pm2fb with acceleration is slow

pm2fb with acceleration is slow

[Krzysztof Helt]

Hi,

Recently, I have added accelerated methods for fillrect and
copyarea. Scrolling has become very slow (about ten times slower).

The fillrect function speeds ups things - the clear command is
few times faster and scrolling is few percent faster.

The copyarea method makes scrolling much slower. Any hints?

Regards,
Krzysztof

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Re: pm2fb with acceleration is slow

[Antonino A. Daplas]

On Mon, 2007-05-07 at 09:27 +0200, Krzysztof Helt wrote:
> Hi,
> 
> Recently, I have added accelerated methods for fillrect and
> copyarea. Scrolling has become very slow (about ten times slower).
> 
> The fillrect function speeds ups things - the clear command is
> few times faster and scrolling is few percent faster.
> 
> The copyarea method makes scrolling much slower. Any hints?

Without any acceleration, the default scrolling is redraw, basically
it's all framebuffer writes with minimal reads.  With copyarea, reads
generally equal writes.

So one possibility is slow bus reads, even with acceleration. Another
possibility is that wait_pm2() is taking a long time, so you can try
removing that from copyarea.

Another possibility is that you're wait_pm2() function is also waiting
for vblank which can really slow it down.

You can also try to instrument copyarea, ie by making a private ioctl
that calls your copyarea function. Then compare how long it takes to say
copy 1000 500x500 rectangles, with and without the wait_pm2() function.

Tony



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