On 29 December 2012 01:11, Todd Poynor <toddpoy...@google.com> wrote:
> Thanks Viresh, I'm out of the office right now but will look at this more
> closely early next year.

Happy New Year!!

> There's discussions starting among various folks about how to handle
> big.LITTLE and what role cpufreq governors vs. platform code play a part in
> that, so all this will probably be something a little longer-term as it
> shakes out.  I've also recently added a target_loads attribute that can pair
> CPU frequencies with target loads (at speed 200M try for target load 85%, at
> speed 1.5G try for load 98%...), which may also need adjustment if the
> governors manage the little CPUs.  If the little CPUs have CPU numbers
> exposed to userspace then maybe these attributes become per-CPU group
> instead of global?
>
> Anyhow, lots to think about for big.LITTLE.

Currently, Linaro is looking for two solutions to big.LITTLE:
- Make scheduler aware of big.LITTLE and so, cpufreq isn't required to
do anything
  special (Long term solution, work in progress)
- Hide big.LITTLE from scheduler and perform big-LITTLE switching using cpufreq.
  This is a short term solution and Linaro has released its first
version already (Private
  to members) and this patch came out of the work on that release.

--
viresh

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