[x265] Question about NUMA and core/thread use

[Michael Lackner]

I found the reason for "why did x265 use 30 threads and not 32, when I have 32 CPUs".

Actually, it was (once again) my own fault. Thinking I know better than x265, I spawned
two lookahead threads starting with 32 logical CPUs ('--lookahead-threads 2').

It seems what x265 does is to reserve two dedicated CPUs for this, but then it couldn't
permanently saturate them.

I still don't know when I should be starting with that stuff for 8K content. 64 CPUs? 256
CPUs? Or should I leave everything to x265? My goal was to be able to fully load as many
CPUs as possible in the future.

In any case, the culprit was myself.

On 05/04/2017 11:18 AM, Mario *LigH* Rohkrämer wrote:
> Am 04.05.2017, 10:58 Uhr, schrieb Michael Lackner <michael.lackner at unileoben.ac.at>:
> 
>> Still wondering why not 32, but ok.
> 
> x265 will calculate how many threads it will really need to utilize the WPP and other
> parallelizable steps, in relation to the frame dimensions and the complexity. It may not
> *need* more than 30 threads, would not have any task to give to two more. Possibly.
> Developers know better...

-- 
Michael Lackner
Lehrstuhl für Informationstechnologie (CiT)
Montanuniversität Leoben
Tel.: +43 (0)3842/402-1505 | Mail: michael.lackner at unileoben.ac.at
Fax.: +43 (0)3842/402-1502 | Web: http://institute.unileoben.ac.at/infotech