[MEncoder-users] Fwd: Questions on Mencoder performace

[Matthias Wieser]

Am Dienstag, 6. Juni 2006 18:03 schrieb larrystotler at netscape.net:
> -----Original Message-----
> From: Matthias Wieser <mwieser at gmx.de>
>
> I don't know if 256k is too less for mencoder but generally speaking
> mencoder does not need much cache. An Athlon with 1MByte of cache is
> not
> faster than a 512k version.  It's all about CPU clock, CPU architecture
> and memory bandwidth.
>
> That's the problem.  No one seems to know the answer.

The answer is: It's all about CPU clock, CPU architecture
and memory bandwidth.

> I definately 
> know that moving from 512k to 2048k on my Xeons made no difference.

If I remember correctly even the switch from 256kb to 512kb on older Athlon 
CPUs did not improve the speed of the common video codecs (xvid, divx, WMV, 
lavc,..).
Maybe you will find some benchmarks (Anandtech, tomshardware, ... 
http://www.tomshardware.com/2005/11/21/the_mother_of_all_cpu_charts_2005/
http://www.tomshardware.com/2004/12/21/the_mother_of_all_cpu_charts_part_2/page19.html
http://www.tomshardware.com/2004/12/21/the_mother_of_all_cpu_charts_part_2/page20.html
) where Celerons are compared to other CPUs. It will not be lavc, but divx 
or xvid should behave comparable.

> However, even tho they are full speed L2, they only have a 64bit bus.

On-die L2 is nearly always better than an externel L2 cache. It's not only 
the bandwidth but also the latency.

> The chips with the L2 on the chip have a 256bit bus, which should make
> them faster.  Therefore, a 256k L2 P3 500 should be as fast as a 1MB L2
> Xeon 500 off chip.

As fast? Faster.

> Less cache, but faster access.

Faster cache is much more important!

>
> So, DDR should show more performance than SDRAM?

Yes.