[FFmpeg-devel] Jpeg2000 decoders comparison

[Claudio Freire]

On Thu, Jul 4, 2013 at 7:54 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Thu, Jul 04, 2013 at 10:34:06PM +0200, Nicolas BERTRAND wrote:
>> Hi,
>> I made some perf test to compare jpeg2000 native deocoder with libopenjpeg.
>> I compared the perfs according the number of threads allocated and
>> the number of resolutions levels (lowres)
>>
>>
>> The strange stuff is: in a many core machine( bi xeon, so 12coresx2)
>> , the jpeg2000 decoder is blocled at some fps, and addition of cores
>> no help at all. In reverse with libopenjpeg more we add core, more
>> the decode is fast.
>> In a 4 coresx2 machines. the results are more as expected, and
>> native jpeg2000 decoder is faster in almost all cases.
>>
>> In native jpeg2000 decoder, code looks somewhere blocked or still
>> waiting. But where or how? Right now, no idea why.
>
> A simple way to find out where something is blocked (assuming its
> blocked alot) is to use gdb and hit crtl-c and the look at the
> backtraces of all the threads

Another simple way is to use oprofile[0]

[0] http://oprofile.sourceforge.net/news/