mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-18 01:34:14 +08:00
213081dadd
Added documentation to configure servers to use Intel(R) Speed Select Technology using intel-speed-select tool. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Acked-by: Andriy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
918 lines
30 KiB
ReStructuredText
918 lines
30 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
============================================================
|
|
Intel(R) Speed Select Technology User Guide
|
|
============================================================
|
|
|
|
The Intel(R) Speed Select Technology (Intel(R) SST) provides a powerful new
|
|
collection of features that give more granular control over CPU performance.
|
|
With Intel(R) SST, one server can be configured for power and performance for a
|
|
variety of diverse workload requirements.
|
|
|
|
Refer to the links below for an overview of the technology:
|
|
|
|
- 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
|
|
|
|
These capabilities are further enhanced in some of the newer generations of
|
|
server platforms where these features can be enumerated and controlled
|
|
dynamically without pre-configuring via BIOS setup options. This dynamic
|
|
configuration is done via mailbox commands to the hardware. One way to enumerate
|
|
and configure these features is by using the Intel Speed Select utility.
|
|
|
|
This document explains how to use the Intel Speed Select tool to enumerate and
|
|
control Intel(R) SST features. This document gives example commands and explains
|
|
how these commands change the power and performance profile of the system under
|
|
test. Using this tool as an example, customers can replicate the messaging
|
|
implemented in the tool in their production software.
|
|
|
|
intel-speed-select configuration tool
|
|
======================================
|
|
|
|
Most Linux distribution packages may include the "intel-speed-select" tool. If not,
|
|
it can be built by downloading the Linux kernel tree from kernel.org. Once
|
|
downloaded, the tool can be built without building the full kernel.
|
|
|
|
From the kernel tree, run the following commands::
|
|
|
|
# cd tools/power/x86/intel-speed-select/
|
|
# make
|
|
# make install
|
|
|
|
Getting Help
|
|
------------
|
|
|
|
To get help with the tool, execute the command below::
|
|
|
|
# intel-speed-select --help
|
|
|
|
The top-level help describes arguments and features. Notice that there is a
|
|
multi-level help structure in the tool. For example, to get help for the feature "perf-profile"::
|
|
|
|
# intel-speed-select perf-profile --help
|
|
|
|
To get help on a command, another level of help is provided. For example for the command info "info"::
|
|
|
|
# intel-speed-select perf-profile info --help
|
|
|
|
Summary of platform capability
|
|
------------------------------
|
|
To check the current platform and driver capaibilities, execute::
|
|
|
|
#intel-speed-select --info
|
|
|
|
For example on a test system::
|
|
|
|
# intel-speed-select --info
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
Platform: API version : 1
|
|
Platform: Driver version : 1
|
|
Platform: mbox supported : 1
|
|
Platform: mmio supported : 1
|
|
Intel(R) SST-PP (feature perf-profile) is supported
|
|
TDP level change control is unlocked, max level: 4
|
|
Intel(R) SST-TF (feature turbo-freq) is supported
|
|
Intel(R) SST-BF (feature base-freq) is not supported
|
|
Intel(R) SST-CP (feature core-power) is supported
|
|
|
|
Intel(R) Speed Select Technology - Performance Profile (Intel(R) SST-PP)
|
|
------------------------------------------------------------------------
|
|
|
|
This feature allows configuration of a server dynamically based on workload
|
|
performance requirements. This helps users during deployment as they do not have
|
|
to choose a specific server configuration statically. This Intel(R) Speed Select
|
|
Technology - Performance Profile (Intel(R) SST-PP) feature introduces a mechanism
|
|
that allows multiple optimized performance profiles per system. Each profile
|
|
defines a set of CPUs that need to be online and rest offline to sustain a
|
|
guaranteed base frequency. Once the user issues a command to use a specific
|
|
performance profile and meet CPU online/offline requirement, the user can expect
|
|
a change in the base frequency dynamically. This feature is called
|
|
"perf-profile" when using the Intel Speed Select tool.
