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Date:      Thu, 10 Mar 2016 02:10:37 +0000
From:      Colin Percival <cperciva@tarsnap.com>
To:        Ed Maste <emaste@freebsd.org>, =?UTF-8?Q?Jean-S=c3=a9bastien_P=c3=a9dron?= <dumbbell@freebsd.org>
Cc:        "freebsd-x11@freebsd.org" <freebsd-x11@freebsd.org>
Subject:   Re: i915 update to Linux 3.8 ready!
Message-ID:  <010001535e4a3ff9-1c85dd87-e3cc-4de4-a9a6-5c94a1d2c9ee-000000@email.amazonses.com>
In-Reply-To: <CAPyFy2ATHF0L3DrvMYyRE=tB=igZdzMCBH4JOij%2BnTO84mEXug@mail.gmail.com>
References:  <56D9CE73.7040601@FreeBSD.org> <56DF3F20.8010208@FreeBSD.org> <CAPyFy2ATHF0L3DrvMYyRE=tB=igZdzMCBH4JOij%2BnTO84mEXug@mail.gmail.com>

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On 03/09/16 12:06, Ed Maste wrote:
> On 8 March 2016 at 16:07, Jean-Sébastien Pédron <dumbbell@freebsd.org> wrote:
>> The i915 update is now in HEAD as of r296548:
>> https://lists.freebsd.org/pipermail/svn-src-head/2016-March/083332.html
> 
> This is on a Thinkpad X220 (Sandy Bridge). It has a r286085 kernel
> installed on the disk, and reports 11W while idle at a vt(4) console
> without the driver loaded. After loading i915kms.ko but still at the
> vt(4) console that increased to 14W.
> 
> Booting from a USB stick at r296565 showed 13W initially, rising to
> 25W after loading i915kms.ko. I'll continue to investigate, but would
> like to know what others observe with respect to power consumption on
> other laptops.

On my laptop the new code significantly reduces power consumption.

Laptop is a Dell Latitude E7440 with an Intel Core i5-4300U:
* 7260 wifi replaced with an Atheros card; connected but idle
* powerd is running with default settings
* backlight brightness is at the default setting

Power consumption measured as the median of 15 values from
# while true; do acpiconf -i 0 | grep rate; sleep 10; done

11-CURRENT r296546 (old bits)
OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 3.6, 256 bits)
vt w/o i915kms.ko:	9952 mW
vt w/ i915kms.ko:	9953 mW
KDE idle, screen on:	11664 mW
KDE idle, screen off:	6041 mW

11-CURRENT r296548 (new bits)
OpenGL renderer string: Mesa DRI Intel(R) Haswell Mobile
vt w/o i915kms.ko:	9958 mW
vt w/ i915kms.ko:	9241 mW
KDE idle, screen on:	9377 mW
KDE idle, screen off:	5295 mW

So basically loading the new i915kms.ko saves ~ 0.72 W in a text console;
~ 0.75 W in KDE with the screen off; and ~ 2.29 W in KDE with the screen on.

-- 
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid



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