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From: Ionela Voinescu <ionela.voinescu@arm.com>
To: rjw@rjwysocki.net, viresh.kumar@linaro.org,
	dietmar.eggemann@arm.com, catalin.marinas@arm.com,
	sudeep.holla@arm.com, will@kernel.org, linux@armlinux.org.uk
Cc: mingo@redhat.com, peterz@infradead.org, linux-pm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, ionela.voinescu@arm.com
Subject: [PATCH v2 3/7] arch_topology: disable frequency invariance for CONFIG_BL_SWITCHER
Date: Wed, 22 Jul 2020 10:37:28 +0100	[thread overview]
Message-ID: <20200722093732.14297-4-ionela.voinescu@arm.com> (raw)
In-Reply-To: <20200722093732.14297-1-ionela.voinescu@arm.com>

big.LITTLE switching complicates the setting of a correct cpufreq-based
frequency invariance scale factor due to (as observed in
drivers/cpufreq/vexpress-spc-cpufreq.c):
 - Incorrect current and maximum frequencies as a result of the
   exposure of a virtual frequency table to the cpufreq core,
 - Missed updates as a result of asynchronous frequency adjustments
   caused by frequency changes in other CPU pairs.

Given that its functionality is atypical in regards to frequency
invariance and this is an old technology, disable frequency
invariance for when big.LITTLE switching is configured in to prevent
incorrect scale setting.

Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Suggested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
---
 drivers/base/arch_topology.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 4d0a0038b476..708768f528dc 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -27,6 +27,7 @@ __weak bool arch_freq_counters_available(struct cpumask *cpus)
 }
 DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE;
 
+#ifndef CONFIG_BL_SWITCHER
 void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
 			 unsigned long max_freq)
 {
@@ -46,6 +47,7 @@ void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
 	for_each_cpu(i, cpus)
 		per_cpu(freq_scale, i) = scale;
 }
+#endif
 
 DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
 
-- 
2.17.1


  parent reply	other threads:[~2020-07-22  9:38 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-22  9:37 [PATCH v2 0/7] cpufreq: improve frequency invariance support Ionela Voinescu
2020-07-22  9:37 ` [PATCH v2 1/7] cpufreq: move invariance setter calls in cpufreq core Ionela Voinescu
2020-07-27 13:48   ` Rafael J. Wysocki
2020-07-29  9:03     ` Ionela Voinescu
2020-07-30  3:41     ` Viresh Kumar
2020-08-03 13:26       ` Ionela Voinescu
2020-08-03 13:46         ` Rafael J. Wysocki
2020-08-03 14:16           ` Ionela Voinescu
2020-07-22  9:37 ` [PATCH v2 2/7] cpufreq: set invariance scale factor on transition end Ionela Voinescu
2020-07-27 13:52   ` Rafael J. Wysocki
2020-07-29  9:14     ` Ionela Voinescu
2020-07-30  4:13   ` Viresh Kumar
2020-08-03 13:58     ` Ionela Voinescu
2020-08-04  6:26       ` Viresh Kumar
2020-08-05 10:35         ` Ionela Voinescu
2020-07-22  9:37 ` Ionela Voinescu [this message]
2020-07-30  4:24   ` [PATCH v2 3/7] arch_topology: disable frequency invariance for CONFIG_BL_SWITCHER Viresh Kumar
2020-07-30 10:29     ` Dietmar Eggemann
2020-07-31 15:48       ` Sudeep Holla
2020-08-03 14:39         ` Ionela Voinescu
2020-08-04  6:30       ` Viresh Kumar
2020-08-10  9:01         ` Ionela Voinescu
2020-07-22  9:37 ` [PATCH v2 4/7] cpufreq: report whether cpufreq supports Frequency Invariance (FI) Ionela Voinescu
2020-07-27 14:02   ` Rafael J. Wysocki
2020-07-29 14:39     ` Ionela Voinescu
2020-07-30  4:43   ` Viresh Kumar
2020-08-03 15:24     ` Ionela Voinescu
2020-08-04  6:46       ` Viresh Kumar
2020-08-05 10:35         ` Ionela Voinescu
2020-07-22  9:37 ` [PATCH v2 5/7] arch_topology,cpufreq,sched/core: constify arch_* cpumasks Ionela Voinescu
2020-07-30 11:43   ` Catalin Marinas
2020-07-22  9:37 ` [PATCH v2 6/7] arch_topology,arm,arm64: define arch_scale_freq_invariant() Ionela Voinescu
2020-07-30 11:44   ` Catalin Marinas
2020-07-22  9:37 ` [PATCH v2 7/7] cpufreq: make schedutil the default for arm and arm64 Ionela Voinescu
2020-07-30  4:54   ` Viresh Kumar

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