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
http://elinux.org/images/f/f9/Elc2008_pm_qos_slides.pdf
Rob--
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