1.. SPDX-License-Identifier: GPL-2.0 2 3============================================================ 4Intel(R) Speed Select Technology User Guide 5============================================================ 6 7The Intel(R) Speed Select Technology (Intel(R) SST) provides a powerful new 8collection of features that give more granular control over CPU performance. 9With Intel(R) SST, one server can be configured for power and performance for a 10variety of diverse workload requirements. 11 12Refer to the links below for an overview of the technology: 13 14- https://www.intel.com/content/www/us/en/architecture-and-technology/speed-select-technology-article.html 15- https://builders.intel.com/docs/networkbuilders/intel-speed-select-technology-base-frequency-enhancing-performance.pdf 16 17These capabilities are further enhanced in some of the newer generations of 18server platforms where these features can be enumerated and controlled 19dynamically without pre-configuring via BIOS setup options. This dynamic 20configuration is done via mailbox commands to the hardware. One way to enumerate 21and configure these features is by using the Intel Speed Select utility. 22 23This document explains how to use the Intel Speed Select tool to enumerate and 24control Intel(R) SST features. This document gives example commands and explains 25how these commands change the power and performance profile of the system under 26test. Using this tool as an example, customers can replicate the messaging 27implemented in the tool in their production software. 28 29intel-speed-select configuration tool 30====================================== 31 32Most Linux distribution packages may include the "intel-speed-select" tool. If not, 33it can be built by downloading the Linux kernel tree from kernel.org. Once 34downloaded, the tool can be built without building the full kernel. 35 36From the kernel tree, run the following commands:: 37 38# cd tools/power/x86/intel-speed-select/ 39# make 40# make install 41 42Getting Help 43------------ 44 45To get help with the tool, execute the command below:: 46 47# intel-speed-select --help 48 49The top-level help describes arguments and features. Notice that there is a 50multi-level help structure in the tool. For example, to get help for the feature "perf-profile":: 51 52# intel-speed-select perf-profile --help 53 54To get help on a command, another level of help is provided. For example for the command info "info":: 55 56# intel-speed-select perf-profile info --help 57 58Summary of platform capability 59------------------------------ 60To check the current platform and driver capabilities, execute:: 61 62#intel-speed-select --info 63 64For example on a test system:: 65 66 # intel-speed-select --info 67 Intel(R) Speed Select Technology 68 Executing on CPU model: X 69 Platform: API version : 1 70 Platform: Driver version : 1 71 Platform: mbox supported : 1 72 Platform: mmio supported : 1 73 Intel(R) SST-PP (feature perf-profile) is supported 74 TDP level change control is unlocked, max level: 4 75 Intel(R) SST-TF (feature turbo-freq) is supported 76 Intel(R) SST-BF (feature base-freq) is not supported 77 Intel(R) SST-CP (feature core-power) is supported 78 79Intel(R) Speed Select Technology - Performance Profile (Intel(R) SST-PP) 80------------------------------------------------------------------------ 81 82This feature allows configuration of a server dynamically based on workload 83performance requirements. This helps users during deployment as they do not have 84to choose a specific server configuration statically. This Intel(R) Speed Select 85Technology - Performance Profile (Intel(R) SST-PP) feature introduces a mechanism 86that allows multiple optimized performance profiles per system. Each profile 87defines a set of CPUs that need to be online and rest offline to sustain a 88guaranteed base frequency. Once the user issues a command to use a specific 89performance profile and meet CPU online/offline requirement, the user can expect 90a change in the base frequency dynamically. This feature is called 91"perf-profile" when using the Intel Speed Select tool. 92 93Number or performance levels 94~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 95 96There can be multiple performance profiles on a system. To get the number of 97profiles, execute the command below:: 98 99 # intel-speed-select perf-profile get-config-levels 100 Intel(R) Speed Select Technology 101 Executing on CPU model: X 102 package-0 103 die-0 104 cpu-0 105 get-config-levels:4 106 package-1 107 die-0 108 cpu-14 109 get-config-levels:4 110 111On this system under test, there are 4 performance profiles in addition to the 112base performance profile (which is performance level 0). 113 114Lock/Unlock status 115~~~~~~~~~~~~~~~~~~ 116 117Even if there are multiple performance profiles, it is possible that they 118are locked. If they are locked, users cannot issue a command to change the 119performance state. It is possible that there is a BIOS setup to unlock or check 120with your system vendor. 121 122To check if the system is locked, execute the following command:: 123 124 # intel-speed-select perf-profile get-lock-status 125 Intel(R) Speed Select Technology 126 Executing on CPU model: X 127 package-0 128 die-0 129 cpu-0 130 get-lock-status:0 131 package-1 132 die-0 133 cpu-14 134 get-lock-status:0 135 136In this case, lock status is 0, which means that the system is unlocked. 