From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andi Kleen <andi@firstfloor.org>
Subject: Re: suspend blockers & Android integration
Date: Fri, 04 Jun 2010 12:42:26 +0200
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In-Reply-To: <alpine.LFD.2.00.1006032141060.8175@i5.linux-foundation.org> (Linus Torvalds's message of "Thu\, 3 Jun 2010 21\:46\:01 -0700 \(PDT\)")
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To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Arjan van de Ven <arjan@infradead.org>, tytso@mit.edu, Peter Zijlstra <a.p.zijlstra@chello.nl>, Florian Mickler <florian@mickler.org>, Neil Brown <neilb@suse.de>, Brian Swetland <swetland@google.com>, "H. Peter Anvin" <hpa@zytor.com>, LKML <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>, James Bottomley <James.Bottomley@suse.de>, Alan Cox <alan@lxorguk.ukuu.org.uk>, Linux PM <linux-pm@lists.linux-foundation.org>, Ingo Molnar <mingo@elte.hu>, Linux OMAP Mailing List <linux-omap@vger.kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Felipe Balbi <felipe.balbi@nokia.com>

Linus Torvalds <torvalds@linux-foundation.org> writes:

> On Thu, 3 Jun 2010, Arjan van de Ven wrote:
>> 
>> And because there's then no power saving (but a performance cost), it's
>> actually a negative for battery life/total energy.
>
> Including the UP optimizations we do (ie lock prefix removal)? It's 

Those only help the kernel and most workloads do not do enough kernel
execution for it to really matter, but spend most of their
time in user space.

Even if as kernel programmers we often have a different view, in most
cases most cycles are in user space :)

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only.