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From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
To: "Hernandez Lopez, Fabiola" <fabiola.hernandez.lopez@intel.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>
Subject: Re: Frequency not returning to fixed value after AVX workload
Date: Mon, 14 Oct 2019 14:23:15 -0700
Message-ID: <e7e89cd85fb5d367338491651b36cc912967edab.camel@linux.intel.com> (raw)
In-Reply-To: <67737C20FC7E4D44B44817ABFA5B1DCE6EC020E9@CRSMSX104.amr.corp.intel.com>

On Mon, 2019-10-14 at 21:11 +0000, Hernandez Lopez, Fabiola wrote:
> How do you measure the frequency?
Do whatever you are doing to get to your problem state and while doing
the test run in another window:

#turbostat

Attach the output.

Thanks,
Srinivas

> With lscpu.
> 
> What exactly do you do to get the expected frequency back?
> A script is used that sets the frequency with
> /sys/devices/system/cpu/cpu*/cpufreq/scaling_setspeed
> 
> Is the target frequency in the turbo range?
> No, the target frequency is the same as the base processor frequency:
> 2.4GHz. The max turbo frequency for this CPU si 3.9 GHz.
> This has been tested with turbo boost enabled and disabled. 
> 
> This behavior is very sporadic: < 10%
> 
> Thanks,
> Fabiola
> 
> -----Original Message-----
> From: Rafael J. Wysocki [mailto:rjw@rjwysocki.net] 
> Sent: Monday, October 14, 2019 4:45 AM
> To: Hernandez Lopez, Fabiola <fabiola.hernandez.lopez@intel.com>
> Cc: linux-pm@vger.kernel.org; Srinivas Pandruvada <
> srinivas.pandruvada@linux.intel.com>
> Subject: Re: Frequency not returning to fixed value after AVX
> workload
> 
> On Friday, October 11, 2019 7:45:55 PM CEST Hernandez Lopez, Fabiola
> wrote:
> > Hi,
> > 
> > We are seeing an unexpected behavior after applying AVX workloads. 
> > After setting the CPU frequency to a fixed value with CPU Freq - 
> > userspace governor and applying heavy AVX workloads, the CPU
> > frequency 
> > is decreased (as expected) but it never returns to the previously
> > established value.
> 
> How do you measure the frequency?
> 
> > This does not happen on all cores, only on a single core. The only
> > way 
> > to return to the desired frequency is by setting it through the 
> > command line again.
> 
> What exactly do you do to get the expected frequency back?
> 
> > We are wondering how can this change in frequency happen.
> 
> Is the target frequency in the turbo range?
> 
> 
> 


  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-11 17:45 Hernandez Lopez, Fabiola
2019-10-14  9:44 ` Rafael J. Wysocki
2019-10-14 21:11   ` Hernandez Lopez, Fabiola
2019-10-14 21:23     ` Srinivas Pandruvada [this message]
2019-10-23 18:26       ` Hernandez Lopez, Fabiola

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