From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: Does Linux 4.16.1 blast out battery time? (9h+ -> 3h+)
Date: Tue, 24 Apr 2018 10:37:26 +0200
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In-Reply-To: <871sfjtnuy.fsf@gmail.com> (Pierre Neidhardt's message of "Fri,
	13 Apr 2018 15:44:13 +0530")
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To: Pierre Neidhardt <ambrevar@gmail.com>
Cc: help-guix@gnu.org

Hello,

Pierre Neidhardt <ambrevar@gmail.com> skribis:

> With a bit of tweaking, I figured that enabling power management on
> on "Audio codec":
>
> 	echo '1' > '/sys/module/snd_hda_intel/parameters/power_save';
>
> helped a little bit.  But not that much.  Now on 4.14.33, I get 10h,
> while on 4.16.1 I get 5h.
>
> There is something else.

That sounds worrying.  Could you report it upstream?

> By the way, how do I make the above /sys/ tweak permanent on GuixSD?

You could do something like:

  (simple-service 'my-/sys-tweaks activation-service-type
                  #~(call-with-output-file "/sys/=E2=80=A6"
                      (lambda (port)
                        (display "1" port))))

That said, we should probably build a higher-level
=E2=80=98/sys-tweaks-service-type=E2=80=99 where we could directly pass pai=
rs of file
name/values.

Would you like to give it a try?

Thanks,
Ludo=E2=80=99.