Re: [RFC PATCH] Turn off the tick even when not idle

[Pavel Machek]

Hi!

> When a process does some number crunching for a while, without involving
> the kernel, the kernel still interrupts it HZ times per second to figure
> out if it has any work to do.  With a system dedicated to doing such
> number crunching, the answer will almost always come up "no"; however,
> the kernel takes a while figuring out all the "no"s from various
> subsystems, every timer tick.  On my system, the timer tick takes about
> 80us, every 1/HZ seconds; that represents a significant overhead.  80us
> out of every 1ms, for instance, means 8% overhead.  Furthermore, the
> time taken varies, and the timer interrupts lead to jitter in the
> performance of the number crunching.

8% overhead on hz=1000 is quite high --- what hw is that?

You should be able to get similar results with HZ=1, right?
									Pavel

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