[hatari-devel] screen conversion performance

[Eero Tamminen]

Hi,

On Friday 03 July 2009, Eero Tamminen wrote:
> Note: My machine is 1.4Ghz AMD Athlon XP with old (obsolete) Matrox G550
> gfx card.  I'm running the display at 16-bits, no compositing.  On this
> system, monochome screen causes <3% CPU usage by Hatari itself and ~10%
> by X server.

I started to wonder these numbers and embarrasingly, I had looked at
the wrong column.  With no frameskip and TOS idling in GEM desktop, Hatari
actually takes in mono mode 33% of CPU and X takes 0.3%.

When Hatari just idles in GEM desktop, the conversion routine takes pretty
insignificant amount of CPU because it just compares the screen pixels to
previous (32-bit screen) to see whether there's anything to update.  CPU
usage goes to (video) interrupt handling, m68k CPU emulation and libasound.
See the attached callmap.

Do you have some use-case (I mean, a program) that does constant full
screen updates in monochrome mode and which could be started from
the auto/-folder for better profiling?


Btw. As to measuring whether somethings faster, Hatari has nowadays
a feature to measure speed, just use --fast-forward.  Whenever you pause
Hatari, it will output to console what FPS (how many VBLs/sec) it achieved
in the meanwhile.   For screen conversion performance evaluation you should
also disable sound and set frameskips to zero:
	--fast-forward yes --frameskips 0 --sound off


	- Eero
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