|
|
|
|
Number or performance levels
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
There can be multiple performance profiles on a system. To get the number of
|
|
profiles, execute the command below::
|
|
|
|
# intel-speed-select perf-profile get-config-levels
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
get-config-levels:4
|
|
package-1
|
|
die-0
|
|
cpu-14
|
|
get-config-levels:4
|
|
|
|
On this system under test, there are 4 performance profiles in addition to the
|
|
base performance profile (which is performance level 0).
|
|
|
|
Lock/Unlock status
|
|
~~~~~~~~~~~~~~~~~~
|
|
|
|
Even if there are multiple performance profiles, it is possible that that they
|
|
are locked. If they are locked, users cannot issue a command to change the
|
|
performance state. It is possible that there is a BIOS setup to unlock or check
|
|
with your system vendor.
|
|
|
|
To check if the system is locked, execute the following command::
|
|
|
|
# intel-speed-select perf-profile get-lock-status
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
get-lock-status:0
|
|
package-1
|
|
die-0
|
|
cpu-14
|
|
get-lock-status:0
|
|
|
|
In this case, lock status is 0, which means that the system is unlocked.
|
|
|
|
Properties of a performance level
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To get properties of a specific performance level (For example for the level 0, below), execute the command below::
|
|
|
|
# intel-speed-select perf-profile info -l 0
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
perf-profile-level-0
|
|
cpu-count:28
|
|
enable-cpu-mask:000003ff,f0003fff
|
|
enable-cpu-list:0,1,2,3,4,5,6,7,8,9,10,11,12,13,28,29,30,31,32,33,34,35,36,37,38,39,40,41
|
|
thermal-design-power-ratio:26
|
|
base-frequency(MHz):2600
|
|
speed-select-turbo-freq:disabled
|
|
speed-select-base-freq:disabled
|
|
...
|
|
...
|
|
|
|
Here -l option is used to specify a performance level.
|
|
|
|
If the option -l is omitted, then this command will print information about all
|
|
the performance levels. The above command is printing properties of the
|
|
performance level 0.
|
|
|
|
For this performance profile, the list of CPUs displayed by the
|
|
"enable-cpu-mask/enable-cpu-list" at the max can be "online." When that
|
|
condition is met, then base frequency of 2600 MHz can be maintained. To
|
|
understand more, execute "intel-speed-select perf-profile info" for performance
|
|
level 4::
|
|
|
|
# intel-speed-select perf-profile info -l 4
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
perf-profile-level-4
|
|
cpu-count:28
|
|
enable-cpu-mask:000000fa,f0000faf
|
|
enable-cpu-list:0,1,2,3,5,7,8,9,10,11,28,29,30,31,33,35,36,37,38,39
|
|
thermal-design-power-ratio:28
|
|
base-frequency(MHz):2800
|
|
speed-select-turbo-freq:disabled
|
|
speed-select-base-freq:unsupported
|
|
...
|
|
...
|
|
|
|
There are fewer CPUs in the "enable-cpu-mask/enable-cpu-list". Consequently, if
|
|
the user only keeps these CPUs online and the rest "offline," then the base
|
|
frequency is increased to 2.8 GHz compared to 2.6 GHz at performance level 0.
|
|
|
|
Get current performance level
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To get the current performance level, execute::
|
|
|
|
# intel-speed-select perf-profile get-config-current-level
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
get-config-current_level:0
|
|
|
|
First verify that the base_frequency displayed by the cpufreq sysfs is correct::
|
|
|
|
# cat /sys/devices/system/cpu/cpu0/cpufreq/base_frequency
|
|
2600000
|
|
|
|
This matches the base-frequency (MHz) field value displayed from the
|
|
"perf-profile info" command for performance level 0(cpufreq frequency is in
|
|
KHz).
|
|
|
|
To check if the average frequency is equal to the base frequency for a 100% busy
|
|
workload, disable turbo::
|
|
|
|
# echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo
|
|
|
|
Then runs a busy workload on all CPUs, for example::
|
|
|
|
#stress -c 64
|
|
|
|
To verify the base frequency, run turbostat::
|
|
|
|
#turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1
|
|
|
|
Package Core CPU Bzy_MHz
|
|
- - 2600
|
|
0 0 0 2600
|
|
0 1 1 2600
|
|
0 2 2 2600
|
|
0 3 3 2600
|
|
0 4 4 2600
|
|
. . . .
