Re: [PATCH 0/2][RFC] ACPI / PM: Disable MSR T-state after resumed

[Chen Yu <yu.c.chen@intel.com>]

Hi Doug,
On Fri, Aug 25, 2017 at 02:40:19PM -0700, Doug Smythies wrote:
> On 2017.08.25 09:43 Chen Yu wrote:
> 
> > There is a growing number of reports that the MSR throttling has
> > been enabled after resumed back from suspend to ram, which impacts
> > the system performance. This patchset tries to address this issue
> > by turning off the T-state after resumed back.
> >
> > Chen Yu (2):
> >  ACPI / PM: Reuse the acpi_sleep_syscore_ops for future requirement
> >  ACPI / PM: Disable the MSR T-state during CPU online
> >
> > drivers/acpi/sleep.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> > 1 file changed, 58 insertions(+), 2 deletions(-)
> 
> Hi Chen,
> 
> I'll just copy and paste what I wrote in a couple of the bug reports ([1] for example) a couple of days ago:
> 
> > I believe that pending changes to the intel-pstate CPU frequency scaling driver,
> > proposed by Rafael, I think for kernel 4.14-rc1, will eliminate the ongoing
> > troubles with Clock Modulation and the driver.
> >
> > I'm saying that the issue will no longer exist, and that the intel_pstate
> > CPU frequency scaling driver will respond "properly" to Clock Modulation events.
> > Of course, I'll check when kernel 4.14-rc1 becomes available, or before if I can
> > apply all the patches.
> >
> > For reference see the patch set related to:
> >
> > [PATCH 0/2] cpufreq: intel_pstate: Eliminate the PID controller
> > 2017.07.24 03:22 (or 10:22 UTC, I think)
> >
> > https://marc.info/?l=linux-pm&m=150093486908759&w=2
> > https://marc.info/?l=linux-pm&m=150093484308751&w=2
> > https://marc.info/?l=linux-pm&m=150093486808758&w=2
> 
> [1] https://bugzilla.kernel.org/show_bug.cgi?id=189861
> 
> 
I did not quite catup with the relationship between the intel_pstate
patch and the tstate patch here, if the Clock Modulation is enabled,
will the 'performance' governor be able to reach the maximum freq?
Besides, what if the user is using acpi-freq rather than intel_pstate?

Thanks,
	Yu