Re: userlevel should not need to know about HZ?

Linux Advanced Routing and Traffic Control

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On Thu, Feb 23, 2006 at 05:21:46PM -0300, Andreas Hasenack wrote:
> Kernel people tell me users should never need to know the value of HZ
> used by the currently running kernel. One kernel hacker even told me
> that Linus once changed the value from 100 to 1000 just to see user
> space programs break.

Hmmm. Don't know the context of this statement, but from my (naive) 
point of view, TBF is not a user space program. The user space program 
is tc, and it just sets up structures in the kernel once. The shaping 
itself is done in kernel space.

> So, how do we reliably calculate the minimum value for buffer/burst/maxburts?

Trial & Error, not that I ever had much luck with TBF though...

TBF doesn't really depend on the HZ value - you don't really need to know. 
Still, TBF is affected by the HZ, like many other parts of the kernel too. 
It can't be helped - dunno what else to say about it.

Regards
Andreas Klauer
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