|
|
|
|
|
|
Changing performance level
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To the change the performance level to 4, execute::
|
|
|
|
# intel-speed-select -d perf-profile set-config-level -l 4 -o
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
perf-profile
|
|
set_tdp_level:success
|
|
|
|
In the command above, "-o" is optional. If it is specified, then it will also
|
|
offline CPUs which are not present in the enable_cpu_mask for this performance
|
|
level.
|
|
|
|
Now if the base_frequency is checked::
|
|
|
|
#cat /sys/devices/system/cpu/cpu0/cpufreq/base_frequency
|
|
2800000
|
|
|
|
Which shows that the base frequency now increased from 2600 MHz at performance
|
|
level 0 to 2800 MHz at performance level 4. As a result, any workload, which can
|
|
use fewer CPUs, can see a boost of 200 MHz compared to performance level 0.
|
|
|
|
Check presence of other Intel(R) SST features
|
|
---------------------------------------------
|
|
|
|
Each of the performance profiles also specifies weather there is support of
|
|
other two Intel(R) SST features (Intel(R) Speed Select Technology - Base Frequency
|
|
(Intel(R) SST-BF) and Intel(R) Speed Select Technology - Turbo Frequency (Intel
|
|
SST-TF)).
|
|
|
|
For example, from the output of "perf-profile info" above, for level 0 and level
|
|
4:
|
|
|
|
For level 0::
|
|
speed-select-turbo-freq:disabled
|
|
speed-select-base-freq:disabled
|
|
|
|
For level 4::
|
|
speed-select-turbo-freq:disabled
|
|
speed-select-base-freq:unsupported
|
|
|
|
Given these results, the "speed-select-base-freq" (Intel(R) SST-BF) in level 4
|
|
changed from "disabled" to "unsupported" compared to performance level 0.
|
|
|
|
This means that at performance level 4, the "speed-select-base-freq" feature is
|
|
not supported. However, at performance level 0, this feature is "supported", but
|
|
currently "disabled", meaning the user has not activated this feature. Whereas
|
|
"speed-select-turbo-freq" (Intel(R) SST-TF) is supported at both performance
|
|
levels, but currently not activated by the user.
|
|
|
|
The Intel(R) SST-BF and the Intel(R) SST-TF features are built on a foundation
|
|
technology called Intel(R) Speed Select Technology - Core Power (Intel(R) SST-CP).
|
|
The platform firmware enables this feature when Intel(R) SST-BF or Intel(R) SST-TF
|
|
is supported on a platform.
|
|
|
|
Intel(R) Speed Select Technology Core Power (Intel(R) SST-CP)
|
|
---------------------------------------------------------------
|
|
|
|
Intel(R) Speed Select Technology Core Power (Intel(R) SST-CP) is an interface that
|
|
allows users 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 (CLOS) configuration.
|
|
|
|
The user can configure up to 4 class of service configurations. Each CLOS group
|
|
configuration allows definitions of parameters, which affects how the frequency
|
|
can be limited and power is distributed. Each CPU core can be tied to a class of
|
|
service and hence an associated priority. The granularity is at core level not
|
|
at per CPU level.
|
|
|
|
Enable CLOS based prioritization
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To use CLOS based prioritization feature, firmware must be informed to enable
|
|
and use a priority type. There is a default per platform priority type, which
|
|
can be changed with optional command line parameter.
|
|
|
|
To enable and check the options, execute::
|
|
|
|
# intel-speed-select core-power enable --help
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
Enable core-power for a package/die
|
|
Clos Enable: Specify priority type with [--priority|-p]
|
|
0: Proportional, 1: Ordered
|
|
|
|
There are two types of priority types:
|
|
|
|
- Ordered
|
|
|
|
Priority for ordered throttling is defined based on the index of the assigned
|
|
CLOS group. Where CLOS0 gets highest priority (throttled last).
|
|
|
|
Priority order is:
|
|
CLOS0 > CLOS1 > CLOS2 > CLOS3.
