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Subject[PATCH 00/10] Intel(R) Speed Select Technology
Date
Intel® Speed Select Technology (Intel® SST) — A powerful new collection of
features giving more granular control over CPU performance for optimized total
cost of ownership and performance. With Intel® SST, one server can be configured
for power and performance for variety of diverse workload requirements. In the
Linux submission code. we are using ISST to specify Intel® SST to avoid confusion
with existing use of SST for "Smart Sound Technology".

Refer to these links for overview of the technology released with some Intel® Xeon®
Scalable processor (5218N, 6230N, and 6252N):
https://www.intel.com/content/www/us/en/architecture-and-technology/speed-select-technology-article.html
https://builders.intel.com/docs/networkbuilders/intel-speed-select-technology-base-frequency-enhancing-performance.pdf

The next generation of Intel® Xeon® processors are adding more features to the
Intel® Speed Select Technology and allow dynamic configuration of these features
from OS-software level instead from BIOS. This submission is adding new features
and dynamic configuration capabilities .


Intel SST Features:

Intel® SST—Performance Profile (PP or perf-profile):
This feature allows one server to be configured for different workload requirements
instead of deploying different servers based on the workload requirement reducing total
cost of ownership. With a single server deployed, the same server can be reconfigured
dynamically to one of the supported profiles to suit the specific workload requirements.
This feature introduces a mechanism that allows multiple optimized performance profiles
per system via static and/or dynamic adjustment of TDP level and other performance
parameters.

Intel® SST—Core power (CP or core-power):
An Interface that allows user to define per core priority. This defines a mechanism
to distribute power among cores when there is a power constrained scenario. This defines
a class of service configuration. Each CPU core can be tied to a class of service and hence
an associated priority.

Intel® SST—Base Frequency (BF or base-freq):
The Intel® SST-BF feature lets user control and direct base frequency. If some critical
workload threads demand constant high guaranteed performance, then this feature can be
used to execute the thread at higher base frequency on specific set of CPUs.

Intel® SST—Turbo frequency (TF or turbo-freq):
Enables the ability to set different all core turbo ratio limits to cores based on the priority.
Using this features some cores can be configured to get higher turbo frequency by designating
them as high priority at the cost of lower or no turbo frequency on the low priority cores.

Implementation

The Intel® SST features are implemented in the firmware executing in the the power
management unit (we are calling PUNIT here for short). The mechanism to control these
features are specific to firmware implementation for Intel® Xeon® CPUs and are not architectural
features. The interface mechanism and semantics of the messages can change in future Xeon
CPUs. Hence there is minimal kernel implementation by offering direct communication
to PUNIT via set of IOCTLs. The actual messages which can be sent to PUNIT are specified
in the following document link:

https://github.com/intel/CommsPowerManagement/blob/master/intel_sst_os_interface/mailbox.md

The idea here is that user space software like cloud orchestration software based on their workload
requirement configure the system. There is a full featured "Intel Speed Select" utility
submitted to kernel power tools, which can be used to validate and exercise the features.

Types of PUNIT interfaces
There are two types of interfaces. One using Mail box communications, which is facilitated
by a PCI device or in some Xeon® CPUs using MSRs; and other using an MMIO interface, which is
used primarily for core prioritization. For hiding details a single character device is created
to handle IOCTLs. The following block diagram shows the implementation overview.


User User Space tool(intel-speed-select)/Cloud Orchestration software
IOCTLs
---------------------------------------character device------------------------------
kernel Common driver handling IOCTLs
Mail Box drivers(PCI & MSR) PCI MMIO driver
--------------------------------------------------------------------------
Hardware PUNIT



Srinivas Pandruvada (10):
platform/x86: ISST: Update ioctl-number.txt for Intel Speed Select
interface
platform/x86: ISST: Add common API to register and handle ioctls
platform/x86: ISST: Store per CPU information
platform/x86: ISST: Add IOCTL to Translate Linux logical CPU to PUNIT
CPU number
platform/x86: ISST: Add Intel Speed Select mmio interface
platform/x86: ISST: Add Intel Speed Select mailbox interface via PCI
platform/x86: ISST: Add Intel Speed Select mailbox interface via MSRs
platform/x86: ISST: Add Intel Speed Select PUNIT MSR interface
platform/x86: ISST: Restore state on resume
tools/power/x86: A tool to validate Intel Speed Select commands

Documentation/ioctl/ioctl-number.txt | 1 +
drivers/platform/x86/Kconfig | 2 +
drivers/platform/x86/Makefile | 1 +
.../x86/intel_speed_select_if/Kconfig | 17 +
.../x86/intel_speed_select_if/Makefile | 10 +
.../intel_speed_select_if/isst_if_common.c | 672 +++++++
.../intel_speed_select_if/isst_if_common.h | 69 +
.../intel_speed_select_if/isst_if_mbox_msr.c | 216 +++
.../intel_speed_select_if/isst_if_mbox_pci.c | 214 +++
.../x86/intel_speed_select_if/isst_if_mmio.c | 180 ++
include/uapi/linux/isst_if.h | 172 ++
tools/power/x86/intel_speed_select/Makefile | 31 +
tools/power/x86/intel_speed_select/isst.h | 231 +++
.../x86/intel_speed_select/isst_config.c | 1607 +++++++++++++++++
.../power/x86/intel_speed_select/isst_core.c | 721 ++++++++
.../x86/intel_speed_select/isst_display.c | 479 +++++
16 files changed, 4623 insertions(+)
create mode 100644 drivers/platform/x86/intel_speed_select_if/Kconfig
create mode 100644 drivers/platform/x86/intel_speed_select_if/Makefile
create mode 100644 drivers/platform/x86/intel_speed_select_if/isst_if_common.c
create mode 100644 drivers/platform/x86/intel_speed_select_if/isst_if_common.h
create mode 100644 drivers/platform/x86/intel_speed_select_if/isst_if_mbox_msr.c
create mode 100644 drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c
create mode 100644 drivers/platform/x86/intel_speed_select_if/isst_if_mmio.c
create mode 100644 include/uapi/linux/isst_if.h
create mode 100644 tools/power/x86/intel_speed_select/Makefile
create mode 100644 tools/power/x86/intel_speed_select/isst.h
create mode 100644 tools/power/x86/intel_speed_select/isst_config.c
create mode 100644 tools/power/x86/intel_speed_select/isst_core.c
create mode 100644 tools/power/x86/intel_speed_select/isst_display.c

--
2.17.2

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