[FFmpeg-devel] [PATCH] ffvorbis, better L1 cache use and simplification of code

Benoit Fouet ml_benoitfouet
Wed Oct 1 09:28:42 CEST 2008


Siarhei Siamashka wrote:
> On Tuesday 30 September 2008, Benoit Fouet wrote:
>> Siarhei Siamashka wrote:
>>> Interleaved forward/backward channels processing in order to increase
>>> chances of stepping on already cached data for the cores with extremely
>>> small data cache. Ensure that IMDCT per-rotation does not introduce cache
>>> write misses (write misses on random memory accesses are bad for ARM
>>> cores with no write-allocate cache as they prevent combining data in the
>>> write buffer).
>>> ARM11 with 32K of L1 data cache (no L2) shows performance improvement in
>>> the range 0.5-1% which is not so bad considering that IMDCT/IFFT and also
>>> many other important dsputil functions are not assembly optimized for it
>>> yet.
>>> According to cachegrind simulation, there might be also some improvement
>>> for x86 cores with 16K of L1 data cache (decrease of the number of cache
>>> misses is most visible in this configuration).
>> does this patch depend on another one I missed ?
> It's a single selfcontained patch.

ok, good

>> it doesn't apply as is...
> It doesn't apply to what? Patch was generated against FFmpeg revision 15451,
> but also applies fine to revision 15492 which is current SVN HEAD.

it seems the problem was the end of lines style...

anyway, patch applied

Benoit Fouet
Purple Labs S.A.

More information about the ffmpeg-devel mailing list