Re: [PATCH v2 0/4] cpufreq governors and Intel P state driver compatibility

From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
To: Prarit Bhargava <prarit@redhat.com>
Cc: rafael.j.wysocki@intel.com, viresh.kumar@linaro.org,
	linux-pm@vger.kernel.org, trenn@suse.de
Subject: Re: [PATCH v2 0/4]  cpufreq governors and Intel P state driver compatibility
Date: Tue, 08 Dec 2015 15:57:01 -0800	[thread overview]
Message-ID: <1449619021.3240.209.camel@spandruv-desk3.jf.intel.com> (raw)
In-Reply-To: <56676BAD.4030707@redhat.com>

On Tue, 2015-12-08 at 18:45 -0500, Prarit Bhargava wrote:
> 
> On 12/08/2015 05:31 PM, Srinivas Pandruvada wrote:
> > Intel P State driver implements two policies, performance and powersave.
> > The powersave policy is similar to ondemand cpufreq governor when using
> > acpi-cpufreq. This causes lots of confusion among users. This results
> > in invalid comparison of performance when acpi-cpufreq and Intel P state
> > performance is compared.
> > 
> > The reason Intel P state called powersave when it actually implemented
> > ondemand style P State selection, because the cpufreq core only allows
> > two generic policies "performance and powersave" for drivers which has
> > setpolicy() interface. All drivers using this interface are forced to
> > support these two policies.
> > 
> > This patchset adds feature to have configurable generic policies and
> > allows ondemand as one of the policy. With this approach, Intel P state
> > now adds support for ondemand policy and power save policy both in
> > addition to performance.
> 
Prarit,
> Srinivas, if I read the patchset correctly then this means that ondemand ==
> powersave ?
Yes. Will it cause problem to you?
> 
> If so, is the intention to one day remove powersave altogether and switch to
> only ondemand & performance?
Yes. But we can add powersave, which all requests P state to max
efficiency ratio. But I want to check, if it will this cause more
confusion.

Thanks,
Srinivas

> 
> P.