Re: enable i915 rc6 save 7 watt on kernel 3.2

[Chen Wei <weichen027@gmail.com>]

On Thu, Jan 19, 2012 at 10:29:19AM +0100, Martin Steigerwald wrote:
> 
> merkaba:~> cat /etc/modprobe.d/i915-kms.conf 
> options i915 modeset=1 i915_enable_rc6=1 i915_enable_fbc=1 semaphores=1
> 
> There is also
> 
> # The Leading Cause Of The Recent Linux Kernel Power Problems
> # http://www.phoronix.com/scan.php?page=article&item=linux_2638_aspm&num=2
> GRUB_CMDLINE_LINUX_DEFAULT="pcie_aspm=force threadirqs"
> 
> but I didn´t found it to make much of a difference on my ThinkPad T520.
same model here. Power consumption is fluctuate between 14 to 15W. With
pcie_aspm=force, the reading appears lower by less than 1W, it could be
an equipment error. So the difference is small, if any, with the
pcie_aspm tweak. Besides, aspm seems remain disabled: 

wei@Tungsten:~$ dmesg|grep -i aspm
[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-3.2.1
root=UUID=ed888aee-0822-4303-8bea-18f0fbf9ba3a ro quiet pcie_aspm=force
threadirqs
[    0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-3.2.1
root=UUID=ed888aee-0822-4303-8bea-18f0fbf9ba3a ro quiet pcie_aspm=force
threadirqs
[    0.000000] PCIe ASPM is forcibly enabled
[    0.460586] ACPI FADT declares the system doesn't support PCIe ASPM,
so disable it
[    0.582432] ACPI _OSC control for PCIe not granted, disabling ASPM

> 
> Aside from that glxgears is not, was not and likely never will be a 
> meaningful benchmark - it only utilizes a tiny fraction of OpenGL while 
> games and compositing managers use a different and larger set of OpenGL. 
> There are some benchmarks at Phoronix that show increased framerates. One 
> suggested explaination there is that due to the power savings mechanisms 
> like turbo boost for overclocking can be used more often and/or longer.
> 
they are over several hundred MB. Is there any small and simple graphic
test tool like glxgreas?

-- 
Chen Wei