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* [PATCH v4 0/4] PM / QoS: Restore DEV_PM_QOS_MIN/MAX_FREQUENCY
@ 2019-11-26 15:17 Leonard Crestez
  2019-11-26 15:17 ` [PATCH v4 1/4] PM / QoS: Initial kunit test Leonard Crestez
                   ` (4 more replies)
  0 siblings, 5 replies; 13+ messages in thread
From: Leonard Crestez @ 2019-11-26 15:17 UTC (permalink / raw)
  To: Rafael J. Wysocki, Matthias Kaehlcke, Chanwoo Choi
  Cc: Viresh Kumar, MyungJoo Ham, Kyungmin Park, Artur Świgoń,
	Angus Ainslie, Brendan Higgins, linux-kselftest, kunit-dev,
	linux-pm, linux-imx

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 (latest version, no dependencies outside this series):

	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
will most likely be empty when the target device is deleted. Series follows
current pattern for dev_pm_qos.

First two patches can be applied separately.

Changes since v3:
* Fix s/QOS/QoS in patch 2 title
* Improves comments in kunit test
* Fix assertions after freq_qos_remove_request
* Remove (c) from NXP copyright header
* Wrap long lines in qos.c to be under 80 chars. This fixes checkpatch but the
rule is already broken by code in the files.
* Collect reviews
Link to v3: https://patchwork.kernel.org/cover/11260627/

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 and another recent fix. Testing this should be easier!
Link to v2: https://patchwork.kernel.org/cover/11250413/

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 | 117 ++++++++++++++++++++++++++++++++++
 drivers/base/power/qos.c      |  73 +++++++++++++++++++--
 include/linux/pm_qos.h        |  86 ++++++++++++++-----------
 kernel/power/qos.c            |   4 +-
 6 files changed, 242 insertions(+), 43 deletions(-)
 create mode 100644 drivers/base/power/qos-test.c

-- 
2.17.1


^ permalink raw reply	[flat|nested] 13+ messages in thread

end of thread, other threads:[~2019-12-02 16:49 UTC | newest]

Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-11-26 15:17 [PATCH v4 0/4] PM / QoS: Restore DEV_PM_QOS_MIN/MAX_FREQUENCY Leonard Crestez
2019-11-26 15:17 ` [PATCH v4 1/4] PM / QoS: Initial kunit test Leonard Crestez
2019-11-26 20:04   ` Matthias Kaehlcke
2019-11-27 23:40     ` Leonard Crestez
2019-12-02 16:49       ` Brendan Higgins
2019-11-26 15:17 ` [PATCH v4 2/4] PM / QoS: Redefine FREQ_QOS_MAX_DEFAULT_VALUE to S32_MAX Leonard Crestez
2019-11-26 15:17 ` [PATCH v4 3/4] PM / QoS: Reorder pm_qos/freq_qos/dev_pm_qos structs Leonard Crestez
2019-11-26 15:17 ` [PATCH v4 4/4] PM / QoS: Restore DEV_PM_QOS_MIN/MAX_FREQUENCY Leonard Crestez
2019-11-26 21:01   ` Matthias Kaehlcke
2019-11-29  5:55     ` Leonard Crestez
2019-11-29 11:34 ` [PATCH v4 0/4] " Rafael J. Wysocki
2019-11-29 14:20   ` Leonard Crestez
2019-12-02  1:24     ` Chanwoo Choi

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