Re: [PATCH] nohz1: Documentation

From: Rob Landley
Date: Fri Mar 22 2013 - 01:00:02 EST

On 03/21/2013 10:45:07 AM, Arjan van de Ven wrote:
On 3/20/2013 5:27 PM, Steven Rostedt wrote:
I'm not sure I would recommend idle=poll either. It would certainly
work, but it goes to the other extreme. You think NO_HZ=n drains a
battery? Try idle=poll.

do not ever use idle=poll on anything production.. really bad idea.

if you temporary cannot cope with the latency, you can use the PMQOS system
to limit (including going all the way to idle=poll).
but using idle=poll completely is very nasty for the hardware.

In addition we should document that idle=poll will cost you peak performance,
possibly quite a bit.

Where should that be documented?

the same is true for the kernel paramter to some extend; it's there to work around
broken bioses/hardware/etc; if you have a latency/runtime requirement, it's much better
to use PMQOS for this from userspace.

I googled and found

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