[Skiboot] [PATCH] SLW: Add idle state stop5 for DD2.0 and above

[Nicholas Piggin]

On Tue, 14 Nov 2017 18:52:09 +1100
Stewart Smith <stewart at linux.vnet.ibm.com> wrote:

> Akshay Adiga <akshay.adiga at linux.vnet.ibm.com> writes:
> > Adding stop5 idle state with rough residency and latency numbers.  
> 
> How stable has stop5 proved? I gather this patch is an indication that
> we're fairly confident we have stop5 working well enough for an OS to
> use?
> 
> Is there some way we could write a test from userspace to force a core
> into stop5 and out again a bunch of times? Maybe disable all other stop
> states, do nothing on it and then check?
> 

Yes, disable all other stop states. You can do it at runtime with
/sys/devices/system/cpu/cpu*/cpuidle/state*/disable

You can then use context switch benchmark or some IO traffic etc
to really hammer it.

Thanks,
Nick