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

[Greg Kurz]

On Mon,  3 Aug 2015 23:06:34 +0200
Thomas Huth <thuth at redhat.com> 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!
> 

Wow ! Your two series result in a VERY impressive speedup ! :)

Thanks Thomas !

--
Greg

> 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
>   _FASTMOVE and _FASTRMOVE
>   
> 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
> 
>  include/ppc970/cache.h | 50 +++++++++++++++++++++++++++++++++++++++++++----
>  include/ppcp7/cache.h  | 22 +++++++++++++++++----
>  slof/fs/base.fs        |  2 --
>  slof/fs/fbuffer.fs     | 25 +++++++++++++-----------
>  slof/fs/rmove.fs       | 53 --------------------------------------------------
>  slof/fs/terminal.fs    |  3 ++-
>  slof/prim.code         | 13 +++++++++++++
>  slof/prim.in           |  3 ++-
>  8 files changed, 95 insertions(+), 76 deletions(-)
>  delete mode 100644 slof/fs/rmove.fs
>