Re: dynamic-hz

[Pavel Machek <pavel@suse.cz>]

Hi!

> > > The performance benefit, if any, is often lost in noise during 
> > >  benchmarks and when there, is less than 1%. So I was wondering if you 
> > >  had some specific advantage in mind for this patch? Is there some 
> > >  arch-specific advantage? I can certainly envision disadvantages to lower Hz.
> > 
> > There are apparently some laptops which exhibit appreciable latency between
> > the start of ACPI sleep and actually consuming less power.  The 1ms wakeup
> > frequency will shorten battery life on these machines significantly.  (I
> > forget the exact numbers - Len will know).
> 
> Is there any recommended lower bound setting?
> Would there be a point in recommending lower settings for desktops
> running only text consoles opposed to X desktops?

I tried defining HZ to 10 once, and there are some #if arrays in the
kernel that prevented me from doing that.

Some drivers do timeouts based on jiffies; having HZ=1 may turn 20msec
timeout into 1sec, that could hurt a lot in the error case...

								Pavel
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