Re: [9fans] image/memimage speed

[erik quanstrom <quanstro@quanstro.net>]

>> what I'm seeking is a way to avoid the unloadimage() call in nn.c, if
>> that's possible - which, by my understanding of the manual and code,
>> is not.
>> alternatively I could try drawing the memimage to the screen, which I
>> did not find possible directly, only by converting it to an image.
>> any ideas?
>>
>> sorry if I'm missing the obvious.
>>
>
> mostly everything here is now understood by me. sorry for the noise.

i think this is a good point.  reading from the frame buffer can
be deathly slow on a lot of modern video cards.  you're seeing a
factor of 60.  it might be a good idea to keep a copy of the
framebuffer in kernel memory.

i have been using a write-combining framebuffer for about four
months.  (implemented for the x86 architechture via the pat
bits in the page table.)  it has made drawing (writes to the
framebuffer) much faster, but, since reads from the frame buffer
are slow for different reasons, it doesn't help at all for operations
like unhiding windows.

- erik