Re: [PATCH v2 1/2] cpufreq: Make iowait boost a policy option

From: Peter Zijlstra
Date: Fri May 19 2017 - 05:43:03 EST

On Thu, May 18, 2017 at 11:23:43PM -0700, Joel Fernandes wrote:
> Make iowait boost a cpufreq policy option and enable it for intel_pstate
> cpufreq driver. Governors like schedutil can use it to determine if
> boosting for tasks that wake up with p->in_iowait set is needed.

Rather than just flat out disabling the option, is there something
better we can do on ARM?

The reason for the IO-wait boost is to ensure we feed our external
devices data ASAP, this reduces wait times, increases throughput and
decreases the duration the devices have to operate.

I realize max freq/volt might not be the best option for you, but is
there another spot that would make sense? I can imagine you want to
return your MMC to low power state ASAP as well.

So rather than a disable flag, I would really rather see an IO-wait OPP
state selector or something.