| .. 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 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 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 |
