[haiku-development] Re: [gsoc2012] cpuidle support
- From: Yongcong Du <ycdu.vmcore@xxxxxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Mon, 26 Mar 2012 10:37:52 +0800
I sent this email yesterday. I dunno why the list didn't receive. So send
again today
On Mon, Mar 26, 2012 at 10:15 AM, Yongcong Du <ycdu.vmcore@xxxxxxxxx> wrote:
>
>
> ---------- Forwarded message ----------
> From: Yongcong Du <ycdu.vmcore@xxxxxxxxx>
> Date: Sun, Mar 25, 2012 at 11:53 PM
> Subject: [gsoc2012] cpuidle support
> To: haiku-development@xxxxxxxxxxxxx
>
>
> Dear Haiku development list,
>
> I'm a graduate student from China. I'm interested in embedded software
> development especially lowlevel OS issues, drivers, etc. During my last
> intern job, I implemented Linux cpufreq and cpuidle drivers of one arm SoC
> for one company. IOW my job is focused on the SoC's power efficiency under
> Linux
>
> Per my understanding, Linux power efficiency is improved a lot by the
> following features: cpufreq, tickless and cpuidle. Generally speaking,
> cpufreq is used to change the clock speed of the cpus based on system load
> while cpuidle is used to put cpu into deeper idle stage(for example, C2, C3
> stage on x86) when idle.
>
> I noticed that haiku has supported something similar as cpufreq:
>
> //www.freelists.org/post/haiku-development/Intel-Enhanced-Speedstep-Driver
> and I did find the related drivers in
> src/add-ons/kernel/drivers/power/enhanced_speedstep/
>
> I searched via google and also know haiku has already supported the so
> called "tickless" feature.
>
> I found that cpuidle is missing in haiku. So I'd like to take cpuidle
> framework include some platform's cpuidle driver as my GSoC Haiku project.
> I think this project will benefit haiku in power efficiency and will
> extends my laptop's battery life under haiku(also everyone's laptop users'
> ;)) As for the cpuidle drivers, I may need to handle the complex acpi
> subsystem to get the so called C-State, to put cpu into deep idle etc.. But
> for intel snb, ivb etc.. processors, acpi is not necessary[1] In fact, my
> laptop cpuidle works greatly with the intel_idle driver under linux.
>
> So my plan is to implement cpuidle framework, intel cpu cpuidle driver,
> then acpi cpuidle driver if haiku's acpi support is completed. Here are my
> questions: Is this a project that would be suitable for GSoC? Can we get
> c-state from acpi in haiku?
>
>
> [1] https://lkml.org/lkml/2010/5/28/36
>
> Thanks in advance
>
>
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