|
|
|
|
- Proportional
|
|
|
|
When proportional priority is used, there is an additional parameter called
|
|
frequency_weight, which can be specified per CLOS group. The goal of
|
|
proportional priority is to provide each core with the requested min., then
|
|
distribute all remaining (excess/deficit) budgets in proportion to a defined
|
|
weight. This proportional priority can be configured using "core-power config"
|
|
command.
|
|
|
|
To enable with the platform default priority type, execute::
|
|
|
|
# intel-speed-select core-power enable
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
core-power
|
|
enable:success
|
|
package-1
|
|
die-0
|
|
cpu-6
|
|
core-power
|
|
enable:success
|
|
|
|
The scope of this enable is per package or die scoped when a package contains
|
|
multiple dies. To check if CLOS is enabled and get priority type, "core-power
|
|
info" command can be used. For example to check the status of core-power feature
|
|
on CPU 0, execute::
|
|
|
|
# intel-speed-select -c 0 core-power info
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
core-power
|
|
support-status:supported
|
|
enable-status:enabled
|
|
clos-enable-status:enabled
|
|
priority-type:proportional
|
|
package-1
|
|
die-0
|
|
cpu-24
|
|
core-power
|
|
support-status:supported
|
|
enable-status:enabled
|
|
clos-enable-status:enabled
|
|
priority-type:proportional
|
|
|
|
Configuring CLOS groups
|
|
~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Each CLOS group has its own attributes including min, max, freq_weight and
|
|
desired. These parameters can be configured with "core-power config" command.
|
|
Defaults will be used if user skips setting a parameter except clos id, which is
|
|
mandatory. To check core-power config options, execute::
|
|
|
|
# intel-speed-select core-power config --help
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
Set core-power configuration for one of the four clos ids
|
|
Specify targeted clos id with [--clos|-c]
|
|
Specify clos Proportional Priority [--weight|-w]
|
|
Specify clos min in MHz with [--min|-n]
|
|
Specify clos max in MHz with [--max|-m]
|
|
|
|
For example::
|
|
|
|
# intel-speed-select core-power config -c 0
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
clos epp is not specified, default: 0
|
|
clos frequency weight is not specified, default: 0
|
|
clos min is not specified, default: 0 MHz
|
|
clos max is not specified, default: 25500 MHz
|
|
clos desired is not specified, default: 0
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
core-power
|
|
config:success
|
|
package-1
|
|
die-0
|
|
cpu-6
|
|
core-power
|
|
config:success
|
|
|
|
The user has the option to change defaults. For example, the user can change the
|
|
"min" and set the base frequency to always get guaranteed base frequency.
|
|
|
|
Get the current CLOS configuration
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To check the current configuration, "core-power get-config" can be used. For
|
|
example, to get the configuration of CLOS 0::
|
|
|
|
# intel-speed-select core-power get-config -c 0
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
core-power
|
|
clos:0
|
|
epp:0
|
|
clos-proportional-priority:0
|
|
clos-min:0 MHz
|
|
clos-max:Max Turbo frequency
|
|
clos-desired:0 MHz
|
|
package-1
|
|
die-0
|
|
cpu-24
|
|
core-power
|
|
clos:0
|
|
epp:0
|
|
clos-proportional-priority:0
|
|
clos-min:0 MHz
|
|
clos-max:Max Turbo frequency
|
|
clos-desired:0 MHz
|
|
|
|
Associating a CPU with a CLOS group
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To associate a CPU to a CLOS group "core-power assoc" command can be used::
|
|
|
|
# intel-speed-select core-power assoc --help
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
Associate a clos id to a CPU
|
|
Specify targeted clos id with [--clos|-c]
|
|
|
|
|
|
For example to associate CPU 10 to CLOS group 3, execute::
|
|
|
|
# intel-speed-select -c 10 core-power assoc -c 3
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-10
|
|
core-power
|
|
assoc:success
|
|
|
|
Once a CPU is associated, its sibling CPUs are also associated to a CLOS group.
|
|
Once associated, avoid changing Linux "cpufreq" subsystem scaling frequency
|
|
limits.
