From: Naveen Krishna Chatradhi <nchatrad@amd.com>
To: linux-hwmon@vger.kernel.org
Cc: naveenkrishna.ch@gmail.com,
Naveen Krishna Chatradhi <nchatrad@amd.com>,
Guenter Roeck <linux@roeck-us.net>
Subject: [PATCH 2/3] hwmon: (amd_energy) Add documentation
Date: Fri, 1 May 2020 23:20:02 +0530 [thread overview]
Message-ID: <20200501175003.28613-2-nchatrad@amd.com> (raw)
In-Reply-To: <20200501175003.28613-1-nchatrad@amd.com>
Document amd_energy driver with all chips supported by it.
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
---
Changes in v5: None
Documentation/hwmon/amd_energy.rst | 100 +++++++++++++++++++++++++++++
Documentation/hwmon/index.rst | 1 +
2 files changed, 101 insertions(+)
create mode 100644 Documentation/hwmon/amd_energy.rst
diff --git a/Documentation/hwmon/amd_energy.rst b/Documentation/hwmon/amd_energy.rst
new file mode 100644
index 000000000000..2216c8b13e58
--- /dev/null
+++ b/Documentation/hwmon/amd_energy.rst
@@ -0,0 +1,100 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver amd_energy
+==========================
+
+Supported chips:
+
+* AMD Family 17h Processors
+
+ Prefix: 'amd_energy'
+
+ Addresses used: RAPL MSRs
+
+ Datasheets:
+
+ - Processor Programming Reference (PPR) for AMD Family 17h Model 01h, Revision B1 Processors
+
+ https://developer.amd.com/wp-content/resources/55570-B1_PUB.zip
+
+ - Preliminary Processor Programming Reference (PPR) for AMD Family 17h Model 31h, Revision B0 Processors
+
+ https://developer.amd.com/wp-content/resources/56176_ppr_Family_17h_Model_71h_B0_pub_Rev_3.06.zip
+
+Author: Naveen Krishna Chatradhi <nchatrad@amd.com>
+
+Description
+-----------
+
+The Energy driver exposes the energy counters that are
+reported via the Running Average Power Limit (RAPL)
+Model-specific Registers (MSRs) via the hardware monitor
+(HWMON) sysfs interface.
+
+1. Power, Energy and Time Units
+ MSR_RAPL_POWER_UNIT/ C001_0299:
+ shared with all cores in the socket
+
+2. Energy consumed by each Core
+ MSR_CORE_ENERGY_STATUS/ C001_029A:
+ 32-bitRO, Accumulator, core-level power reporting
+
+3. Energy consumed by Socket
+ MSR_PACKAGE_ENERGY_STATUS/ C001_029B:
+ 32-bitRO, Accumulator, socket-level power reporting,
+ shared with all cores in socket
+
+These registers are updated every 1ms and cleared on
+reset of the system.
+
+Energy Caluclation
+------------------
+
+Energy information (in Joules) is based on the multiplier,
+1/2^ESU; where ESU is an unsigned integer read from
+MSR_RAPL_POWER_UNIT register. Default value is 10000b,
+indicating energy status unit is 15.3 micro-Joules increment.
+
+Reported values are scaled as per the formula
+
+scaled value = ((1/2^ESU) * (Raw value) * 1000000UL) in Joules
+
+Users calculate power for a given domain by calculating
+ dEnergy/dTime for that domain.
+
+Socket energy accumulation
+--------------------------
+
+Current Socket energy status register is 32bit, assuming a 240W
+system, the register would wrap around in
+
+ 2^32*15.3 e-6/240 = 273.80416512 secs to wrap(~4.5 mins)
+
+To improve the wrap around time, a kernel thread is implemented
+to accumulate the socket energy counter to a 64-bit counter. The
+kernel thread starts running during probe, wakes up at 100secs
+and stops running in remove.
+
+A socket energy read would return the current register value
+added to the respective energy accumulator.
+
+Sysfs attributes
+----------------
+
+=============== ======== =====================================
+Attribute Label Description
+=============== ======== =====================================
+
+* For index N between [1] and [nr_cpus]
+
+=============== ======== ======================================
+energy[N]_input EcoreX Core Energy X = [0] to [nr_cpus - 1]
+ Measured input core energy
+=============== ======== ======================================
+
+* For N between [nr_cpus] and [nr_cpus + nr_socks]
+
+=============== ======== ======================================
+energy[N]_input EsocketX Socket Energy X = [0] to [nr_socks -1]
+ Measured input socket energy
+=============== ======== ======================================
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 8ef62fd39787..fc4b89810e67 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -39,6 +39,7 @@ Hardware Monitoring Kernel Drivers
adt7470
adt7475
amc6821
+ amd_energy
asb100
asc7621
aspeed-pwm-tacho
--
2.17.1
next prev parent reply other threads:[~2020-05-01 17:50 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-01 17:50 [PATCH 1/3] hwmon: Add amd_energy driver to report energy counters Naveen Krishna Chatradhi
2020-05-01 17:50 ` Naveen Krishna Chatradhi [this message]
2020-05-06 16:33 ` [PATCH 2/3] hwmon: (amd_energy) Add documentation Guenter Roeck
2020-05-06 17:11 ` Naveen Krishna Ch
2020-05-06 19:27 ` Guenter Roeck
2020-05-11 16:49 ` Naveen Krishna Ch
2020-05-01 17:50 ` [PATCH 3/3] MAINTAINERS: add entry for AMD energy driver Naveen Krishna Chatradhi
2020-05-06 16:23 ` [PATCH 1/3] hwmon: Add amd_energy driver to report energy counters Guenter Roeck
2020-05-06 17:06 ` Naveen Krishna Ch
2020-05-06 18:32 ` Guenter Roeck
2020-05-14 15:56 ` Naveen Krishna Ch
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