[Libva] Is there a limit on number of parallel encoders?

[Xiang, Haihao]

On Wed, 2014-05-28 at 12:34 +0200, Torbjorn tyridal wrote: 
> I have the following case on a haswell 4770R  (gigabyte brix)
> 
> A libva based encoder reads raw 1920x1088 nv12 frames from file on
> ramfs. Encoding set to 10 slices, fixed qp (26). cpu governor set to
> performance.

> if I run two of the above in parallel, each goes along at 230fps, 18%
> cpu (top). ie a total of 460 fps/36% cpu
> If I then add a third instance the frame rate drops to 72fps (total 216)
> and the cpu load jumps to 86 / 198%.
> 
> Is there an explanation for the above in libva? 

I tested a 1920x1080 YUV file with cases avcenc on my HSW:

1 * 206 fps, 2 * 149 fps, 3 * 99 fs, 4 * 74 fps.

What is the result if you set to 1 slice per frame ?

Thanks
Haihao

> Decoder scales nicely: 1 * 926 fps, 2 * 626 fps, 3 * 411 fps, 4 * 288
> fps, 5 * 229 fps ...

> 
> Cheers, T.
> 
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