number of encode servers on network

[mf627]

question

I am running a 1 gb network on a dedicated smart switch, using a macpro xeon 12 core as master, and a generic linux 8 core xeon at 2.1 ghz encode server. This runs quite well, and achieves near real time conversion without coming close to saturating the network bandwidth. I am thinking of adding in another generic 8 core xeon encode server, and to this end grabbed an older macbook pro quad i7 running at 2.6 ghz using a tb to 1gb ethernet bridge to simulate a second encode server in the system and how it would perform. When I activate the server on the macbook pro limited to 6 threads I invariably get a slowdown in the real time fps being processed overall... with top on the generic 8 core xeon server processor indicating processor utilization dropping by about 600%, while the macbook pro appears to using its allocated 6 threads. If I drop the macbook pro out the system real time fps processing recovers and xeon encode server cpu utilization returns to normal. Not the behavior I expected.

Please note all macs are running same os version, and latest march 2018 dcpomatic software, while generic xeon server also running updated linux system with latest march 2018 dcpomatic software.

Is this normal for a master/slave/slave situation? I don't wish to purchase a second xeon 8 core unless I'm sure I'm going achieve a performance enhancement. Is there a limitation on the efficiency throughput of encode servers?

Thank You

[Carsten]

There have been a few benchmarks submitted which show that you can achieve 40-50fps over a network, however, these tests have been with older versions, and with a higher number of rather slow clients. It also depends a lot on source footage - obviously 4k/16Bit saturates the network much faster than e.g. the BigBuck Bunny benchmark does.

Honestly, I am not sure how a small number of faster CPUs perform together currently, and when you use 4k or 12Bit source footage.

When you experience this slowdown, you may create a log file and send it to Carl, maybe he can find something unusual in them.

From my personal experience, though, this shouldn't happen and you should be fine with a second 8core encoding server.

- Carsten