diff options
| author | Josselin Costanzi <josselin@costanzi.fr> | 2017-03-19 12:18:08 +0100 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2017-03-21 20:25:17 +0000 |
| commit | 01cd22c68792b659ca0912c104b14c86044110cb (patch) | |
| tree | fc8ebc67f4e8a65b19d7c9f66ac66e265010176b /src/bytes/bytes_generic.go | |
| parent | 0ebaca6ba27534add5930a95acffa9acff182e2b (diff) | |
| download | go-01cd22c68792b659ca0912c104b14c86044110cb.tar.xz | |
bytes: add optimized countByte for amd64
Use SSE/AVX2 when counting a single byte.
Inspired from runtime indexbyte implementation.
Benchmark against previous implementation, where
1 byte in every 8 is the one we are looking for:
* On a machine without AVX2
name old time/op new time/op delta
CountSingle/10-4 61.8ns ±10% 15.6ns ±11% -74.83% (p=0.000 n=10+10)
CountSingle/32-4 100ns ± 4% 17ns ±10% -82.54% (p=0.000 n=10+9)
CountSingle/4K-4 9.66µs ± 3% 0.37µs ± 6% -96.21% (p=0.000 n=10+10)
CountSingle/4M-4 11.0ms ± 6% 0.4ms ± 4% -96.04% (p=0.000 n=10+10)
CountSingle/64M-4 194ms ± 8% 8ms ± 2% -95.64% (p=0.000 n=10+10)
name old speed new speed delta
CountSingle/10-4 162MB/s ±10% 645MB/s ±10% +297.00% (p=0.000 n=10+10)
CountSingle/32-4 321MB/s ± 5% 1844MB/s ± 9% +474.79% (p=0.000 n=10+9)
CountSingle/4K-4 424MB/s ± 3% 11169MB/s ± 6% +2533.10% (p=0.000 n=10+10)
CountSingle/4M-4 381MB/s ± 7% 9609MB/s ± 4% +2421.88% (p=0.000 n=10+10)
CountSingle/64M-4 346MB/s ± 7% 7924MB/s ± 2% +2188.78% (p=0.000 n=10+10)
* On a machine with AVX2
name old time/op new time/op delta
CountSingle/10-8 37.1ns ± 3% 8.2ns ± 1% -77.80% (p=0.000 n=10+10)
CountSingle/32-8 66.1ns ± 3% 9.8ns ± 2% -85.23% (p=0.000 n=10+10)
CountSingle/4K-8 7.36µs ± 3% 0.11µs ± 1% -98.54% (p=0.000 n=10+10)
CountSingle/4M-8 7.46ms ± 2% 0.15ms ± 2% -97.95% (p=0.000 n=10+9)
CountSingle/64M-8 124ms ± 2% 6ms ± 4% -95.09% (p=0.000 n=10+10)
name old speed new speed delta
CountSingle/10-8 269MB/s ± 3% 1213MB/s ± 1% +350.32% (p=0.000 n=10+10)
CountSingle/32-8 484MB/s ± 4% 3277MB/s ± 2% +576.66% (p=0.000 n=10+10)
CountSingle/4K-8 556MB/s ± 3% 37933MB/s ± 1% +6718.36% (p=0.000 n=10+10)
CountSingle/4M-8 562MB/s ± 2% 27444MB/s ± 3% +4783.43% (p=0.000 n=10+9)
CountSingle/64M-8 543MB/s ± 2% 11054MB/s ± 3% +1935.81% (p=0.000 n=10+10)
Fixes #19411
Change-Id: Ieaf20b1fabccabe767c55c66e242e86f3617f883
Reviewed-on: https://go-review.googlesource.com/38258
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Diffstat (limited to 'src/bytes/bytes_generic.go')
| -rw-r--r-- | src/bytes/bytes_generic.go | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/bytes/bytes_generic.go b/src/bytes/bytes_generic.go index 06c9e1f26c..98454bc121 100644 --- a/src/bytes/bytes_generic.go +++ b/src/bytes/bytes_generic.go @@ -39,3 +39,9 @@ func Index(s, sep []byte) int { } return -1 } + +// Count counts the number of non-overlapping instances of sep in s. +// If sep is an empty slice, Count returns 1 + the number of Unicode code points in s. +func Count(s, sep []byte) int { + return countGeneric(s, sep) +} |