[MEncoder-users] Fwd: Questions on Mencoder performace
mencoder at lesshaste.plus.com
Tue Jun 6 19:45:13 CEST 2006
larrystotler at netscape.net wrote:
> -----Original Message-----
> From: Corey Hickey <bugfood-ml at fatooh.org>
>> I don't know specifically about your systems, but I wouldn't expect
> much performance out of a P4. I did some rough tests with lavc and
> x264 a while back and found >that a 1.2 GHz Athlon Thunderbird was
> outperforming a 1.7 GHz P4 by 10-20%. As far as I know early Athlon
> processors were roughly equivalent to late P3s, >clock-for-clock, so
> the numbers you posted don't seem out of line.
> Hmmm, I was under the impression that the P4 was actually optimized
> for stuff like this and that it should outperform the Athlon in this
> regard. I've never been a fan of the P4 series, but I ended up with
> with some chips and was hoping that they would be well suited for this
> type of stuff. Oh well. Thanx for the insight.
> I appreciate all the advice that has been given to me by the list
> members. Thanx.
Whenever anybody starts being rude on this list it's because they don't
know the answer. So don't worry about that :)
Your best bet is to experiment. There are too many unknowns and in
particular of course the behaviour of the compiler will make a
considerable difference. One version of gcc with one set of
optimisation flags may accidently squeeze some crucial piece of data
into the L2 cache on a particular processor etc. gcc has never given
any guarantees and I remember compiling code with higher optimisation
levels that ran more slowly and finding that after using -Os it didn't
fit in cache etc.
You may be able to find tools that give you useful stats (e.g.
cachegrind http://valgrind.org/info/tools.html). If you can run
systematic tests using such tools with as many different gccs and
options and cpus as possible then I am sure we would all be very
interested to see the results.
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