Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-12-08 06:10:04 +00:00
Code Issues Projects Releases Packages Wiki Activity

bytes: add optimized countByte for amd64

Browse source 
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>
This commit is contained in:
Josselin Costanzi 2017-03-19 12:18:08 +01:00 • committed by Keith Randall
parent 0ebaca6ba2
commit 01cd22c687
10 changed files with 317 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

1
src/bytes/export_test.go
View file

@ -7,3 +7,4 @@ package bytes
// Export func for testing
var IndexBytePortable = indexBytePortable
var EqualPortable = equalPortable
var CountGeneric = countGeneric