[mythtv-users] Mythpreviewgen

Josu Lazkano josu.lazkano at gmail.com
Wed Sep 21 13:24:07 UTC 2011

2011/9/20 Josu Lazkano <josu.lazkano at gmail.com>:
> 2011/9/20 Josu Lazkano <josu.lazkano at gmail.com>:
>> 2011/9/20 Michael T. Dean <mtdean at thirdcontact.com>:
>>> On 09/19/2011 04:56 PM, Josu Lazkano wrote:
>>>> Hello to all, I write lots of post this last few days, I am trying to
>>>> get a stable system, I am getting lots of playback pauses from time. I
>>>> have two Nvidia ION boards with same problems, I started all these
>>>> post trying to fix my problem:
>>>> http://www.gossamer-threads.com/lists/engine?list=mythtv;do=search_results;search_forum=forum_1;search_string=josu%20lazkano;search_type=AND&sb=post_time
>>>> I am watching LiveTV with a "htop" terminal and I just hunt a process
>>>> with high CPU on the playback stops, is the /usr/bin/mythpreviewgen.
>>>> It is correlated with the stops, it happens 3 more time.
>>>> I got a screenshot: http://dl.dropbox.com/u/1541853/mythpreviewgen.png
>>>> There are 2 mythpreviewgen process with 27% and 17% CPU usage. Could
>>>> it be this the cause of my playback stops? I read the wiki page about
>>>> the Mythpreviewgen (http://www.mythtv.org/wiki/Mythpreviewgen), but
>>>> there is no much info about it.
>>>> Could I limit the CPU usage for this process? I would appreciate any
>>>> help, I hope this will fix all my problems.
>>>> Thanks for all help, best regards.
>>> mythpreviewgen (and possibly some other "start/end of recordings"
>>> activities) are definitely the cause of the "short playback pauses at
>>> program transition".  It's possible mythpreviewgen could cause similar
>>> pauses at other times if something kicks it off (like someone
>>> setting/clearing a bookmark on a recording on another frontend while
>>> you're watching a recording on yours).
>>> Doesn't look like there's any code in mythpreviewgen to set a nice
>>> value.  You could stick a myth_nice(17); somewhere in there and see if
>>> it helps.
>>> Mike
>>> _______________________________________________
>>> mythtv-users mailing list
>>> mythtv-users at mythtv.org
>>> http://www.mythtv.org/mailman/listinfo/mythtv-users
>> Thanks Mike, sorry but I don't know where to add the "myth_nice(17);".
>> Is possible to disable this function? I never try it, but there is a
>> cpulimit software to limit the CPU usage of a process, could be a good
>> option?
>> Thanks and best regards.
>> I want to try
>> --
>> Josu Lazkano
> Hello again, I am reading about nice() and ionice(). It looks like
> they are for scheduled the CPU utilization, but I have no idea where
> to configure it.
> I read that -20 is the highest priority and 20 is the lowest priority,
> so it will be good idea to assign 17 to mythpreviewgen as Mike
> recomend.
> Please, can you help for this configuration? Where I must configure it?
> Thanks for all your help.
> Regards.
> --
> Josu Lazkano

Hello again, I notice that mythpreviewgen is executed on program
change and on channel change in LiveTV, it taken more than 50% of CPU
usage and it generate lots of playback stops.

I read about the nice(), but it must be executed as root thi way: nice
-n 17 /usr/bin/mythpreviewgen

But I don't know where to put this code. Need I to change the source
code and compile it? I never compile MythTT, I just use the
debian-multimedia repository. I think this will be the cause of all my
playback problems, I will appreciate any help.

Thanks and best regards.

Josu Lazkano

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