[x264-devel] Re: x264 & slices

[Tuukka Toivonen]

On Wed, 17 Aug 2005 ollo.diab at gmx.de wrote:

>I tried recent x264 enabled mencoder to trancode a HDTV mpeg2 file to H.264
>avi on a Quad Opteron system running RedHat Enterprise 3 64bit. x264 got
>build with pthread enabled.

Sorry for not answering your first mail, but you really shouldn't
mail directly me about generic x264 questions, but on this list...
(I have nothing to do with the threading support).

>Now if I run mencoder with default x264 encoder settings and add the
>threads=1 parameter, then I get about 5fps, fine. But the odd thing is, all
>4 CPUs are busy at around 25%. Then I tried threads=2, the rate got to 7fps
>and all 4 CPUs are running at 35% load. With threads=3 the rate goes to 8fps
>and with threads=4 goes to 9fps while all CPUs run at 50% load.

Anyway, how can you see how busy each CPU is? My top on Debian
box doesn't display per-CPU busyness, if I remember correctly...

>Somehow I was under the impression the thread parameter more or less defines
>how many CPUs get used. So I expected to see a load of 100% on a single CPU
>with threads=1 and on 2 CPUs with threads=2 and so on.

It defines how many threads to use. Generally OS should schedule
the same thread always on the same CPU, because that's more efficient...
And Linux should do this, maybe your monitoring tool isn't
displaying loads correctly?

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