Strange problem: streaming mkv vs. streaming Blu Ray disc iso / high CPU usage

Dear community,

I’d like to put my Blu Ray collection on the Mycloud EX2.

First, I ripped one of my discs to an ISO image. Then I remuxed the main movie into an mkv file via MakeMKV.

I put the ISO and the mkv on the NAS, and here’s the problem :

  1. If I play the mkv file on my Win 8.1 laptop, the CPU usage of the NAS is 99% the whole time. To be precise: it’s the samba deamon smbd that’s uses the CPU.
  2. However, if I mount the ISO image on my Win 8.1 laptop, and then play the iso, streaming is perfectly fine, and the NAS CPU usage is about 3 to 4% or even 0. That is why this cannot be a network bandwidth issue.

MakeMKV doesn’t encode anything, it simply wraps the Matroska container around the transport streams, so the bitrate of the stream is exactly the same in both cases.

So can someone explain the difference between mkv streaming and ISO streaming in regards to cpu usage of the NAS / Samba server?

Fom my Windows 7 laptop, I played back an mkv file stored on my EX2 and for the whole two minutes that I played the mkv, my cpu did not move above 0-1%. So I can’t seem to reproduce your issue. I did not try with the ISO of a bluray though since you don’t have an issue with that.

1 Like

Thanks for trying!

I have been investigating this further and found out this:

Upon disabling Oplocks for the folder on the NAS where the ISOs and mkvs are stored in, the smbd CPU load issue seems to be gone, i.e. load is around 0-5%, so it looks like Oplocks caused this.

Sadly, I know very little about SMB/Oplocks/Samba in general, so I’m not really sure how Oplocks could be related to this, since it’s supposed to improve performance.

Actually, the share from where the mkv file was played back had oplocks on. I just double-checked and yes, it is on - so I am not convinced that oplocks had anything to do with it.

1 Like

Cybernut1 wrote:

…so I am not convinced that oplocks had anything to do with it.

Yeah, I’m not convinced either. CPU load seems to fluctuate quite a lot with oplocks. Welp…I guess this’ll be as good as a gets for me though.