[mythtv-users] High mythbackend CPU usage during DVB-T recording (Australia)

HP-mini blm-ubunet at slingshot.co.nz
Mon Jul 15 20:12:48 UTC 2013


On Mon, 2013-07-15 at 14:20 +1000, Christian Hack wrote:
> 
> 
> On 15 July 2013 08:36, Kenni Lund <kenni at kelu.dk> wrote:
>         
>         Den 15/07/2013 00.28 skrev "Kenni Lund" <kenni at kelu.dk>: 
>         
>         >
>         > Also, do you use get your EPG from EIT? If not, you should
>         be able to save some CPU cycles by disabling EIT.
>         >
>         > FYI, the upcoming MythTV 0.27 contains multiple
>         optimizations which should lower the CPU utilization when
>         recording (see for example ticket #12250, #11252 or #11255)
>         Sorry, that should have been #11250, not #12250.
>         
>         Best regards
>         Kenni
>         
> Gave 0.26 a whirl last night and after fighting a number of issues
> which were a pain (mysql timezone issue, mythweb broken,
> mythtv-database upgrade failed, password issue in config.xml), I have
> 0.26 running. Unfortunately that also seems to have mostly broken the
> PiP which had previously worked fairly well in 0.25 with VDPAU :( .
> Just when I needed it for Tour de France and the Ashes...
>  
> Anyway, with 2 HD recordings that I had running CPU usage dropped from
> what would normally be around 130%-140%-150% to around 90%. Still
> fairly high in my opinion but definitely improved noticeably.
>  
> EPG comes from a scraper. EIT is off on all tuners and also even on
> the channels themselves and I've never used it here since it's (well
> was) a bit rubbish.

Old *buntus are likely to cause HDD partition alignment issues (on big
disks) that could cost ~20% disk throughput.

Is the high CPU use caused by one or more CPU cores stuck at 100%?
Are you auto-running mythcommflagging/transcoding?

Are any high CPU usage tasks named mythlogserver? there could be
several..
This seems to go rogue if mythbackend logging options are not right.
Do the BE & mythlogserver logs & their contents appear okay?
This high CPU usage is with no FE playback right ?

Check your mythtv-backend upstart job script against the mythtv wiki
page.
AFAIK mythbuntu has a FE wrapper script that re-spawns the FE if it
crashes.

I don't recall seeing your graphics h/w except for iCPU/IGP.
VDPAU video decode/playback is only possible on nVidia GPU (all recent)
& some (& only some) AMD when using FOSS radeon driver.
VA-API is viable option on some intel GPU & the latest haswell could
eventually be a match for VDPAU.





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