[mythtv-users] possible alternative to HDhomerun? TBS MOI

[Alan Young]

Russell Gower wrote:
>
>
> Well, I've had my MOI for about a week now, As supplied it's running a buildroot/ulibC userspace and a Kernel without NFS support or loadable module support, So i've rebuilt the kernel and installed Debian Wheezy to a SD card. I have it running a v0.26 slave backend from the debian-multimedia repo. 
>
> I've currently got it recording to a NFS sever but the performance is questionable, it can manage a SD single recording, but seems to struggle with two. on Investigation it would appear to be network related, whilst recording two streams the kernel rpciod process uses around 60%CPU (mythbackend is around 35%) I've done some testing with IPERF and could't get it above 50mbits (where as my master backend to the same server hits 950mbits) so there is something wrong with it's network stack, but I'm not sure where to look.
>
> Any ideas anyone or should I just right this off to experience?
>
> R.
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>   
Some random thoughts that may/may not help...

It appears the MOI might have a single core CPU which may limit its 
ability to split the streaming and network transmission work up.  What 
does the CPU usage show when it's streaming two feeds?

A google search on high cpu usage by rpciod seems to point to nfs 
activity.  The search results pointed to 2.6 kernels.  I think uses 
Wheezy 3.2 kernels.  So that might not be an issue.  Is the master 
backend running the same kernel as the MOI?

Are the nfs mount options the same on the MOI and the master backend?

A ulibC and busybox configuration uses a lot less RAM than a glibc based 
distribution.  It could be that with it using Wheezy it's now running 
out of RAM.  You should be able to recompile their kernel with the extra 
options and use their userspace.  Unfortunately, looking at their 
source, they are using 2.6.35.7.  So it may or may not have the rpciod 
issues seen by the search.  If it does, there are some patches floating 
about that may or may not help.

The other thing I noticed in their source is the "patch" has some 
prebuilt objects for the tuner.   I don't know if those are better/worse 
than the versions that are compiled by the other kernel.

I'm not sure if the 10/100 Ethernet is limiting it too.  From their 
config, it looks like it's using a SMSC911X driver.  If ethtool is 
available, maybe it can change the settings to offload work?  Check to 
see if it running half or full duplex?  Does the interface stats show 
any dropped packets?  Maybe try the usual voodoo of swapping ethernet 
cables and/or ports?

Alan