Re: [PATCH documentation 1/2] nohz1: Add documentation.

From: Paul E. McKenney
Date: Fri Apr 12 2013 - 16:39:37 EST


On Fri, Apr 12, 2013 at 10:56:35AM -0700, Arjan van de Ven wrote:
>
> >------------------------------------------------------------------------
> >
> >1. It increases the number of instructions executed on the path
> > to and from the idle loop.
> >
> >2. On many architectures, dyntick-idle mode also increases the
> > number of times that clocks must be reprogrammed, and this
> > reprogramming can be quite expensive.
>
>
> it's really that we're no longer using periodic clocks, but only one-shot clocks only.
> (which then leads to having to program them every time)

Fair enough, but I believe that I have captured this.

> but arguably, that's because of HRTIMERS more than NOHZ
> (e.g. I bet we still turn off periodic even for nohz as long as hrtimers are enabled)

Might be, but the more detail I add, the higher the maintenance burden
keeping this document up to date. ;-)

Thanx, Paul

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