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| author | Thomas Zimmermann <tzimmermann@suse.de> | 2022-02-23 22:38:03 +0300 |
|---|---|---|
| committer | Thomas Zimmermann <tzimmermann@suse.de> | 2022-03-02 22:22:33 +0300 |
| commit | 0d03011894d23241db1a1cad5c12aede60897d5e (patch) | |
| tree | 5730baad2f6dd3c954e923837ffe731f6135f3ba /Documentation/gpu/todo.rst | |
| parent | 3c54c95bd917d43d12fe1b192df9aa4c5973449b (diff) | |
| download | linux-0d03011894d23241db1a1cad5c12aede60897d5e.tar.xz | |
fbdev: Improve performance of cfb_imageblit()
Improve the performance of cfb_imageblit() by manually unrolling
the inner blitting loop and moving some invariants out. The compiler
failed to do this automatically. This change keeps cfb_imageblit()
in sync with sys_imagebit().
A microbenchmark measures the average number of CPU cycles
for cfb_imageblit() after a stabilizing period of a few minutes
(i7-4790, FullHD, simpledrm, kernel with debugging).
cfb_imageblit(), new: 15724 cycles
cfb_imageblit(): old: 30566 cycles
In the optimized case, cfb_imageblit() is now ~2x faster than before.
v3:
* fix commit description (Pekka)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220223193804.18636-5-tzimmermann@suse.de
Diffstat (limited to 'Documentation/gpu/todo.rst')
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