tree 0a9c7cbdfa3fe5f8f30a0c0fde3359a7c384fc01
parent 4b9b9714365c0180008ba5bcfc971a6becb806c9
author Nigel Tao <nigeltao@golang.org> 1590982308 +1000
committer Nigel Tao <nigeltao@golang.org> 1590983990 +1000

Drop unnecessary memcpy in do_bench_image_decode

This doesn't affect the std/bmp or std/gif implementations per se, only
the code that benches them. Prior to this commit, the source file was
first decoded into a pixel buffer and then always copied from the
(2-dimensional) wuffs_base__pixel_buffer to a (1-dimensional)
wuffs_base_io_buffer. That copy is useful for *tests*, which compare
that io_buffer's contents to a known good result (i.e. a separate I/O
buffer filled with the contents of a golden file), but it isn't
necessary for *benches*. Dropping that unnecessary copy reduces the
total time per iteration, and therefore increases the reported speed.

name                                        old speed      new speed       delta

wuffs_bmp_decode_40k/clang5                 2.09GB/s ± 2%   2.48GB/s ± 0%  +18.78%  (p=0.008 n=5+5)

wuffs_bmp_decode_40k/gcc7                   1.73GB/s ± 1%   1.93GB/s ± 0%  +11.54%  (p=0.008 n=5+5)

wuffs_gif_decode_1k_bw/clang5                291MB/s ± 0%    376MB/s ± 1%  +29.14%  (p=0.008 n=5+5)
wuffs_gif_decode_1k_color_full_init/clang5  95.3MB/s ± 1%  103.2MB/s ± 1%   +8.37%  (p=0.008 n=5+5)
wuffs_gif_decode_1k_color_part_init/clang5   117MB/s ± 0%    130MB/s ± 0%  +10.68%  (p=0.008 n=5+5)
wuffs_gif_decode_10k_bgra/clang5             469MB/s ± 0%    489MB/s ± 1%   +4.39%  (p=0.008 n=5+5)
wuffs_gif_decode_10k_indexed/clang5          126MB/s ± 1%    130MB/s ± 1%   +3.50%  (p=0.008 n=5+5)
wuffs_gif_decode_20k/clang5                  152MB/s ± 0%    156MB/s ± 1%   +2.77%  (p=0.008 n=5+5)
wuffs_gif_decode_100k_artificial/clang5      318MB/s ± 0%    329MB/s ± 0%   +3.53%  (p=0.008 n=5+5)
wuffs_gif_decode_100k_realistic/clang5       137MB/s ± 0%    139MB/s ± 0%   +1.40%  (p=0.008 n=5+5)
wuffs_gif_decode_1000k_full_init/clang5      138MB/s ± 0%    140MB/s ± 1%   +1.45%  (p=0.008 n=5+5)
wuffs_gif_decode_1000k_part_init/clang5      139MB/s ± 0%    140MB/s ± 1%   +1.03%  (p=0.008 n=5+5)
wuffs_gif_decode_anim_screencap/clang5       661MB/s ± 0%    747MB/s ± 1%  +13.08%  (p=0.008 n=5+5)

mimic_gif_decode_1k_bw/clang5               92.0MB/s ± 0%   91.9MB/s ± 1%     ~     (p=0.841 n=5+5)
mimic_gif_decode_1k_color/clang5            45.5MB/s ± 0%   45.7MB/s ± 0%   +0.45%  (p=0.032 n=5+4)
mimic_gif_decode_10k_indexed/clang5         53.5MB/s ± 0%   53.7MB/s ± 0%   +0.31%  (p=0.032 n=5+4)
mimic_gif_decode_20k/clang5                 55.5MB/s ± 0%   55.1MB/s ± 2%     ~     (p=0.690 n=5+5)
mimic_gif_decode_100k_artificial/clang5     88.8MB/s ± 0%   89.0MB/s ± 1%     ~     (p=0.151 n=5+5)
mimic_gif_decode_100k_realistic/clang5      53.5MB/s ± 1%   53.7MB/s ± 0%   +0.31%  (p=0.024 n=5+5)
mimic_gif_decode_1000k/clang5               54.6MB/s ± 0%   54.6MB/s ± 1%     ~     (p=0.222 n=5+5)
mimic_gif_decode_anim_screencap/clang5       106MB/s ± 0%    109MB/s ± 0%   +2.59%  (p=0.008 n=5+5)

wuffs_gif_decode_1k_bw/gcc7                  284MB/s ± 0%    356MB/s ± 0%  +25.33%  (p=0.016 n=4+5)
wuffs_gif_decode_1k_color_full_init/gcc7    82.1MB/s ± 0%   95.3MB/s ± 0%  +16.08%  (p=0.008 n=5+5)
wuffs_gif_decode_1k_color_part_init/gcc7    97.5MB/s ± 0%  117.4MB/s ± 0%  +20.39%  (p=0.008 n=5+5)
wuffs_gif_decode_10k_bgra/gcc7               345MB/s ± 0%    396MB/s ± 0%  +14.71%  (p=0.016 n=4+5)
wuffs_gif_decode_10k_indexed/gcc7            104MB/s ± 0%    121MB/s ± 0%  +16.38%  (p=0.008 n=5+5)
wuffs_gif_decode_20k/gcc7                    131MB/s ± 0%    149MB/s ± 0%  +13.55%  (p=0.008 n=5+5)
wuffs_gif_decode_100k_artificial/gcc7        293MB/s ± 0%    321MB/s ± 1%   +9.77%  (p=0.008 n=5+5)
wuffs_gif_decode_100k_realistic/gcc7         116MB/s ± 1%    130MB/s ± 1%  +12.10%  (p=0.008 n=5+5)
wuffs_gif_decode_1000k_full_init/gcc7        117MB/s ± 1%    132MB/s ± 1%  +12.53%  (p=0.008 n=5+5)
wuffs_gif_decode_1000k_part_init/gcc7        117MB/s ± 0%    132MB/s ± 1%  +12.20%  (p=0.008 n=5+5)
wuffs_gif_decode_anim_screencap/gcc7         615MB/s ± 2%    711MB/s ± 2%  +15.53%  (p=0.008 n=5+5)

mimic_gif_decode_1k_bw/gcc7                 91.4MB/s ± 0%   91.7MB/s ± 1%     ~     (p=0.095 n=5+5)
mimic_gif_decode_1k_color/gcc7              46.3MB/s ± 0%   46.2MB/s ± 2%     ~     (p=0.841 n=5+5)
mimic_gif_decode_10k_indexed/gcc7           51.9MB/s ± 1%   51.7MB/s ± 1%     ~     (p=0.310 n=5+5)
mimic_gif_decode_20k/gcc7                   54.2MB/s ± 0%   54.2MB/s ± 1%     ~     (p=0.421 n=5+5)
mimic_gif_decode_100k_artificial/gcc7       88.4MB/s ± 1%   88.7MB/s ± 1%     ~     (p=0.222 n=5+5)
mimic_gif_decode_100k_realistic/gcc7        53.7MB/s ± 0%   53.7MB/s ± 0%     ~     (p=0.206 n=5+5)
mimic_gif_decode_1000k/gcc7                 53.8MB/s ± 2%   54.0MB/s ± 2%     ~     (p=0.690 n=5+5)
mimic_gif_decode_anim_screencap/gcc7         106MB/s ± 0%    109MB/s ± 0%   +2.79%  (p=0.008 n=5+5)