Michael Hudson-Doyle
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168a51b3a1
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runtime: adjust the arm64 memmove and memclr to operate by word as much as they can
Not only is this an obvious optimization:
benchmark old MB/s new MB/s speedup
BenchmarkMemmove1-4 35.35 29.65 0.84x
BenchmarkMemmove2-4 63.78 52.53 0.82x
BenchmarkMemmove3-4 89.72 73.96 0.82x
BenchmarkMemmove4-4 109.94 95.73 0.87x
BenchmarkMemmove5-4 127.60 112.80 0.88x
BenchmarkMemmove6-4 143.59 126.67 0.88x
BenchmarkMemmove7-4 157.90 138.92 0.88x
BenchmarkMemmove8-4 167.18 231.81 1.39x
BenchmarkMemmove9-4 175.23 252.07 1.44x
BenchmarkMemmove10-4 165.68 261.10 1.58x
BenchmarkMemmove11-4 174.43 263.31 1.51x
BenchmarkMemmove12-4 180.76 267.56 1.48x
BenchmarkMemmove13-4 189.06 284.93 1.51x
BenchmarkMemmove14-4 186.31 284.72 1.53x
BenchmarkMemmove15-4 195.75 281.62 1.44x
BenchmarkMemmove16-4 202.96 439.23 2.16x
BenchmarkMemmove32-4 264.77 775.77 2.93x
BenchmarkMemmove64-4 306.81 1209.64 3.94x
BenchmarkMemmove128-4 357.03 1515.41 4.24x
BenchmarkMemmove256-4 380.77 2066.01 5.43x
BenchmarkMemmove512-4 385.05 2556.45 6.64x
BenchmarkMemmove1024-4 381.23 2804.10 7.36x
BenchmarkMemmove2048-4 379.06 2814.83 7.43x
BenchmarkMemmove4096-4 387.43 3064.96 7.91x
BenchmarkMemmoveUnaligned1-4 28.91 25.40 0.88x
BenchmarkMemmoveUnaligned2-4 56.13 47.56 0.85x
BenchmarkMemmoveUnaligned3-4 74.32 69.31 0.93x
BenchmarkMemmoveUnaligned4-4 97.02 83.58 0.86x
BenchmarkMemmoveUnaligned5-4 110.17 103.62 0.94x
BenchmarkMemmoveUnaligned6-4 124.95 113.26 0.91x
BenchmarkMemmoveUnaligned7-4 142.37 130.82 0.92x
BenchmarkMemmoveUnaligned8-4 151.20 205.64 1.36x
BenchmarkMemmoveUnaligned9-4 166.97 215.42 1.29x
BenchmarkMemmoveUnaligned10-4 148.49 221.22 1.49x
BenchmarkMemmoveUnaligned11-4 159.47 239.57 1.50x
BenchmarkMemmoveUnaligned12-4 163.52 247.32 1.51x
BenchmarkMemmoveUnaligned13-4 167.55 256.54 1.53x
BenchmarkMemmoveUnaligned14-4 175.12 251.03 1.43x
BenchmarkMemmoveUnaligned15-4 192.10 267.13 1.39x
BenchmarkMemmoveUnaligned16-4 190.76 378.87 1.99x
BenchmarkMemmoveUnaligned32-4 259.02 562.98 2.17x
BenchmarkMemmoveUnaligned64-4 317.72 842.44 2.65x
BenchmarkMemmoveUnaligned128-4 355.43 1274.49 3.59x
BenchmarkMemmoveUnaligned256-4 378.17 1815.74 4.80x
BenchmarkMemmoveUnaligned512-4 362.15 2180.81 6.02x
BenchmarkMemmoveUnaligned1024-4 376.07 2453.58 6.52x
BenchmarkMemmoveUnaligned2048-4 381.66 2568.32 6.73x
BenchmarkMemmoveUnaligned4096-4 398.51 2669.36 6.70x
BenchmarkMemclr5-4 113.83 107.93 0.95x
BenchmarkMemclr16-4 223.84 389.63 1.74x
BenchmarkMemclr64-4 421.99 1209.58 2.87x
BenchmarkMemclr256-4 525.94 2411.58 4.59x
BenchmarkMemclr4096-4 581.66 4372.20 7.52x
BenchmarkMemclr65536-4 565.84 4747.48 8.39x
BenchmarkGoMemclr5-4 194.63 160.31 0.82x
BenchmarkGoMemclr16-4 295.30 630.07 2.13x
BenchmarkGoMemclr64-4 480.24 1884.03 3.92x
BenchmarkGoMemclr256-4 540.23 2926.49 5.42x
but it turns out that it's necessary to avoid the GC seeing partially written
pointers.
It's of course possible to be more sophisticated (using ldp/stp to move 16
bytes at a time in the core loop and unrolling the tail copying loops being
the obvious ideas) but I wanted something simple and (reasonably) obviously
correct.
Fixes #12552
Change-Id: Iaeaf8a812cd06f4747ba2f792de1ded738890735
Reviewed-on: https://go-review.googlesource.com/14813
Reviewed-by: Austin Clements <austin@google.com>
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2015-10-08 07:49:35 +00:00 |
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