Date: Fri, 12 Apr 2013 13:39:04 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Arjan van de Ven <arjan@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Borislav Petkov <bp@alien8.de>,
        linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com,
        dipankar@in.ibm.com, akpm@linux-foundation.org,
        mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com,
        tglx@linutronix.de, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu,
        dhowells@redhat.com, edumazet@google.com, darren@dvhart.com,
        fweisbec@gmail.com, sbw@mit.edu, Kevin Hilman <khilman@linaro.org>,
        Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH documentation 1/2] nohz1: Add documentation.
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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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