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drm: Add TODO item for optimizing format helpers

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Add a TODO item for optimizing blitting and format-conversion helpers
in DRM and fbdev. There's always demand for faster graphics output.

v4:
	* fix typos (Sam)

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/20220223193804.18636-6-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2022-02-23 20:38:04 +01:00
parent 0d03011894
commit 9ae2ac4d31
1 changed files with 22 additions and 0 deletions
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Documentation/gpu/todo.rst
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@ -241,6 +241,28 @@ Contact: Thomas Zimmermann <tzimmermann@suse.de>, Daniel Vetter
Level: Advanced
Benchmark and optimize blitting and format-conversion function
--------------------------------------------------------------
Drawing to dispay memory quickly is crucial for many applications'
performance.
On at least x86-64, sys_imageblit() is significantly slower than
cfb_imageblit(), even though both use the same blitting algorithm and
the latter is written for I/O memory. It turns out that cfb_imageblit()
uses movl instructions, while sys_imageblit apparently does not. This
seems to be a problem with gcc's optimizer. DRM's format-conversion
helpers might be subject to similar issues.
Benchmark and optimize fbdev's sys_() helpers and DRM's format-conversion
helpers. In cases that can be further optimized, maybe implement a different
algorithm. For micro-optimizations, use movl/movq instructions explicitly.
That might possibly require architecture-specific helpers (e.g., storel()
storeq()).
Contact: Thomas Zimmermann <tzimmermann@suse.de>
Level: Intermediate
drm_framebuffer_funcs and drm_mode_config_funcs.fb_create cleanup
-----------------------------------------------------------------