|
|
|
|
To check the existing association for a CPU, "core-power get-assoc" command can
|
|
be used. For example, to get association of CPU 10, execute::
|
|
|
|
# intel-speed-select -c 10 core-power get-assoc
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-1
|
|
die-0
|
|
cpu-10
|
|
get-assoc
|
|
clos:3
|
|
|
|
This shows that CPU 10 is part of a CLOS group 3.
|
|
|
|
|
|
Disable CLOS based prioritization
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To disable, execute::
|
|
|
|
# intel-speed-select core-power disable
|
|
|
|
Some features like Intel(R) SST-TF can only be enabled when CLOS based prioritization
|
|
is enabled. For this reason, disabling while Intel(R) SST-TF is enabled can cause
|
|
Intel(R) SST-TF to fail. This will cause the "disable" command to display an error
|
|
if Intel(R) SST-TF is already enabled. In turn, to disable, the Intel(R) SST-TF
|
|
feature must be disabled first.
|
|
|
|
Intel(R) Speed Select Technology - Base Frequency (Intel(R) SST-BF)
|
|
-------------------------------------------------------------------
|
|
|
|
The Intel(R) Speed Select Technology - Base Frequency (Intel(R) SST-BF) feature lets
|
|
the user control 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 sets of CPUs (high priority
|
|
CPUs) at the cost of lower base frequency (low priority CPUs) on other CPUs.
|
|
This feature does not require offline of the low priority CPUs.
|
|
|
|
The support of Intel(R) SST-BF depends on the Intel(R) Speed Select Technology -
|
|
Performance Profile (Intel(R) SST-PP) performance level configuration. It is
|
|
possible that only certain performance levels support Intel(R) SST-BF. It is also
|
|
possible that only base performance level (level = 0) has support of Intel
|
|
SST-BF. Consequently, first select the desired performance level to enable this
|
|
feature.
|
|
|
|
In the system under test here, Intel(R) SST-BF is supported at the base
|
|
performance level 0, but currently disabled. For example for the level 0::
|
|
|
|
# intel-speed-select -c 0 perf-profile info -l 0
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
perf-profile-level-0
|
|
...
|
|
|
|
speed-select-base-freq:disabled
|
|
...
|
|
|
|
Before enabling Intel(R) SST-BF and measuring its impact on a workload
|
|
performance, execute some workload and measure performance and get a baseline
|
|
performance to compare against.
|
|
|
|
Here the user wants more guaranteed performance. For this reason, it is likely
|
|
that turbo is disabled. To disable turbo, execute::
|
|
|
|
#echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo
|
|
|
|
Based on the output of the "intel-speed-select perf-profile info -l 0" base
|
|
frequency of guaranteed frequency 2600 MHz.
|
|
|
|
|
|
Measure baseline performance for comparison
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To compare, pick a multi-threaded workload where each thread can be scheduled on
|
|
separate CPUs. "Hackbench pipe" test is a good example on how to improve
|
|
performance using Intel(R) SST-BF.
|
|
|
|
Below, the workload is measuring average scheduler wakeup latency, so a lower
|
|
number means better performance::
|
|
|
|
# taskset -c 3,4 perf bench -r 100 sched pipe
|
|
# Running 'sched/pipe' benchmark:
|
|
# Executed 1000000 pipe operations between two processes
|
|
Total time: 6.102 [sec]
|
|
6.102445 usecs/op
|
|
163868 ops/sec
|
|
|
|
While running the above test, if we take turbostat output, it will show us that
|
|
2 of the CPUs are busy and reaching max. frequency (which would be the base
|
|
frequency as the turbo is disabled). The turbostat output::
|
|
|
|
#turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1
|
|
Package Core CPU Bzy_MHz
|
|
0 0 0 1000
|
|
0 1 1 1005
|
|
0 2 2 1000
|
|
0 3 3 2600
|
|
0 4 4 2600
|
|
0 5 5 1000
|
|
0 6 6 1000
|
|
0 7 7 1005
|
|
0 8 8 1005
|
|
0 9 9 1000
|
|
0 10 10 1000
|
|
0 11 11 995
|
|
0 12 12 1000
|
|
0 13 13 1000
|
|
|
|
From the above turbostat output, both CPU 3 and 4 are very busy and reaching
|
|
full guaranteed frequency of 2600 MHz.
