linux-kernel - Re: [RFC/RFT][PATCH] cpufreq: intel_pstate: Accept passive mode with HWP enabled

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Date:   Sun, 31 May 2020 12:28:46 -0700
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     Doug Smythies <dsmythies@...us.net>,
        "'Rafael J. Wysocki'" <rjw@...ysocki.net>
Cc:     'LKML' <linux-kernel@...r.kernel.org>,
        'Len Brown' <len.brown@...el.com>,
        'Peter Zijlstra' <peterz@...radead.org>,
        'Giovanni Gherdovich' <ggherdovich@...e.cz>,
        'Francisco Jerez' <francisco.jerez.plata@...el.com>,
        'Linux PM' <linux-pm@...r.kernel.org>
Subject: Re: [RFC/RFT][PATCH] cpufreq: intel_pstate: Accept passive mode
 with HWP enabled

On Sun, 2020-05-31 at 11:59 -0700, Srinivas Pandruvada wrote:
> On Sun, 2020-05-31 at 11:06 -0700, Doug Smythies wrote:
> > Hi Srinivas,
> > 
> > Thanks you for your quick reply.
> > 
> > On 2020.05.31 09:54 Srinivas Pandruvada wrote
> > > On Sun, 2020-05-31 at 09:39 -0700, Doug Smythies wrote:
> > > > Event begins at 17.456 seconds elapsed time.
> > > > Previous event was about 107 milliseconds ago.
> > > > 
> > > > Old min ; new min ; freq GHz; load % ; duration mS
> > > > 27      ; 28      ; 4.60    ; 68.17  ; 10.226
> > > > 28      ; 26      ; 4.53    ; 57.47  ; 10.005
> > > 
> > > Seems you hit power/thermal limit
> > 
> > No.
> > 
> > I am nowhere near any power limit at all.
> > I have meticulously configured and tested the thermal management of
> > this computer.
> > I never ever hit a thermal limit and have TDP set such that the
> > processor
> > temperature never exceeds about 75 degrees centigrade.
> > 
> > There should never be throttling involved in these experiments.
> > I can achieve throttling when compiling the kernel and with
> > torture test mode on the mprime test (other CPU stressors,
> > including my own, are not as good at generating heat as
> > mprime).
> > 
> > This system can run indefinitely at 99.9 watts processor package
> > power.
> > Example (turbostat, steady state, CPU freq throttled to 4.04 GHz):
> > 
> > doug@s18:~$ sudo ~/turbostat --Summary --quiet --show
> > Busy%,Bzy_MHz,PkgTmp,PkgWatt,GFXWatt,IRQ --interval 12
> > Busy%   Bzy_MHz IRQ     PkgTmp  PkgWatt GFXWatt
> > 100.21  4045    72231   66      99.93   0.00
> > 100.21  4043    72239   65      99.92   0.00
> > 
> > > Is this some Lenovo system?
> > 
> > No. The web page version of my original e-mail has
> > a link to the test computer hardware profile.
> > 
> > The motherboard is ASUS PRIME Z390-P.
> > 
> 
> OK, this seems a desktop system.
> 
> > > If you disable HWP you don't see that?
> > 
> > Correct.
> > 
> > > What is the value of
> > > cat /sys/bus/pci/devices/0000\:00\:04.0/tcc_offset_degree_celsius
> > 
> > ? "No such file or directory"
> > 
> > > cat /sys/class/powercap/intel-rapl-mmio/intel-rapl-
> > > mmio:0/constraint_0_power_limit_uw
> You may not have
> CONFIG_INT340X_THERMAL=y
> 
> What is
> #rdmsr 0x1a2
> 
> Try changing energy_perf_bias and see if it helps here.
> 
Also if
MSR 0x1FC bit 19 is 0, change to 1.

Thanks,
Srinivas

> Thanks,
> Srinivas
> 
> 
> > ? "No such file or directory"
> >  
> > > You may want to run
> > > Try running dptfxtract once.
> > 
> > No, I am not going to.
> > 
> > I am not running thermald. Eventually I will, as a backup
> > in case of cooling failure, so as not to hit the processor limit
> > shutdown. I just haven't done it yet.
> > 
> > > Then try to get again
> > > 
> > > cat /sys/bus/pci/devices/0000\:00\:04.0/tcc_offset_degree_celsius
> > > cat /sys/class/powercap/intel-rapl-mmio/intel-rapl-
> > > mmio:0/constraint_0_power_limit_uw
> > > 
> > > 
> > > Thanks,
> > > Srinivas