Commit graph

5 commits

Author SHA1 Message Date
Josh Bleecher Snyder
ca0c449a6b bytes, internal/bytealg: simplify Equal
The compiler has advanced enough that it is cheaper
to convert to strings than to go through the assembly
trampolines to call runtime.memequal.

Simplify Equal accordingly, and cull dead code from bytealg.

While we're here, simplify Equal's documentation.

Fixes #31587

Change-Id: Ie721d33f9a6cbd86b1d873398b20e7882c2c63e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/173323
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-04-24 00:56:36 +00:00
Keith Randall
45964e4f9c internal/bytealg: move Count to bytealg
Move bytes.Count and strings.Count to bytealg.

Update #19792

Change-Id: I3e4e14b504a0b71758885bb131e5656e342cf8cb
Reviewed-on: https://go-review.googlesource.com/98495
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2018-03-04 17:49:25 +00:00
Josselin Costanzi
01cd22c687 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>
2017-03-21 20:25:17 +00:00
Cristian Staretu
90554be030 bytes: export Cap method for buffer
Obtaining the actual size of the underlying storage of the buffer can
be very useful in various scenarios. Long running programs which write
and read large amounts of data to buffers might have to recycle
buffers in order to avoid holding onto potentially huge buffers.

For example, a piece of code which buffers a lot of data in a buffer
might need to release the big buffer and start again with a smaller
buffer after it finished processing the huge amount of data.

In cases where pools of bytes.Buffer are used, being able to check the
size of the allocated data can be very useful.

Instead of forking bytes.Buffer or writing new code, we can export the
Cap() method.

Change-Id: I79d4f0a3cff53b9419d82c8122964761e9e38566
Reviewed-on: https://go-review.googlesource.com/8342
Reviewed-by: Rob Pike <r@golang.org>
2015-04-03 23:50:02 +00:00
Russ Cox
c007ce824d build: move package sources from src/pkg to src
Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.
2014-09-08 00:08:51 -04:00
Renamed from src/pkg/bytes/export_test.go (Browse further)