|
|
|
|
Intel(R) SST-BF Capabilities
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To get capabilities of Intel(R) SST-BF for the current performance level 0,
|
|
execute::
|
|
|
|
# intel-speed-select base-freq info -l 0
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
speed-select-base-freq
|
|
high-priority-base-frequency(MHz):3000
|
|
high-priority-cpu-mask:00000216,00002160
|
|
high-priority-cpu-list:5,6,8,13,33,34,36,41
|
|
low-priority-base-frequency(MHz):2400
|
|
tjunction-temperature(C):125
|
|
thermal-design-power(W):205
|
|
|
|
The above capabilities show that there are some CPUs on this system that can
|
|
offer base frequency of 3000 MHz compared to the standard base frequency at this
|
|
performance levels. Nevertheless, these CPUs are fixed, and they are presented
|
|
via high-priority-cpu-list/high-priority-cpu-mask. But if this Intel(R) SST-BF
|
|
feature is selected, the low priorities CPUs (which are not in
|
|
high-priority-cpu-list) can only offer up to 2400 MHz. As a result, if this
|
|
clipping of low priority CPUs is acceptable, then the user can enable Intel
|
|
SST-BF feature particularly for the above "sched pipe" workload since only two
|
|
CPUs are used, they can be scheduled on high priority CPUs and can get boost of
|
|
400 MHz.
|
|
|
|
Enable Intel(R) SST-BF
|
|
~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To enable Intel(R) SST-BF feature, execute::
|
|
|
|
# intel-speed-select base-freq enable -a
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
base-freq
|
|
enable:success
|
|
package-1
|
|
die-0
|
|
cpu-14
|
|
base-freq
|
|
enable:success
|
|
|
|
In this case, -a option is optional. This not only enables Intel(R) SST-BF, but it
|
|
also adjusts the priority of cores using Intel(R) Speed Select Technology Core
|
|
Power (Intel(R) SST-CP) features. This option sets the minimum performance of each
|
|
Intel(R) Speed Select Technology - Performance Profile (Intel(R) SST-PP) class to
|
|
maximum performance so that the hardware will give maximum performance possible
|
|
for each CPU.
|
|
|
|
If -a option is not used, then the following steps are required before enabling
|
|
Intel(R) SST-BF:
|
|
|
|
- Discover Intel(R) SST-BF and note low and high priority base frequency
|
|
- Note the high prioity CPU list
|
|
- Enable CLOS using core-power feature set
|
|
- Configure CLOS parameters. Use CLOS.min to set to minimum performance
|
|
- Subscribe desired CPUs to CLOS groups
|
|
|
|
With this configuration, if the same workload is executed by pinning the
|
|
workload to high priority CPUs (CPU 5 and 6 in this case)::
|
|
|
|
#taskset -c 5,6 perf bench -r 100 sched pipe
|
|
# Running 'sched/pipe' benchmark:
|
|
# Executed 1000000 pipe operations between two processes
|
|
Total time: 5.627 [sec]
|
|
5.627922 usecs/op
|
|
177685 ops/sec
|
|
|
|
This way, by enabling Intel(R) SST-BF, the performance of this benchmark is
|
|
improved (latency reduced) by 7.79%. From the turbostat output, it can be
|
|
observed that the high priority CPUs reached 3000 MHz compared to 2600 MHz.
|
|
The turbostat output::
|
|
|
|
#turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1
|
|
Package Core CPU Bzy_MHz
|
|
0 0 0 2151
|
|
0 1 1 2166
|
|
0 2 2 2175
|
|
0 3 3 2175
|
|
0 4 4 2175
|
|
0 5 5 3000
|
|
0 6 6 3000
|
|
0 7 7 2180
|
|
0 8 8 2662
|
|
0 9 9 2176
|
|
0 10 10 2175
|
|
0 11 11 2176
|
|
0 12 12 2176
|
|
0 13 13 2661
|
|
|
|
Disable Intel(R) SST-BF
|
|
~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To disable the Intel(R) SST-BF feature, execute::
|
|
|
|
# intel-speed-select base-freq disable -a
|
|
|
|
|
|
Intel(R) Speed Select Technology - Turbo Frequency (Intel(R) SST-TF)
|
|
--------------------------------------------------------------------
|
|
|
|
This feature enables the ability to set different "All core turbo ratio limits"
|
|
to cores based on the priority. By using this feature, 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.
