[SLOF] [PATCH v3 0/6] Accelerate the screen drawing functions

Alexey Kardashevskiy aik at ozlabs.ru
Wed Aug 5 16:23:12 AEST 2015

On 08/04/2015 07:06 AM, Thomas Huth wrote:
> While working on the cursor drawing issues, I've noticed that
> some other functions in the framebuffer code of SLOF could be
> accelerated quite a bit. The first two patches are rather
> cosmetic and do not contribute much to the speed improvement,
> but the following two patches speed up the drawing quite a lot!
> There are two core functions, MRMOVE and RFILL, which are used
> by the drawing functions to write to the framebuffer and which
> were not really adapted to the KVMPPC_H_LOGICAL_MEMOP of
> board-qemu yet (i.e. they were written with js2x in mind).
> So they both triggered a hypercall for every 8-byte access
> to the framebuffer instead of handling larger transfers at
> once. By implementing a proper accelerated version of these
> calls, the text drawing and screen-erasing can be speed-up
> quite a bit:
> - Fixing MRMOVE improves the character drawing by factor 2
>    or more (the "benchmark" that I've published in my
>    cover-letter of the cursor-improvement series earlier
>    this week now only takes 0.3 s instead of 0.8 s!)
> - Fixing RFILL improves the screen erasing function by
>    factor 10 or even more! The function "erase-screen"
>    took approx. 1.3 s before the fix, and now only takes
>    0.1 s after the fix.
> Both fixes also speed up grub in graphical mode quite a bit,
> since grub apparently uses the firmware to erase the screen.
> v3:
> - Fixed stupid bug in RFILL for js2x (loop counter was not
>    properly decremented)
> v2:
> - Cosmetic changes according to the review feedback from v1
> - Move the hunk to remove the RMOVE64 comment into a
>    separate patch
> - Added a new patch to fix the 16-bit alignment check in
> Thomas Huth (6):
>    terminal: Disable the terminal-write trace by default
>    fbuffer: Precalculate line length in bytes
>    fbuffer: Implement MRMOVE as an accelerated primitive
>    fbuffer: Implement RFILL as an accelerated primitive
>    Remove unused RMOVE64 stub
>    Add missing half word access case to _FASTRMOVE and _FASTMOVE

Thanks, applied. btw 4/6 required "make distclean", worth mentioning.


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