<div class="gmail_quote">On Wed, Jan 20, 2010 at 10:29 PM, <a href="mailto:sonofzev@iinet.net.au">sonofzev@iinet.net.au</a> <span dir="ltr"><<a href="mailto:sonofzev@iinet.net.au">sonofzev@iinet.net.au</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><br>
<br>
On Wed Jan 20 22:20 , Jerry Rubinow sent:<br>
<div class="im"><br>
>Since switching to 0.22, I'd been having frame drops in the recorded files<br>
(problem was definitely in the recording, not the playback), delays in frontend<br>
activity. The frame drops coincided with frontend activity while recording<br>
(playing back files, deleting files). Network showed no errors. CPU usage on<br>
backend remained low (much less than 50%) throughout. Upgrading from weekly<br>
0.22-fixes to trunk had no effect on the issue. <br>
><br>
>Long story short, turning off all logging except for "important" messages caused<br>
all issues to go away. The logging options had been the mythbuntu default<br>
(important,general,record,channel). Turning on more logging options made the<br>
issues worse. Size of log file varied per day between 15MB and 30MB. This<br>
doesn't seem like enough throughput for disk i/o to cause network packets to fall<br>
off the queue. The disk has dma enabled, and the recording storage is on a<br>
different drive than the system drive.<br>
><br>
>Does anyone have any ideas what I might look into to figure out why logging<br>
triggered these problems?<br>
</div>>Myth setup:Revo frontendAthlon 64 3500 backend, with HDHomeRun and HD-PVR tuners<br>
<div class="im">>Mythbuntu 0.22 fixes weekly builds (reverted after trunk didn't help) with<br>
Ubuntu 9.10<br>
>Before upgrading to 0.22, I was running 0.21-fixes on an older computer (Asus<br>
A7N8X-X) no issues. I upgrade to 0.22-fixes and added the HD-PVR, and started<br>
having problems. Switched the BE onto the Athlon 64 box, problems didn't change.<br>
Problems occurred whether or not I was using the HD-PVR. I believe (but I can't<br>
swear) I had the same logging options turned on when I was running 0.21.<br>
><br>
>Thanks for any ideas.<br>
>-Jerry<br>
<br>
</div>Not sure about your particular scenario.. But logging increases disk-write<br>
activity ... Working in call-delivery systems (call centre applications) we<br>
generally recommend to our customers they have logging kept to a minimum unless<br>
we are looking for the cause of a fault...<br>
<br>
If you have logging turned on, it's best that it isn't on the same disk as your<br>
Myth Database..<br></blockquote><div><br></div><div>Is myth's mysql activity that intense? hdparm reports that the system/mysql/logging drive does timed cache reads at 862 MB/sec, and buffered disk reads at 64 MB/sec. dd can write 58MB/sec. I would have thought lots of small writes from the logging would be buffered and wouldn't be enough to overwhelm the disk io.</div>
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