Re: Very bad performance from intel chipset on Thinkpad T540p (2880x1620)

From: Marc MERLIN <marc_xorg@merlins.org>
To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Subject: Re: Very bad performance from intel chipset on Thinkpad T540p (2880x1620)
Date: Fri, 24 Apr 2015 09:18:36 -0700	[thread overview]
Message-ID: <20150424161836.GC30934@merlins.org> (raw)
In-Reply-To: <20150424155353.GJ599@nuc-i3427.alporthouse.com>

On Fri, Apr 24, 2015 at 04:53:53PM +0100, Chris Wilson wrote:
> Whether of not it tears depends upon your window manager. On bare X,
> using mplayer -vo xv or -vo gl, should not tear. Under a compositing
> window manager, it depends upon how it decides to update the screen. To
> force everything to update without tearing, use
> 
> echo > /etc/X11/xorg.conf.d/90-intel.conf <<EOF
> Section "Device"
> 	Identifier "igfx"
> 	Option "TearFree"
> EndSection
> EOF

Cool, thanks for the tip and your help.

I was curious to see how my power use would be, and got about the same power
use at idle with LCD to minimum:
The battery reports a discharge rate of 12.4 W
The estimated remaining time is 7 hours, 27 minutes

Summary: 171.5 wakeups/second,  0.1 GPU ops/seconds, 0.0 VFS ops/sec and 2.0% CPU use

Power est.              Usage       Events/s    Category       Description
  3.73 W      1.9%                      Device         Display backlight
  1.16 W      4.7 ms/s      65.3        Process        [btrfs-transacti]
  741 mW      0.9 ms/s      41.9        Interrupt      [4] block(softirq)
  175 mW    156.0 µs/s       9.9        Process        [rcu_sched]

Then, if I turn my screen off (backlight 0), it actually seems to save another 7W:
The battery reports a discharge rate of 5.06 W
The estimated remaining time is 18 hours, 5 minutes

Summary: 79.4 wakeups/second,  0.2 GPU ops/seconds, 0.0 VFS ops/sec and 1.8% CPU use

Power est.              Usage       Events/s    Category       Description
  229 mW      1.4 ms/s      13.4        Process        [btrfs-transacti]
  181 mW      4.1 ms/s      10.4        Process        /usr/bin/enlightenment
  174 mW    206.2 µs/s      10.2        Interrupt      [4] block(softirq)

So the good news is that the driver sems to do fine on batteries with the
default options now.

Thanks,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/  
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