From: Leonard Crestez <leonard.crestez@nxp.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Matthias Kaehlcke <mka@chromium.org>
Cc: "Viresh Kumar" <viresh.kumar@linaro.org>,
"MyungJoo Ham" <myungjoo.ham@samsung.com>,
"Kyungmin Park" <kyungmin.park@samsung.com>,
"Chanwoo Choi" <cw00.choi@samsung.com>,
"Artur Świgoń" <a.swigon@partner.samsung.com>,
"Angus Ainslie" <angus@akkea.ca>,
"Brendan Higgins" <brendanhiggins@google.com>,
linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
linux-pm@vger.kernel.org, linux-imx@nxp.com
Subject: [PATCH v3 0/4] PM: QoS: Restore DEV_PM_QOS_MIN/MAX_FREQUENCY
Date: Mon, 25 Nov 2019 18:42:15 +0200 [thread overview]
Message-ID: <cover.1574699610.git.leonard.crestez@nxp.com> (raw)
Support for frequency limits in dev_pm_qos was removed when cpufreq was
switched to freq_qos, this series attempts to restore it by
reimplementing on top of freq_qos.
Discussion about removal is here:
https://lore.kernel.org/linux-pm/VI1PR04MB7023DF47D046AEADB4E051EBEE680@VI1PR04MB7023.eurprd04.prod.outlook.com/T/#u
The cpufreq core switched away because it needs contraints at the level
of a "cpufreq_policy" which cover multiple cpus so dev_pm_qos coupling
to struct device was not useful. Cpufreq could only use dev_pm_qos by
implementing an additional layer of aggregation anyway.
However in the devfreq subsystem scaling is always performed on a per-device
basis so dev_pm_qos is a very good match. Support for dev_pm_qos in devfreq
core is here:
https://patchwork.kernel.org/cover/11252409/
That series is RFC mostly because it needs these PM core patches.
Earlier versions got entangled in some locking cleanups but those are
not strictly necessary to get dev_pm_qos functionality.
In theory if freq_qos is extended to handle conflicting min/max values then
this sharing would be valuable. Right now freq_qos just ties two unrelated
pm_qos aggregations for min and max freq.
---
This is implemented by embeding a freq_qos_request inside dev_pm_qos_request:
the data field was already an union in order to deal with flag requests.
The internal freq_qos_apply is exported so that it can be called from
dev_pm_qos apply_constraints.
The dev_pm_qos_constraints_destroy function has no obvious equivalent in
freq_qos and the whole approach of "removing requests" is somewhat dubios:
request objects should be owned by consumers and the list of qos requests
should be empty when the target device is deleted.
Changes since v2:
* #define PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE FREQ_QOS_MAX_DEFAULT_VALUE
* #define FREQ_QOS_MAX_DEFAULT_VALUE S32_MAX (in new patch)
* Add initial kunit test for freq_qos, validating the MAX_DEFAULT_VALUE found
by Matthias.
Link to v2: https://patchwork.kernel.org/cover/11250413/
First two patches can be applied separated
Changes since v1:
* Don't rename or EXPORT_SYMBOL_GPL the freq_qos_apply function; just
drop the static marker.
Link to v1: https://patchwork.kernel.org/cover/11212887/
Leonard Crestez (4):
PM / QoS: Initial kunit test
PM / QOS: Redefine FREQ_QOS_MAX_DEFAULT_VALUE to S32_MAX
PM / QoS: Reorder pm_qos/freq_qos/dev_pm_qos structs
PM / QoS: Restore DEV_PM_QOS_MIN/MAX_FREQUENCY
drivers/base/Kconfig | 4 ++
drivers/base/power/Makefile | 1 +
drivers/base/power/qos-test.c | 116 ++++++++++++++++++++++++++++++++++
drivers/base/power/qos.c | 69 ++++++++++++++++++--
include/linux/pm_qos.h | 86 ++++++++++++++-----------
kernel/power/qos.c | 4 +-
6 files changed, 237 insertions(+), 43 deletions(-)
create mode 100644 drivers/base/power/qos-test.c
--
2.17.1
next reply other threads:[~2019-11-25 16:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-25 16:42 Leonard Crestez [this message]
2019-11-25 16:42 ` [PATCH v3 1/4] PM / QoS: Initial kunit test Leonard Crestez
2019-11-25 20:19 ` Matthias Kaehlcke
2019-11-26 12:36 ` Leonard Crestez
2019-11-25 16:42 ` [PATCH v3 2/4] PM / QOS: Redefine FREQ_QOS_MAX_DEFAULT_VALUE to S32_MAX Leonard Crestez
2019-11-25 21:09 ` Matthias Kaehlcke
2019-11-25 16:42 ` [PATCH v3 3/4] PM / QoS: Reorder pm_qos/freq_qos/dev_pm_qos structs Leonard Crestez
2019-11-25 22:22 ` Matthias Kaehlcke
2019-11-25 16:42 ` [PATCH v3 4/4] PM / QoS: Restore DEV_PM_QOS_MIN/MAX_FREQUENCY Leonard Crestez
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