• Dave Cheney's avatar
    runtime: tune append crossover on amd64 and 386 · 8ce8adbe
    Dave Cheney authored
    Fixes #4963.
    
    Sets the append crossover to 0 on intel platforms.
    
    Results for linux/amd64 Core i5 SNB
    
    benchmark                     old ns/op    new ns/op    delta
    BenchmarkAppend                     102          104   +1.96%
    BenchmarkAppend1Byte                 10           11   +0.92%
    BenchmarkAppend4Bytes                15           11  -28.10%
    BenchmarkAppend7Bytes                17           12  -32.58%
    BenchmarkAppend8Bytes                18           12  -36.17%
    BenchmarkAppend15Bytes               24           11  -55.02%
    BenchmarkAppend16Bytes               25           11  -56.03%
    BenchmarkAppend32Bytes               11           12   +4.31%
    BenchmarkAppendStr1Byte               8            9  +13.99%
    BenchmarkAppendStr4Bytes             11            9  -17.52%
    BenchmarkAppendStr8Bytes             14            9  -35.70%
    BenchmarkAppendStr16Bytes            21            9  -55.19%
    BenchmarkAppendStr32Bytes            10           10   -5.66%
    BenchmarkAppendSpecialCase           49           52   +7.96%
    
    Results for linux/386 Atom(TM) CPU 330 @ 1.60GHz
    
    benchmark                     old ns/op    new ns/op    delta
    BenchmarkAppend                     219          218   -0.46%
    BenchmarkAppend1Byte                 75           72   -3.44%
    BenchmarkAppend4Bytes                92           73  -19.87%
    BenchmarkAppend7Bytes               108           74  -31.20%
    BenchmarkAppend8Bytes               116           74  -35.95%
    BenchmarkAppend15Bytes              162           77  -52.22%
    BenchmarkAppend16Bytes              169           77  -54.20%
    BenchmarkAppend32Bytes               88           86   -2.38%
    BenchmarkAppendStr1Byte              57           59   +3.32%
    BenchmarkAppendStr4Bytes             72           59  -17.40%
    BenchmarkAppendStr8Bytes             92           60  -34.70%
    BenchmarkAppendStr16Bytes           141           63  -54.89%
    BenchmarkAppendStr32Bytes            75           73   -2.64%
    BenchmarkAppendSpecialCase          270          270   +0.00%
    
    R=golang-dev, r
    CC=golang-dev
    https://golang.org/cl/12440044
    8ce8adbe
arch_386.h 260 Bytes