[mythtv-users] RingBuf issues - perhaps

[Mark Garland]

Hi all,

The frontend locked again last night whilst watching a recorded show. 
Really frustrating when the girlfriend looks at me and says 'perhaps we
should have just got a harddisk recorder'!   ;-)
The backend (same box) was recording 3 other things at the same time,
however the HDD didn't seem maxed out at all (and previous iostat results
would suggest this isn't the issue).  The machine was still responsive, just
the frontend was locked.

Frontend logs say:
2009-07-20 21:58:12.991 NVP: Prebuffer wait timed out 10 times.
2009-07-20 21:58:14.592 NVP: Prebuffer wait timed out 10 times.
2009-07-20 21:58:16.193 NVP: Prebuffer wait timed out 10 times.
This normally finishes with a ringbuf error (like below).

Is this a common problem?
I've tried extensive googling, and can find people asking about this but few
solutions.
I've raised the RingBuf setting to 96mb (the max) but this just doesn't feel
right and I'm warned against making it too big because of paging.
What setting do experienced people use?

Any help would be appreciated - even guidance on how to debug this problem.
I'm running 0.21.0+fixes19961-0ubuntu8, on a 5050e, 780g, 1TB HDD, 4gb RAM.

Thanks,

MG
-----
"The most overlooked advantage of owning a computer is that if they foul up
there's no law against whacking them around a bit."
 
-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Mark Garland
Sent: 19 July 2009 12:24
To: mythtv-users at mythtv.org
Subject: [mythtv-users] RingBuf issues - perhaps

Hi all,

I’m newish to mythtv, and very new to this mailing list, so feel free to
suggest basics.
I’ve recently built a combined frontend/backend machine, but have been
having a few issues.
My current problem is that the frontend will randomly lock for 3-5 minutes
mainly when watching live tv (recorded is usually fine) and will then take
me back to the screen showing the list of recordings.

A week ago, it locked at exactly the time when 2 other recordings were due
to start.  I suspected the harddisk was just temporarily very busy for a few
seconds while these recordings started, and that the buffer had run dry.  I
upped the Ring Buffer from 4mb to 50mb to cope with stressful situations and
this improved things.

However, last night, whilst changing channels, it locked.  The frontend logs
show...
2009-07-18 17:20:28.594 NVP: Prebuffer wait timed out 10 times.
2009-07-18 17:20:37.168 NVP: prebuffering pause
2009-07-18 17:20:38.770 NVP: Prebuffer wait timed out 10 times.
... repeated over 100 times, about once a second for the duration of the
lock ...
2009-07-18 17:25:07.775 NVP: Prebuffer wait timed out 10 times.
2009-07-18 17:25:36.518 RingBuf(/content/mythtv/1001_20090718172025.mpg)
Error: Waited 34 seconds for data, aborting.

Then, this morning when watching a program that was being recorded (a few
minutes behind live), it locked.  Frontend logs show...
2009-07-19 09:33:42.349 NVP: prebuffering pause
2009-07-19 09:33:43.196 RingBuf(/content/mythtv/1001_20090719085600.mpg):
Waited 2.0 seconds for data to become available...
2009-07-19 09:33:43.950 NVP: Prebuffer wait timed out 10 times.
2009-07-19 09:33:45.196 RingBuf(/content/mythtv/1001_20090719085600.mpg):
Waited 4.0 seconds for data to become available...
2009-07-19 09:33:45.551 NVP: Prebuffer wait timed out 10 times.
2009-07-19 09:33:47.152 NVP: Prebuffer wait timed out 10 times.
2009-07-19 09:33:48.753 NVP: Prebuffer wait timed out 10 times.
2009-07-19 09:33:49.198 RingBuf(/content/mythtv/1001_20090719085600.mpg):
Waited 8.0 seconds for data to become available...
2009-07-19 09:33:50.354 NVP: Prebuffer wait timed out 10 times.
2009-07-19 09:33:51.955 NVP: Prebuffer wait timed out 10 times.
2009-07-19 09:33:53.556 NVP: Prebuffer wait timed out 10 times.
2009-07-19 09:33:55.157 NVP: Prebuffer wait timed out 10 times.
2009-07-19 09:33:56.758 NVP: Prebuffer wait timed out 10 times.
2009-07-19 09:33:57.201 RingBuf(/content/mythtv/1001_20090719085600.mpg)
Error: Waited 16 seconds for data, aborting.
2009-07-19 09:34:07.833 TV: Attempting to change from WatchingRecording to
None
2009-07-19 09:38:35.193 TV: Changing from WatchingRecording to None
2009-07-19 09:38:35.733 DPMS Reactivated.

Can anyone suggest what I should do?  Should I put the RingBuffer at 100mb?
(there are warnings against making it too big).
Are there other areas that I can look at?  (To rule out the harddisk, I did
run iostat whilst myth was recording 3 programs at once and running
mythcommflag, and it rarely went over 30% usage).
Where else can I look?  Is there any other info I can supply?

Thanks in advance for any help received,

MG
-----
"The most overlooked advantage of owning a computer is that if they foul up
there's no law against whacking them around a bit."
 


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