Commit 9ae2ac4d authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

drm: Add TODO item for optimizing format helpers 



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: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarJavier Martinez Canillas <javierm@redhat.com>
Acked-by: default avatarSam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220223193804.18636-6-tzimmermann@suse.de
parent 0d030118

Documentation/gpu/todo.rst

+22 −0
Original line number Diff line number Diff line
@@ -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

-----------------------------------------------------------------