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From: Peter Zijlstra <peterz@infradead.org>
To: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: tglx@linutronix.de, mingo@redhat.com, bp@suse.de,
	lenb@kernel.org, rjw@rjwysocki.net, mgorman@techsingularity.net,
	x86@kernel.org, linux-pm@vger.kernel.org,
	viresh.kumar@linaro.org, juri.lelli@arm.com,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC/RFT] [PATCH 02/10] cpufreq: intel_pstate: Conditional frequency invariant accounting
Date: Wed, 16 May 2018 09:29:29 +0200	[thread overview]
Message-ID: <20180516072929.GN12235@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180516071640.GU12217@hirez.programming.kicks-ass.net>

On Wed, May 16, 2018 at 09:16:40AM +0200, Peter Zijlstra wrote:
> On Tue, May 15, 2018 at 09:49:03PM -0700, Srinivas Pandruvada wrote:
> > intel_pstate has two operating modes: active and passive. In "active"
> > mode, the in-built scaling governor is used and in "passive" mode,
> > the driver can be used with any governor like "schedutil". In "active"
> > mode the utilization values from schedutil is not used and there is
> > a requirement from high performance computing use cases, not to read
> > any APERF/MPERF MSRs. In this case no need to use CPU cycles for
> > frequency invariant accounting by reading APERF/MPERF MSRs.
> > With this change frequency invariant account is only enabled in
> > "passive" mode.
> 
> WTH is active/passive? Is passive when we select performance governor?

Bah, I cannot read it seems. active is when we use the intel_pstate
governor and passive is when we use schedutil and only use intel_pstate
as a driver.

> Also; you have to explain why using APERF/MPERF is bad in that case. Why
> do they care if we read those MSRs during the tick?

That still stands.. this needs to be properly explained.

  reply	other threads:[~2018-05-16  7:29 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-16  4:49 [RFC/RFT] [PATCH 00/10] Intel_pstate: HWP Dynamic performance boost Srinivas Pandruvada
2018-05-16  4:49 ` [RFC/RFT] [PATCH 01/10] x86,sched: Add support for frequency invariance Srinivas Pandruvada
2018-05-16  9:56   ` Peter Zijlstra
2018-05-16  4:49 ` [RFC/RFT] [PATCH 02/10] cpufreq: intel_pstate: Conditional frequency invariant accounting Srinivas Pandruvada
2018-05-16  7:16   ` Peter Zijlstra
2018-05-16  7:29     ` Peter Zijlstra [this message]
2018-05-16  9:07       ` Rafael J. Wysocki
2018-05-16 17:32         ` Srinivas Pandruvada
2018-05-16 15:19   ` Juri Lelli
2018-05-16 15:47     ` Peter Zijlstra
2018-05-16 16:31       ` Juri Lelli
2018-05-17 10:59         ` Juri Lelli
2018-05-17 15:04           ` Juri Lelli
2018-05-17 15:41             ` Srinivas Pandruvada
2018-05-17 16:16               ` Peter Zijlstra
2018-05-17 16:42                 ` Srinivas Pandruvada
2018-05-17 16:56                   ` Rafael J. Wysocki
2018-05-17 18:28                     ` Peter Zijlstra
2018-05-18  7:36                       ` Rafael J. Wysocki
2018-05-18 10:57                       ` Patrick Bellasi
2018-05-18 11:29                         ` Peter Zijlstra
2018-05-18 13:33                           ` Patrick Bellasi
2018-05-30 16:57                             ` Patrick Bellasi
2018-05-18 14:09                           ` Valentin Schneider
2018-05-16 15:58     ` Srinivas Pandruvada
2018-05-16  4:49 ` [RFC/RFT] [PATCH 03/10] cpufreq: intel_pstate: Utility functions to boost HWP performance limits Srinivas Pandruvada
2018-05-16  7:22   ` Peter Zijlstra
2018-05-16  9:15     ` Rafael J. Wysocki
2018-05-16 10:43       ` Peter Zijlstra
2018-05-16 15:39         ` Srinivas Pandruvada
2018-05-16 15:41     ` Srinivas Pandruvada
2018-05-16  4:49 ` [RFC/RFT] [PATCH 04/10] cpufreq: intel_pstate: Add update_util_hook for HWP Srinivas Pandruvada
2018-05-16  4:49 ` [RFC/RFT] [PATCH 05/10] cpufreq: intel_pstate: HWP boost performance on IO Wake Srinivas Pandruvada
2018-05-16  7:37   ` Peter Zijlstra
2018-05-16 17:55     ` Srinivas Pandruvada
2018-05-17  8:19       ` Peter Zijlstra
2018-05-16  9:45   ` Rafael J. Wysocki
2018-05-16 19:28     ` Srinivas Pandruvada
2018-05-16  4:49 ` [RFC/RFT] [PATCH 06/10] cpufreq / sched: Add interface to get utilization values Srinivas Pandruvada
2018-05-16  6:40   ` Viresh Kumar
2018-05-16 22:25     ` Srinivas Pandruvada
2018-05-16  8:11   ` Peter Zijlstra
2018-05-16 22:40     ` Srinivas Pandruvada
2018-05-17  7:50       ` Peter Zijlstra
2018-05-16  4:49 ` [RFC/RFT] [PATCH 07/10] cpufreq: intel_pstate: HWP boost performance on busy task migrate Srinivas Pandruvada
2018-05-16  9:49   ` Rafael J. Wysocki
2018-05-16 20:59     ` Srinivas Pandruvada
2018-05-16  4:49 ` [RFC/RFT] [PATCH 08/10] cpufreq: intel_pstate: Dyanmically update busy pct Srinivas Pandruvada
2018-05-16  7:43   ` Peter Zijlstra
2018-05-16  7:47   ` Peter Zijlstra
2018-05-16  4:49 ` [RFC/RFT] [PATCH 09/10] cpufreq: intel_pstate: New sysfs entry to control HWP boost Srinivas Pandruvada
2018-05-16  4:49 ` [RFC/RFT] [PATCH 10/10] cpufreq: intel_pstate: enable boost for SKX Srinivas Pandruvada
2018-05-16  7:49   ` Peter Zijlstra
2018-05-16 15:46     ` Srinivas Pandruvada
2018-05-16 15:54       ` Peter Zijlstra
2018-05-17  0:52         ` Srinivas Pandruvada
2018-05-16  6:49 ` [RFC/RFT] [PATCH 00/10] Intel_pstate: HWP Dynamic performance boost Juri Lelli
2018-05-16 15:43   ` Srinivas Pandruvada

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