[mythtv-users] System Load/Performance Question

[Brian Wood]

On Feb 20, 2006, at 1:47 PM, Micha Kersloot wrote:

> Hi,
>
> Brian Wood schreef:
>> I know the "can this system do <blank> has been done to death here,
>> but I need some comparisons.
>>
>> The system is an amd64 3700, running Gentoo 2.6.15, MythTV
>> 0.18.1,1.5GB RAM
>
> amd64 3000+, Debian 2.6.15, MythTV 0.18.2, 1GB RAM here
>>
>> We are talking strictly about SDTV here.
>> 2-PVR-150s
> PVR-500 here
>> GeForce-5700 video card w/256MB.
> GeForce-5200 / 128MB
>> nVidia 7676 drivers, no XvMC, MythTV compiled with OpenGL support
> Same.
>
>> Recordings are going onto 2-250GB SATA drives configured Linux kernel
>> software RAID0, JFS filesystem.
>> Ring Buffer is going onto a UDMA 133 250GB single drive, JFS
>> filesystem, no other drive on the IDE channel, The OS is on another
>> partition of this drive.
>
> Recordings and Ringbuffer on 1 250GB SATA drive JFS
>
> With 1 remote frontend watching LiveTV: the load is 0.50, almost no  
> CPU
> usage.
> With 1 local frontend watching LiveTV: the load jumps to 1.5,
> mythfrontend taking 20% and X11 10% CPU usage.
>
> 1 local frontend watching LiveTV + 1 program beeing recorded: the load
> jumps to 3 and LiveTV gets jerky now and then. The recording doesn't
> have any problems. Still only a combined 30% CPU usage.
>
> I do have the feeling the SATA gives some problems. But the strange
> thing is that enabling XvMC brings the load back to acceptable values,
> under 1 in almost all cases. But I really miss the option to user  
> PiP then.
> The drive is connected to a VIA Technologies, Inc. VIA VT6420 SATA  
> RAID
> Controller
> I've found out that 2.6.15 is a bit better than the previous versions.
>
> At the end... You're not alone, i think.
>
>
Perhaps you missed my "SOLVED" post on this thread.

My problem turned out to be PCI latency settings. I have now added a  
transcode job to the mix in addition to a recording and a comm flag  
job and LiveTV is rock solid.

You may have a similar problem, since you seem to be having problems  
with only a 30% CPU load. I'll add something on the subject to the  
Wiki soon, but in the meantime you might want to use lspci -v to  
examine your latencies and setpci to adjust them, see the previous  
post. You've also got the same 6420 SATA controller (VIA calls this a  
RAID bus controller, but it isn't really) as I do, I also set its  
latency to 176 (b0).

I'm still wondering how many "LiveTV breakup" problems might be  
related to this, as I doubt I am the only one to get caught by it,  
but I've not seen it mentioned before.

Thanks again Yan.