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roystgnr / test-for-iterators

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Workstation timings #1

Open jwpeterson opened 6 years ago

jwpeterson commented 6 years ago

Compiled without any special optimization flags using the Makefile on this branch the results on my Mac workstation using clang 3.9.0 were:

Start = 1530558616,586107
Next = 1530558619,940650
Total time 1 = 3354543
Next = 1530558623,279004
Total time 2 = 3338354
Relative difference 2 = 0
Next = 1530558626,724470
Total time 3 = 3445466
Relative difference 3 = 0.0320853
Next = 1530558630,94975
Total time 4 = 3370505
Relative difference 4 = 0.00963079
Next = 1530558633,466895
Total time 5 = 3371920
Relative difference 5 = 0.0100547
Next = 1530558636,778711
Total time 6 = 3311816
Relative difference 6 = -0.00794943
Next = 1530558640,8491
Total time 7 = 3229780
Relative difference 7 = -0.0325232
Next = 1530558643,374607
Total time 8 = 3366116
Relative difference 8 = 0.00831607
Next = 1530558646,629759
Total time 9 = 3255152
Relative difference 9 = -0.0249231
Next = 1530558649,927448
Total time 10 = 3297689
Relative difference 10 = -0.0121812
Next = 1530558653,161155
Total time 11 = 3233707
Relative difference 11 = -0.0313469
Next = 1530558656,435538
Total time 12 = 3274383
Relative difference 12 = -0.0191624
Next = 1530558660,45830
Total time 13 = 3610292
Relative difference 13 = 0.0814587
Next = 1530558663,333302
Total time 14 = 3287472
Relative difference 14 = -0.0152416
Next = 1530558666,565289
Total time 15 = 3231987
Relative difference 15 = -0.0318621
Next = 1530558669,900213
Total time 16 = 3334924
Relative difference 16 = -0.00102745
Next = 1530558673,185858
Total time 17 = 3285645
Relative difference 17 = -0.0157889

Can you explain how to interpret these results?

jwpeterson commented 6 years ago

Ping @roystgnr

roystgnr commented 6 years ago

Honestly, that looks like noise to me. Case 13 (size_t as the iterator, ptrdiff_t as the data type) is the only clearly more expensive outlier.

Could you try with -O3, though? I wouldn't expect to see anything fancy going on with default optimization.

jwpeterson commented 6 years ago

Timings for same machine with -O3:

Start = 1530643326,141152
Next = 1530643326,497473
Total time 1 = 356321
Next = 1530643326,844194
Total time 2 = 346721
Relative difference 2 = 0
Next = 1530643327,161352
Total time 3 = 317158
Relative difference 3 = -0.0852645
Next = 1530643327,478260
Total time 4 = 316908
Relative difference 4 = -0.0859856
Next = 1530643327,853384
Total time 5 = 375124
Relative difference 5 = 0.0819189
Next = 1530643328,199177
Total time 6 = 345793
Relative difference 6 = -0.0026765
Next = 1530643328,517420
Total time 7 = 318243
Relative difference 7 = -0.0821352
Next = 1530643328,834869
Total time 8 = 317449
Relative difference 8 = -0.0844252
Next = 1530643329,217260
Total time 9 = 382391
Relative difference 9 = 0.102878
Next = 1530643329,564452
Total time 10 = 347192
Relative difference 10 = 0.00135844
Next = 1530643329,882005
Total time 11 = 317553
Relative difference 11 = -0.0841253
Next = 1530643330,201231
Total time 12 = 319226
Relative difference 12 = -0.0793001
Next = 1530643330,577709
Total time 13 = 376478
Relative difference 13 = 0.085824
Next = 1530643330,923969
Total time 14 = 346260
Relative difference 14 = -0.0013296
Next = 1530643331,240905
Total time 15 = 316936
Relative difference 15 = -0.0859048
Next = 1530643331,558230
Total time 16 = 317325
Relative difference 16 = -0.0847829
Next = 1530643331,933776
Total time 17 = 375546
Relative difference 17 = 0.083136