On Sat, Oct 13, 2001 at 11:16:51PM +0200, Michael Zayats wrote: > well back to our cows... hi
> putting DMA might save about 25%...
A very reasonable assumption.
> another 2 questions:
> 1) may be I should just use some optimized version of memcpy? someone knows
> of MMX or SSI uses in glibc? I have very defined hardware to run on...
I tried it (r128's xvshmputimage) before I was told I should try DMA and it
didn't change anything. mmx optimized memcpy helps if you are transferring
inside main memory, but not when the card or bus is the bottleneck. The code I
used is an optimized memcpy taken from mplayer source.
> 2) offtopic: does somebody know how to access shared memory from kernel
> space ( may be I will fix bttv driver to write directly to shared memory,
> this will save me another 25%...)?
Well, unless you somehow tell the bttv driver to use DMA it will still consume
same CPU amounts, but this time not in userspace but inside kernel.
> any help?
Use DMA and tell everyone who claims otherwise that they are wrong and if they
don't believe you, they should ask in lkml :-)
Bye,
Peter Surda (Shurdeek) <[EMAIL PROTECTED]>, ICQ 10236103, +436505122023
--
...and that is how we know the Earth to be banana-shaped.
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