[FFmpeg-devel] [PATCH] Fix mm_flags, mm_support for ARM

matthieu castet castet.matthieu
Mon Jun 30 20:29:46 CEST 2008

> Could you or anybody else having compatible ARM device just do some
> benchmarking to confirm my results (I posted benchmarks here multiple 
> times already). It would be a really good help. Because I feel that
> some people here still doubt that it provides a major performance
> improvement.
For dct-test (yes I know it is not a benchmark) on a arm926ejs svn 
implementation got 126.7 kdct/s, your 154.6 kdct/s.

> Once/if the performance improvement is confirmed, a help with integration
> would be really needed. That's not a joke, I really fail to see any problems 
> with the "balign/ASMALIGN/stack alignment" stuff, so I can't fix them. A good
> example of a solution (a working patch) is very much welcome. 
Could you list the integration problem that remains ?
For the alignement stack, may be for old eabi you could use ldm/stm 
instead of double load/store instruction but still use double load/store 
instruction on EABI.

For memory pool, why don't you do only one memory pool ?
With a good packing, this could avoid lot's of balign.

Do you benchmark the improvement by using double load/store instruction. 
My manual (DDI0222B_9EJS_r1p2.pdf) say that for arm9js :
- The LDRD instruction behaves in the same way as an LDM of two registers.
- The STRD instruction behaves in the same way as an STM of two registers.


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