[mythtv-users] Fixed: Choppy watching current recording.

R. G. Newbury newbury at mandamus.org
Fri Jan 26 14:27:29 UTC 2007

Billy Macdonald wrote:
> Hi,
>     I just setup two HD Homerun devices and was having problems
> watchingrecording in progress.  I was getting prebuffering pauses and
> top was showing 15-25% iowait.
>    I could record four HD shows at once and watch a fifth prerecorded
> HD show and that was fine, it was only watching a recording in
> progress that was bad.  I changed the NFS mount options from a rsize &
> wsize of 32768 to a rsize & wsize of 8192.  This lowered the iowait
> times to around 4%.  Playback of a recording in progress now works.
>    I'm not quite sure why this made the difference as I have the
> network bandwidth since watching a HD recording while four others are
> being recorded shows an iowait of 0% and no problems at all.
> Myth-0.20-fixes.  Maybe the it was the file access in 32k chunks that
> was the problem?

> I couldn't find much info troubleshooting this but after the fix I
> noticed that 8192 is the suggested value in the setup docs, so I guess
> it's there for a reason.

I was having some firewall problems with NFS mounts and found the Linux 
NFS Howto (just google that phrase).

Section 5 discusses how to find the optimum rsize and wsize values and 
gives one-line commands which allow you to test various sizes.

I found that 4096 was the fastest size for my setup (possibly because 
the laptop is a wireless connection.

And there should be a reference in the wiki, so I'm off to there now.


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