linux-kernel - Re: [linux-pm] suspend blockers & Android integration

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Date:	Sun, 6 Jun 2010 14:11:50 +0300
From:	Felipe Contreras <felipe.contreras@...il.com>
To:	david@...g.hm
Cc:	Brian Swetland <swetland@...gle.com>,
	Vitaly Wool <vitalywool@...il.com>,
	Arve Hjønnevåg <arve@...roid.com>,
	Arjan van de Ven <arjan@...radead.org>, tytso@....edu,
	Florian Mickler <florian@...kler.org>,
	Peter Zijlstra <peterz@...radead.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>, Neil Brown <neilb@...e.de>,
	James Bottomley <James.Bottomley@...e.de>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Linux PM <linux-pm@...ts.linux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Felipe Balbi <felipe.balbi@...ia.com>
Subject: Re: [linux-pm] suspend blockers & Android integration

2010/6/6  <david@...g.hm>:
> On Sun, 6 Jun 2010, Brian Swetland wrote:
> if you could shrink the time awake to 0.01 second per wakeup you would shift
> this all up a category (and avoiding the need to wake everything up to
> service a timer would help do this)
>
> this effort very definantly has diminishing returns as you go to larger
> sleep periods as the constant standby power draw becomes more and more
> dominating. someone mentioned that they were getting the sleep time of
> normal systems up past the 1 second mark with the 10 second mark looking
> very attainable. that is where you get the most benifit for whatever changes
> are needed. getting up to a 2 min sleep time really gives you about all the
> benifit that you can get, going from there to 15 min makes very little
> difference.
>
> don't let chasing the best possible sleep time prevent you from considering
> options that would be good enough in time, but would drastically reduce the
> maintinance effort (as things could be upstreamed more easily), and would be
> usable on far more systems.

Not to mention the fact that there's nothing fundamental that prevents
dynamic PM to reach > 15 min idle. It's a matter of time before we
find the tools needed. The amount of work that suspend blockers would
require to implement properly in user-space other than Android just
doesn't match the power savings.

-- 
Felipe Contreras
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