Re: [PATCH] x86: Reduce the default HZ value

[Christoph Lameter]

On Tue, 5 May 2009, Alan Cox wrote:

> HZ on a tickless system has no meaningful relationship to wakup rates -
> which are what I assume you actually care about.

Linux is not tickless. It only switches off ticks if a processor is idle.

> So do you want to change the precision of poll() and other
> functionality ? or do you want to change the wakeup rates and
> corresponding virtualisation overhead ?

select and poll use timeouts based on high resolution timers.

> What measurements have you done that make you think HZ is relevant in a
> tickless kernel ?

Just reading the code gets you there.


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