|
|
|
|
For this reason, this feature is only useful when system is busy utilizing all
|
|
CPUs, but the user wants some configurable option to get high performance on
|
|
some CPUs.
|
|
|
|
The support of Intel(R) Speed Select Technology - Turbo Frequency (Intel(R) SST-TF)
|
|
depends on the Intel(R) Speed Select Technology - Performance Profile (Intel
|
|
SST-PP) performance level configuration. It is possible that only a certain
|
|
performance level supports Intel(R) SST-TF. It is also possible that only the base
|
|
performance level (level = 0) has the support of Intel(R) SST-TF. Hence, first
|
|
select the desired performance level to enable this feature.
|
|
|
|
In the system under test here, Intel(R) SST-TF is supported at the base
|
|
performance level 0, but currently disabled::
|
|
|
|
# intel-speed-select -c 0 perf-profile info -l 0
|
|
Intel(R) Speed Select Technology
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
perf-profile-level-0
|
|
...
|
|
...
|
|
speed-select-turbo-freq:disabled
|
|
...
|
|
...
|
|
|
|
|
|
To check if performance can be improved using Intel(R) SST-TF feature, get the turbo
|
|
frequency properties with Intel(R) SST-TF enabled and compare to the base turbo
|
|
capability of this system.
|
|
|
|
Get Base turbo capability
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To get the base turbo capability of performance level 0, execute::
|
|
|
|
# intel-speed-select perf-profile info -l 0
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
perf-profile-level-0
|
|
...
|
|
...
|
|
turbo-ratio-limits-sse
|
|
bucket-0
|
|
core-count:2
|
|
max-turbo-frequency(MHz):3200
|
|
bucket-1
|
|
core-count:4
|
|
max-turbo-frequency(MHz):3100
|
|
bucket-2
|
|
core-count:6
|
|
max-turbo-frequency(MHz):3100
|
|
bucket-3
|
|
core-count:8
|
|
max-turbo-frequency(MHz):3100
|
|
bucket-4
|
|
core-count:10
|
|
max-turbo-frequency(MHz):3100
|
|
bucket-5
|
|
core-count:12
|
|
max-turbo-frequency(MHz):3100
|
|
bucket-6
|
|
core-count:14
|
|
max-turbo-frequency(MHz):3100
|
|
bucket-7
|
|
core-count:16
|
|
max-turbo-frequency(MHz):3100
|
|
|
|
Based on the data above, when all the CPUS are busy, the max. frequency of 3100
|
|
MHz can be achieved. If there is some busy workload on cpu 0 - 11 (e.g. stress)
|
|
and on CPU 12 and 13, execute "hackbench pipe" workload::
|
|
|
|
# taskset -c 12,13 perf bench -r 100 sched pipe
|
|
# Running 'sched/pipe' benchmark:
|
|
# Executed 1000000 pipe operations between two processes
|
|
Total time: 5.705 [sec]
|
|
5.705488 usecs/op
|
|
175269 ops/sec
|
|
|
|
The turbostat output::
|
|
|
|
#turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1
|
|
Package Core CPU Bzy_MHz
|
|
0 0 0 3000
|
|
0 1 1 3000
|
|
0 2 2 3000
|
|
0 3 3 3000
|
|
0 4 4 3000
|
|
0 5 5 3100
|
|
0 6 6 3100
|
|
0 7 7 3000
|
|
0 8 8 3100
|
|
0 9 9 3000
|
|
0 10 10 3000
|
|
0 11 11 3000
|
|
0 12 12 3100
|
|
0 13 13 3100
|
|
|
|
Based on turbostat output, the performance is limited by frequency cap of 3100
|
|
MHz. To check if the hackbench performance can be improved for CPU 12 and CPU
|
|
13, first check the capability of the Intel(R) SST-TF feature for this performance
|
|
level.
