Created
June 28, 2012 17:24
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Branch prediction is detectable on jruby
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require 'benchmark' | |
array_size = 32768 | |
data = Array.new(array_size) | |
array_size.times { |c| data[c] = rand(256)} | |
data_sorted = data.sort | |
def sum(array) | |
sum = 0; | |
for i in 1..1000 # calm down, MRI is slooowwww | |
for j in 0..(array.size - 1) | |
sum += array[j] if array[j] >= 128 | |
end | |
end | |
puts "Total: #{sum}" | |
end | |
puts 'Unsorted' | |
5.times { puts Benchmark.measure { sum(data) } } | |
puts 'Sorted' | |
5.times { puts Benchmark.measure { sum(data_sorted) } } |
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$ /usr/bin/ruby branch_predict.rb | |
Unsorted | |
Total: 3159277000 | |
15.750000 0.020000 15.770000 ( 16.237136) | |
Total: 3159277000 | |
15.900000 0.030000 15.930000 ( 16.129206) | |
Total: 3159277000 | |
15.830000 0.010000 15.840000 ( 16.007797) | |
Total: 3159277000 | |
15.810000 0.030000 15.840000 ( 16.122798) | |
Total: 3159277000 | |
15.830000 0.020000 15.850000 ( 16.215970) | |
Sorted | |
Total: 3159277000 | |
15.810000 0.030000 15.840000 ( 16.722894) | |
Total: 3159277000 | |
15.790000 0.010000 15.800000 ( 15.894834) | |
Total: 3159277000 | |
15.750000 0.010000 15.760000 ( 15.970007) | |
Total: 3159277000 | |
15.800000 0.020000 15.820000 ( 16.326240) | |
Total: 3159277000 | |
15.660000 0.020000 15.680000 ( 15.868698) | |
$ jruby branch_predict.rb | |
Unsorted | |
Total: 3154163000 | |
2.920000 0.130000 3.050000 ( 2.761000) | |
Total: 3154163000 | |
2.280000 0.010000 2.290000 ( 2.295000) | |
Total: 3154163000 | |
2.290000 0.020000 2.310000 ( 2.316000) | |
Total: 3154163000 | |
2.280000 0.010000 2.290000 ( 2.309000) | |
Total: 3154163000 | |
2.310000 0.010000 2.320000 ( 2.357000) | |
Sorted | |
Total: 3154163000 | |
2.150000 0.030000 2.180000 ( 2.239000) | |
Total: 3154163000 | |
2.130000 0.000000 2.130000 ( 2.146000) | |
Total: 3154163000 | |
2.110000 0.010000 2.120000 ( 2.120000) | |
Total: 3154163000 | |
2.120000 0.010000 2.130000 ( 2.122000) | |
Total: 3154163000 | |
2.140000 0.010000 2.150000 ( 2.116000) |
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