[FFmpeg-devel] Jpeg2000 decoders comparison

[Reimar Döffinger]

On 06.07.2013, at 00:53, Nicolas BERTRAND <nicoinattendu at gmail.com> wrote:
> May be the pb is more on memory or too much instructions ???

The number of cache misses is a bit of an issue, but it doesn't look all that relevant to me.
However an IPC of 0,7 is just horrible, for some reason some instructions are very slow to execute.
You should probably compare the "perf report" results from running with 4 and with 12 threads and look for any significant changes.
I don't think comparing to libopenjpeg is going to help much, since the question is really what changes with lots of threads.
I thought about it maybe being a cache issue, but these CPUs have massive caches, so it seems quite unlikely, plus behaviour should be vastly better with loweres if the cache were at issue - but in reality it shows about the same behaviour.