|
|
|
|
Get Intel(R) SST-TF Capability
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To get the capability, the "turbo-freq info" command can be used::
|
|
|
|
# intel-speed-select turbo-freq info -l 0
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-0
|
|
speed-select-turbo-freq
|
|
bucket-0
|
|
high-priority-cores-count:2
|
|
high-priority-max-frequency(MHz):3200
|
|
high-priority-max-avx2-frequency(MHz):3200
|
|
high-priority-max-avx512-frequency(MHz):3100
|
|
bucket-1
|
|
high-priority-cores-count:4
|
|
high-priority-max-frequency(MHz):3100
|
|
high-priority-max-avx2-frequency(MHz):3000
|
|
high-priority-max-avx512-frequency(MHz):2900
|
|
bucket-2
|
|
high-priority-cores-count:6
|
|
high-priority-max-frequency(MHz):3100
|
|
high-priority-max-avx2-frequency(MHz):3000
|
|
high-priority-max-avx512-frequency(MHz):2900
|
|
speed-select-turbo-freq-clip-frequencies
|
|
low-priority-max-frequency(MHz):2600
|
|
low-priority-max-avx2-frequency(MHz):2400
|
|
low-priority-max-avx512-frequency(MHz):2100
|
|
|
|
Based on the output above, there is an Intel(R) SST-TF bucket for which there are
|
|
two high priority cores. If only two high priority cores are set, then max.
|
|
turbo frequency on those cores can be increased to 3200 MHz. This is 100 MHz
|
|
more than the base turbo capability for all cores.
|
|
|
|
In turn, for the hackbench workload, two CPUs can be set as high priority and
|
|
rest as low priority. One side effect is that once enabled, the low priority
|
|
cores will be clipped to a lower frequency of 2600 MHz.
|
|
|
|
Enable Intel(R) SST-TF
|
|
~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
To enable Intel(R) SST-TF, execute::
|
|
|
|
# intel-speed-select -c 12,13 turbo-freq enable -a
|
|
Intel(R) Speed Select Technology
|
|
Executing on CPU model: X
|
|
package-0
|
|
die-0
|
|
cpu-12
|
|
turbo-freq
|
|
enable:success
|
|
package-0
|
|
die-0
|
|
cpu-13
|
|
turbo-freq
|
|
enable:success
|
|
package--1
|
|
die-0
|
|
cpu-63
|
|
turbo-freq --auto
|
|
enable:success
|
|
|
|
In this case, the option "-a" is optional. If set, it enables Intel(R) SST-TF
|
|
feature and also sets the CPUs to high and and low priority using Intel Speed
|
|
Select Technology Core Power (Intel(R) SST-CP) features. The CPU numbers passed
|
|
with "-c" arguments are marked as high priority, including its siblings.
|
|
|
|
If -a option is not used, then the following steps are required before enabling
|
|
Intel(R) SST-TF:
|
|
|
|
- Discover Intel(R) SST-TF and note buckets of high priority cores and maximum frequency
|
|
|
|
- Enable CLOS using core-power feature set - Configure CLOS parameters
|
|
|
|
- Subscribe desired CPUs to CLOS groups making sure that high priority cores are set to the maximum frequency
|
|
|
|
If the same hackbench workload is executed, schedule hackbench threads on high
|
|
priority CPUs::
|
|
|
|
#taskset -c 12,13 perf bench -r 100 sched pipe
|
|
# Running 'sched/pipe' benchmark:
|
|
# Executed 1000000 pipe operations between two processes
|
|
Total time: 5.510 [sec]
|
|
5.510165 usecs/op
|
|
180826 ops/sec
|
|
|
|
This improved performance by around 3.3% improvement on a busy system. Here the
|
|
turbostat output will show that the CPU 12 and CPU 13 are getting 100 MHz boost.
|
|
The turbostat output::
|
|
|
|
#turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1
|
|
Package Core CPU Bzy_MHz
|
|
...
|
|
0 12 12 3200
|
|
0 13 13 3200
|