From: Mark Pearson <markpearson@lenovo.com>
To: <markpearson@lenovo.com>
Cc: <rjw@rjwysocki.net>, <hdegoede@redhat.com>,
<mgross@linux.intel.com>, <linux-acpi@vger.kernel.org>,
<mario.limonciello@dell.com>, <eliadevito@gmail.com>,
<hadess@hadess.net>, <bberg@redhat.com>,
<platform-driver-x86@vger.kernel.org>, <dvhart@infradead.org>
Subject: [PATCH v2 1/3] Documentation: Add documentation for new platform_profile sysfs attribute
Date: Sat, 14 Nov 2020 10:01:00 -0500 [thread overview]
Message-ID: <20201114150102.340618-1-markpearson@lenovo.com> (raw)
In-Reply-To: <markpearson@lenovo.com>
On modern systems the platform performance, temperature, fan and other
hardware related characteristics are often dynamically configurable. The
profile is often automatically adjusted to the load by somei
automatic-mechanism (which may very well live outside the kernel).
These auto platform-adjustment mechanisms often can be configured with
one of several 'platform-profiles', with either a bias towards low-power
consumption or towards performance (and higher power consumption and
thermals).
Introduce a new platform_profile sysfs API which offers a generic API for
selecting the performance-profile of these automatic-mechanisms.
Co-developed-by: Mark Pearson <markpearson@lenovo.com>
Signed-off-by: Mark Pearson <markpearson@lenovo.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
- updated to rst format
.../ABI/testing/sysfs-platform_profile.rst | 66 +++++++++++++++++++
1 file changed, 66 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-platform_profile.rst
diff --git a/Documentation/ABI/testing/sysfs-platform_profile.rst b/Documentation/ABI/testing/sysfs-platform_profile.rst
new file mode 100644
index 000000000000..5f7b2a94409b
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-platform_profile.rst
@@ -0,0 +1,66 @@
+=======================================================================
+ Platform Profile Selection (e.g. /sys/firmware/acpi/platform_profile)
+=======================================================================
+
+
+On modern systems the platform performance, temperature, fan and other
+hardware related characteristics are often dynamically configurable. The
+profile is often automatically adjusted to the load by some
+automatic mechanism (which may very well live outside the kernel).
+
+These auto platform adjustment mechanisms often can be configured with
+one of several platform profiles, with either a bias towards low power
+operation or towards performance.
+
+The purpose of the platform_profile attribute is to offer a generic sysfs
+API for selecting the platform profile of these automatic mechanisms.
+
+Note that this API is only for selecting the platform profile, it is
+NOT a goal of this API to allow monitoring the resulting performance
+characteristics. Monitoring performance is best done with device/vendor
+specific tools such as e.g. turbostat.
+
+Specifically when selecting a high performance profile the actual achieved
+performance may be limited by various factors such as: the heat generated
+by other components, room temperature, free air flow at the bottom of a
+laptop, etc. It is explicitly NOT a goal of this API to let userspace know
+about any sub-optimal conditions which are impeding reaching the requested
+performance level.
+
+Since numbers on their own cannot represent the multiple variables that a
+profile will adjust (power consumption, heat generation, etc) this API
+uses strings to describe the various profiles. To make sure that userspace
+gets a consistent experience this API document defines a fixed set of
+profile names. Drivers *must* map their internal profile representation
+onto this fixed set.
+
+
+If there is no good match when mapping then a new profile name may be
+added. Drivers which wish to introduce new profile names must:
+
+ 1. Explain why the existing profile names canot be used.
+ 2. Add the new profile name, along with a clear description of the
+ expected behaviour, to the documentation.
+
+:What: /sys/firmware/acpi/platform_profile_choices
+:Date: October 2020
+:Contact: Hans de Goede <hdegoede@redhat.com>
+:Description: This file contains a space-separated list of profiles supported for this device.
+
+ Drivers must use the following standard profile-names::
+
+ low-power: Low power consumption
+ cool: Cooler operation
+ quiet: Quieter operation
+ balanced: Balance between low power consumption and performance
+ performance: High performance operation
+
+ Userspace may expect drivers to offer more than one of these
+ standard profile names.
+
+:What: /sys/firmware/acpi/platform_profile
+:Date: October 2020
+:Contact: Hans de Goede <hdegoede@redhat.com>
+:Description: Reading this file gives the current selected profile for this
+ device. Writing this file with one of the strings from
+ available_profiles changes the profile to the new value.
--
2.25.1
next reply other threads:[~2020-11-14 15:01 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-14 15:01 Mark Pearson [this message]
2020-11-14 15:01 ` [PATCH v2 2/3] ACPI: platform-profile: Add platform profile support Mark Pearson
2020-11-14 15:10 ` Barnabás Pőcze
2020-11-15 0:40 ` [External] " Mark Pearson
2020-11-14 15:01 ` [PATCH v2 3/3] platform/x86: thinkpad_acpi: " Mark Pearson
2020-11-15 18:33 ` Barnabás Pőcze
2020-11-15 23:22 ` [External] " Mark Pearson
2020-11-16 10:41 ` Barnabás Pőcze
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