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From: "D. Jansen" <d.g.jansen@googlemail.com>
Date: Fri, 27 May 2011 09:22:12 +0200
Message-ID: <BANLkTin4dKQvSa00DsBHUj0z8rOrRXkBfQ@mail.gmail.com>
Subject: Re: [rfc] Ignore Fsync Calls in Laptop_Mode
To: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Oliver Neukum <oneukum@suse.de>, Dave Chinner <david@fromorbit.com>,
        linux-kernel@vger.kernel.org, akpm@linux-foundation.org, tytso@mit.edu
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On Thu, May 26, 2011 at 9:31 PM, Matthew Garrett <mjg59@srcf.ucam.org> wrote:
> On Thu, May 26, 2011 at 09:01:49AM +0200, D. Jansen wrote:
>
>> Exactly. 0.5 Watts is a lot of energy on a modern system. And on some
>> systems with proper link power management in sata and pcie it will be
>> even higher (~1 Watt I think). Think not only of the work that will be
>> lost if the system crashes (unlikely), but also of the work that could
>> never be done because the battery was gone (a certainty).
>
> I don't think link power management is relevant. The hysteresis there is
> sufficiently low that it's only going to make a difference during the
> point where you're actually throwing data across the link.
>
Ok, thanks! I'm not sure how much power could be saved in that case on
different system.
All I know is that it's about 0.5 Watts on my system. All I want is to
help people to be able to take advantage of that extra bit to have
extra battery (in my case 10-20%) for last bit of <insert activity>,
in my case taking notes.
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