[x264-devel] Re: x264 & slices

[Juliano Pillati]

ollo.diab at gmx.de wrote:

>Hi Tuukka,
>
>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.
>
>  
>
Your Video format is 720x480 ?

>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.
>
>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.
>
>What is going on? Where is the bottleneck to use multiple CPUs for encoding
>at full load (and thus high fps rate)?
>
>Thanks & regards,   Thomas
>
>  
>

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