[FFmpeg-devel] [RFC] an aes "optimization"

Måns Rullgård mans
Sat Jul 3 02:39:56 CEST 2010


Ramiro Polla <ramiro.polla at gmail.com> writes:

> On Fri, Jul 2, 2010 at 4:15 PM, Guillaume POIRIER <poirierg at gmail.com> wrote:
>> On Fri, Jul 2, 2010 at 9:10 PM, Reimar D?ffinger
>> <Reimar.Doeffinger at gmx.de> wrote:
>> [..]
>>> On PPC64 (using gcc 4.3.5) the timer seems seems to be broken, because
>>> it claims a ridiculously low 213 vs. 216 decicycles (the difference
>>> is below the precision of measurement)...
>>
>> The problem is that on PPC, the only CPU-model independent timer
>> that's available is the "The Time Base Registers", which is increment
>> by one every four *bus* cycles.

Are there CPU-specific counters with better accuracy?  If so, we
should try to support them.

>> CF: ffmpeg-svn/doc/ffmpeg_powerpc_performance_evaluation_howto.txt
>
> That .txt was removed in r23808 along with --powerpc-perf-enable

Apologies if I removed something that's still relevant.  I thought
that entire file was concerned with the broken code I deleted.

-- 
M?ns Rullg?rd
mans at mansr.com



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