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mythcommflag kills my box - Epia M10000, Nehemiah C3 1Ghz
http://forum.linhes.org/viewtopic.php?f=11&t=11706		 Page 1 of 2
Author:  abostick [ Mon Sep 18, 2006 9:20 pm ]
Post subject:  mythcommflag kills my box - Epia M10000, Nehemiah C3 1Ghz
Just curious if anyone else has experienced this:

mythcommflag, even when running as a niced process, makes viewing recorded shows unwatchable. Every 1 to 2 seconds, the audio and video on the show I am watching pause for fraction of a second, creating this horrible non stop stuttering effect.

A quick "pkill mythcommflag" from the server prompt immediately removes all of the nasty stutters and the playback resumes silky smooth.

Viewing top with mythcommflag running shows mythcommflag using no more than 50% to 52% of the CPU, all of which are nice cycles, leaving a good 40+% of the cpu free, yet it stutters like all hell.

I run a 7200RPM ATA133 Maxtor drive with 16MB cache. DMA is turned on, so I don't think I am I/O bound, but I have not been to show this one way or another. hdparm shows me:
/dev/hda:
Timing buffered disk reads: 138 MB in 3.04 seconds = 45.42 MB/sec

45MB/s is fast in my book...

Any ideas on this? I basically had to just turn mythcommflag off, with a simple "mv /usr/bin/mythcommflag /usr/bin/mythcommflag.off" until I can resolve it, if it's even possible.

Maybe I just need a faster CPU, I don't know. Anyone else run the C3 Nehemiah and mythcommflag without problems?

Thanks for the help!
Author:  sjerome [ Tue Sep 19, 2006 7:37 am ]
Post subject: 
Another option is to schedule your commflag jobs to run while you sleep, that is what I do. I record FOX HD from 4pm until 8PM, and then have the commflag jobs run from midnight to 3am. Then I watch them the next day.

Also, if you have a slave box, or a different back end box from the frontend, you can have the other box run all of the commflag , and transcode jobs on it, leaving your front end just for watching.

This is what I am planning next, have another desktop in the house run all of the commflag/transcode jobs for me as a slave device.

Hope these ideas help. :P
Author:  thornsoft [ Tue Sep 19, 2006 7:42 am ]
Post subject: 
The "nice" value for mythcommflag is 17. I get stuttering when running commflag unless I renice it to 19. I wish there was a setting for the nice value. Looking at the release notes, they changed from 19 to 17 a few revisions back, and I think it's hard-coded into Myth itself. I am thinking of writing a cron job that looks for it running at 17 and renices to 19. At 19, it's smooth enough to commflag primetime while I'm watching.
Author:  sjerome [ Tue Sep 19, 2006 10:21 am ]
Post subject: 
Forgive me for not being quite literate, but what is the command you run to "re-nice" commflag. This may help me in a situation when I am watching OTA-HDTV, and occasionally I get audio stuttering?
Author:  thornsoft [ Tue Sep 19, 2006 10:28 am ]
Post subject: 
sjerome wrote:
Forgive me for not being quite literate, but what is the command you run to "re-nice" commflag. This may help me in a situation when I am watching OTA-HDTV, and occasionally I get audio stuttering?


I run "top", observe the PID, and then enter: r
then the PID value, then 19
Author:  sjerome [ Tue Sep 19, 2006 10:40 am ]
Post subject: 
:D Hey, thanks. I have been using Linux since kernel 2.14, and I did not know how to do that. Thank goodness for forums. :)
Author:  infinitenothing [ Sat Sep 23, 2006 12:59 am ]
Post subject: 
Yeah, I have a beefy 3200+ AMD and still get exactly this hesitation untill I kill mythcommflag. It takes like 60% of the processor when it runs :lol: Keep me up to speed on the re-nice script.
Author:  seano [ Fri Sep 29, 2006 9:39 pm ]
Post subject: 
Subscribing to thread...

Interested in that re-nice script that I can cron.

Also - how do I schedule the mythcommflag to run during certain hours?
[edit]Turns out the answer to that is right here:
http://mysettopbox.tv/phpBB2/viewtopic.php?t=11842
[/edit]

Thanks!

-seano
Author:  thornsoft [ Sat Sep 30, 2006 5:10 am ]
Post subject: 
re-nice script will get higher priority on my to-do list.
Wifey just woke me up to go and stop the @#$% commercial flagging, so she would watch Numb3rs.....
Author:  infinitenothing [ Sat Sep 30, 2006 11:34 am ]
Post subject: 
seano wrote:
Subscribing to thread...

Interested in that re-nice script that I can cron.

Also - how do I schedule the mythcommflag to run during certain hours?
[edit]Turns out the answer to that is right here:
http://mysettopbox.tv/phpBB2/viewtopic.php?t=11842
[/edit]

Thanks!

-seano

Yeah, that's a good way to do it. It's not ideal though. Ideally, and how I believe it's supposed to work is, mythcommflag would use only otherwise idle CPU cycles so you could flag as soon as possible.
Author:  tjimenez87 [ Sun Oct 01, 2006 11:20 pm ]
Post subject: 
I'm getting this problem too. I just set my commercial flagging to only work from midnight to 6 am. But a script would be nice. I'd set it to a remote button, like the auto-restart frontend scripts.
Author:  wififun [ Mon Oct 30, 2006 11:17 pm ]
Post subject: 
About this topic. In mythtv-setup there is a field for Commercial Flagger command: this is filled in with "mythcommflag" why wouldn't it work to just replace that with "nice -n 19 mythcommflag"?
Author:  thornsoft [ Tue Oct 31, 2006 6:43 am ]
Post subject: 
wififun wrote:
About this topic. In mythtv-setup there is a field for Commercial Flagger command: this is filled in with "mythcommflag" why wouldn't it work to just replace that with "nice -n 19 mythcommflag"?

Try it and let us know!
Author:  khrusher [ Tue Oct 31, 2006 8:17 am ]
Post subject: 
there is also a renice command. no need to use top

Code:
renice
usage: renice priority [ [ -p ] pids ] [ [ -g ] pgrps ] [ [ -u ] users ]
Author:  unkle [ Tue Jan 09, 2007 1:55 pm ]
Post subject: 
Hi,

How much memory have you got ? Does your box swap ?
I havent got a solution to your problem but here is mine to compare:

I've got a via SP8000E which is also Nehemiah/C3 i guess, and 1GB memory.
Im not experiencing problems with stuttering playback during com-flagging. I tried with both nice 17 and 19 and there is no problem.
And this is even though it takes up a LOT of cpu (65-71%)
Code:
9507 mythtv    36  17 95360  48m  12m R 71.5  5.1  11:03.36 mythcommflag


Perhaps the CN400 chipset is utilised during playback (it must be !?!). I dont know which chipset is on your M-board.

However I am experiencing trouble with mplayer stuttering when playing avi-files during com-flagging and this is tedious. (But thats probably better to address in another thread).

TV-Card: PVR-150
KM: R5E50 (fresh install, 2 days old)
Im using SATA which during com-flagging posts:
/dev/sda:
Timing cached reads: 142 MB in 2.03 seconds = 69.78 MB/sec
Timing buffered disk reads: 92 MB in 3.01 seconds = 30.56 MB/sec

And during recording:
/dev/sda:
Timing cached reads: 176 MB in 2.02 seconds = 87.15 MB/sec
Timing buffered disk reads: 104 MB in 3.04 seconds = 34.18 MB/sec

I think this should indicate that your problem is definitely not an io-bottleneck from HD but you're probably already aware of that.

[/code]
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