[mythtv-users] CONFIG_HZ setting in Linux kernel improved video playback for me

Bob Sully rcs at malibyte.net
Mon Apr 16 05:37:07 UTC 2007


Scott wrote:
>
> On Apr 15, 2007, at 4:31 AM, Bob Sully wrote:
>
>>> I rebuilt my 2.6.20 kernel changing CONFIG_HZ from the default 100Hz
>>> to 300Hz and happily saw butter-smooth video playback for both HDTV
>>> and DVDs.
>>
>> OK, I'm having problems with 2.6.20, so now I'm trying again with
>> Mandriva's 2.6.17-14 multimedia kernel.  If I try to manually
>> change the
>> CONFIG_HZ value in .config to "300" (as I recall someone telling me I
>> could do), it always gets changed back to "1000" on compile.
>>
>> Can this in fact be done, or or are we stuck with the 100, 250 or
>> 1000Hz
>> choices in the older kernels?
>
> The patch for 300 CONFIG_HZ  was a 2.6.20 option. I would use 250 for
> pal and 1000 for NTSC on older kernels. Basically, a higher CONFIG_HZ
> could help with two things:
>
> 1) Prevent lost interrupts on the PCI Bus. On my ASUS P5B board 100HZ
> appeared to be the cause of this
> 2) Smooth the screen redraw and potentially reduce judder?
>
> Word of warning, I could be dead wrong about both things. In my
> specific case, going from 100HZ on a vanilla-sources Gentoo kernel to
> 300HZ helped me much.  I'm pretty sure that I was
>
> With your Mandriva 2.6.17 kernel at 1000HZ I would worry about it.
>
> Read about the 300HZ change in 2.6.20 for yourself at: http://
> kernelnewbies.org/
> Linux_2_6_20#head-3b69e88472d6f53df866b99964c2c1d42316a858
>
> --
> Scott
>

Scott:

Thanks for that, I did check out that link.

I wasn't able to solve the 300Hz issue, but I was able to get things
working pretty well by tweaking the NVidia driver settings and a few other
things - I now have clean HD playback even with the 1000Hz setting. I as I
finally got everything working pretty well with Mandriva 2007 and the
2.6.17-14 multimedia kernel, I'll just wait until they come out with their
2.6.20+ kernel, with all of the third-party modules I need (lirc_imon,
etc.); I compiled some of them myself with only mixed success under Linus'
2.6.20 kernel.

Thanks again - Bob

-- 
________________________________________
Bob Sully - Simi Valley, California, USA
http://www.malibyte.net
http://www.malibyte.com



More information about the mythtv-users mailing list