I was running iperf tests from my raspberry B as client and my NAS as server, both connected with wired gigabit cables and switch. I was getting results about 30 - 40 Mbps (TCP and UDP), which seemed slow to me:
Client connecting to 192.168.222.106, TCP port 5001
TCP window size: 43.8 KByte (default)
[ 3] local 192.168.222.104 port 46480 connected with 192.168.222.106 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.1 sec 50.2 MBytes 41.9 Mbits/sec
. Then I stopped the mediacenter and ran iperf with same options and the results boosted up to 85Mbps which is more what I had expected.
Client connecting to 192.168.222.106, TCP port 5001
TCP window size: 43.8 KByte (default)
[ 3] local 192.168.222.104 port 46506 connected with 192.168.222.106 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 100 MBytes 83.8 Mbits/sec
If I re-start the mediacenter service I go back to those 30 - 40Mbps. I just wanted to confirm if this is normal, and in that case, why is the mediacenter ‘eating’ the bandwith? I also noticed that the Transfer figure is almost half when the mediacenter is running (100MB vs 50.2MB).
Thanks a lot for your help, and for this great software.
Well Kodi needs some CPU power to just “run” and I guess iperf client needs some CPU to process the packages. Suggest you login in parallel ssh session and monitor ssh usage with top
Sorry but I’m not sure if I’m understanding well your suggestion… Do you mean to create two parallel ssh sessions and run iperf simultaneously in both of them? With Kodi stopped?
Yes it is normal for a Pi 1 and no Kodi is not “eating the bandwidth”.
Kodi consumes a significant amount of CPU time on a Pi, and the performance of the USB controller on the Pi (which the Ethernet controller is connected to) is very CPU bound, so anything that consumes CPU time will slow down network throughput.
What you observe is simply the fundamental limitations of CPU speed and USB/Ethernet performance for the Pi.
On a Pi 2, while the underlying bottleneck of the USB/Ethernet controller is still there, the CPU performance is much faster thus more CPU time is left over from Kodi to be used for network processing so you won’t see as much of a fall off in network performance on a Pi 2.
Thank you all for your answers. I checked CPU use and kodi takes around 35% in my Pi. I knew about limitations of Pi 1 but I wasn’t aware they had such impact.
Now both of you have confirmed this is a HW limitation I think it’s time to upgrade… I only need to decide whether to get a new Pi 2 or invest some more on the new Vero 2.
(And sorry for the unfortunate use of the expression ‘eating the bandwith’…)