Re: [Xen-devel] [PATCH 0/9] Porting the intel_pstate driver to Xen

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.04.15 at 13:53, <wei.w.wang@xxxxxxxxx> wrote:
> On 24/04/2015 18:20, Jan Beulich wrote
>> >>> On 24.04.15 at 12:07, <wei.w.wang@xxxxxxxxx> wrote:
>> > On 24/04/2015 17:56, Jan Beulich wrote:
>> >> >>> On 24.04.15 at 11:46, <wei.w.wang@xxxxxxxxx> wrote:
>> >> > On 24/04/2015 17:11, Jan Beulich wrote:
>> >> >> >>> On 24.04.15 at 10:32, <wei.w.wang@xxxxxxxxx> wrote:
>> >> >> I think at the very least from a user interface perspective (e.g.
>> >> >> the xenpm
>> >> >> tool) the meaning of the old governor names should be retained as
>> >> >> much as possible.
>> >> >
>> >> > Ok. I am simply using the name "internal" for user tools. Please
>> >> > see the example below:
>> >> >
>> >> > scaling_driver           : intel_pstate
>> >> > scaling_avail_gov    : internal
>> >> > current_governor    : internal
>> >>
>> >> But xenpm's set-scaling-governor command should still do something
>> >> useful for the currently available governor options. And with that,
>> >> showing "internal" in its output may also end up being confusing (at
>> >> least I am already being confused).
>> >
>> > The case is similar to that in the kernel. Xen has two pstate driver,
>> > but only one can be loaded. When the intel_pstate driver is used
>> ("scaling_driver
>> >  : intel_pstate "),   xenpm's set-scaling-governor will not take effect, 
> since
>> > the intel_pstate only implements its internal governor.
>> 
>> But that's precisely what I'm asking to be changed: Even if internally is 
> uses
>> its own governor, the user interface of the tool should still be usable to
>> achieve similar effects.
> 
> Yes, we should change that if we remain two governors in the intel_pstate 
> driver.
> But as we discussed before, the internal Performance governor seems 
> redundant and can be removed. In that case, there is no other option of 
> governors that be selected by the user via set-scaling-governor.

I'm not sure how else to express what I want (no matter how many
internal governors the intel_pstate driver has).

xenpm set-scaling-governor powersave
xenpm set-scaling-governor ondemand
xenpm set-scaling-governor performance

each should switch the system into a respective state, no matter
whether internally to the driver this means a change of governors
or just a modification to {min,max}_pct.

And obtaining the current state after any of the above should
show the same governor in use that was set (and not "internal"),
again no matter how this is being achieved internally to the
driver.

Jan


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