19.1
          28     0.213697       9584       6.4       6%       19.2
          29     0.213761       9581       6.4      -1%       19.2
          30     0.213678       9585       6.4       1%       19.2
          31     0.213612       9587       6.4       1%       19.2
          32     0.214014       9569       6.4      -6%       19.1
          33     0.214267       9558       6.4      -4%       19.1
          34     0.214262       9558       6.4       0%       19.1
          35     0.213630       9587       6.4      10%       19.2
          36     0.214429       9551       6.4     -13%       19.1
          37     0.213955       9572       6.4       8%       19.2
          38     0.213908       9574       6.4       1%       19.2
          39     0.214153       9563       6.4      -4%       19.1
          40     0.214535       9546       6.4      -7%       19.1
Maybe you have about 22 parallel paths? 
exit=0
