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

[Scott]

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