137 138Properties of a performance level 139~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 140 141To get properties of a specific performance level (For example for the level 0, below), execute the command below:: 142 143 # intel-speed-select perf-profile info -l 0 144 Intel(R) Speed Select Technology 145 Executing on CPU model: X 146 package-0 147 die-0 148 cpu-0 149 perf-profile-level-0 150 cpu-count:28 151 enable-cpu-mask:000003ff,f0003fff 152 enable-cpu-list:0,1,2,3,4,5,6,7,8,9,10,11,12,13,28,29,30,31,32,33,34,35,36,37,38,39,40,41 153 thermal-design-power-ratio:26 154 base-frequency(MHz):2600 155 speed-select-turbo-freq:disabled 156 speed-select-base-freq:disabled 157 ... 158 ... 159 160Here -l option is used to specify a performance level. 161 162If the option -l is omitted, then this command will print information about all 163the performance levels. The above command is printing properties of the 164performance level 0. 165 166For this performance profile, the list of CPUs displayed by the 167"enable-cpu-mask/enable-cpu-list" at the max can be "online." When that 168condition is met, then base frequency of 2600 MHz can be maintained. To 169understand more, execute "intel-speed-select perf-profile info" for performance 170level 4:: 171 172 # intel-speed-select perf-profile info -l 4 173 Intel(R) Speed Select Technology 174 Executing on CPU model: X 175 package-0 176 die-0 177 cpu-0 178 perf-profile-level-4 179 cpu-count:28 180 enable-cpu-mask:000000fa,f0000faf 181 enable-cpu-list:0,1,2,3,5,7,8,9,10,11,28,29,30,31,33,35,36,37,38,39 182 thermal-design-power-ratio:28 183 base-frequency(MHz):2800 184 speed-select-turbo-freq:disabled 185 speed-select-base-freq:unsupported 186 ... 187 ... 188 189There are fewer CPUs in the "enable-cpu-mask/enable-cpu-list". Consequently, if 190the user only keeps these CPUs online and the rest "offline," then the base 191frequency is increased to 2.8 GHz compared to 2.6 GHz at performance level 0. 192 193Get current performance level 194~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 195 196To get the current performance level, execute:: 197 198 # intel-speed-select perf-profile get-config-current-level 199 Intel(R) Speed Select Technology 200 Executing on CPU model: X 201 package-0 202 die-0 203 cpu-0 204 get-config-current_level:0 205 206First verify that the base_frequency displayed by the cpufreq sysfs is correct:: 207 208 # cat /sys/devices/system/cpu/cpu0/cpufreq/base_frequency 209 2600000 210 211This matches the base-frequency (MHz) field value displayed from the 212"perf-profile info" command for performance level 0(cpufreq frequency is in 213KHz). 214 215To check if the average frequency is equal to the base frequency for a 100% busy 216workload, disable turbo:: 217 218# echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo 219 220Then runs a busy workload on all CPUs, for example:: 221 222#stress -c 64 223 224To verify the base frequency, run turbostat:: 225 226 #turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1 227 228 Package Core CPU Bzy_MHz 229 - - 2600 230 0 0 0 2600 231 0 1 1 2600 232 0 2 2 2600 233 0 3 3 2600 234 0 4 4 2600 235 . . . . 236 237 238Changing performance level 239~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 240 241To the change the performance level to 4, execute:: 242 243 # intel-speed-select -d perf-profile set-config-level -l 4 -o 244 Intel(R) Speed Select Technology 245 Executing on CPU model: X 246 package-0 247 die-0 248 cpu-0 249 perf-profile 250 set_tdp_level:success 251 252In the command above, "-o" is optional. If it is specified, then it will also 253offline CPUs which are not present in the enable_cpu_mask for this performance 254level. 255 256Now if the base_frequency is checked:: 257 258 #cat /sys/devices/system/cpu/cpu0/cpufreq/base_frequency 259 2800000 260 261Which shows that the base frequency now increased from 2600 MHz at performance 262level 0 to 2800 MHz at performance level 4. As a result, any workload, which can 263use fewer CPUs, can see a boost of 200 MHz compared to performance level 0. 264 265Changing performance level via BMC Interface 266~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 267 268It is possible to change SST-PP level using out of band (OOB) agent (Via some 269remote management console, through BMC "Baseboard Management Controller" 270interface). This mode is supported from the Sapphire Rapids processor 271generation. The kernel and tool change to support this mode is added to Linux 272kernel version 5.18. To enable this feature, kernel config 273"CONFIG_INTEL_HFI_THERMAL" is required. The minimum version of the tool 274is "v1.12" to support this feature, which is part of Linux kernel version 5.18. 275 276To support such configuration, this tool can be used as a daemon. Add 277a command line option --oob:: 278 279 # intel-speed-select --oob 280 Intel(R) Speed Select Technology 281 Executing on CPU model:143[0x8f] 282 OOB mode is enabled and will run as daemon 283 284In this mode the tool will online/offline CPUs based on the new performance 285level. 286 287Check presence of other Intel(R) SST features 288--------------------------------------------- 289 290Each of the performance profiles also specifies weather there is support of 291other two Intel(R) SST features (Intel(R) Speed Select Technology - Base Frequency 292(Intel(R) SST-BF) and Intel(R) Speed Select Technology - Turbo Frequency (Intel 293SST-TF)). 294 295For example, from the output of "perf-profile info" above, for level 0 and level 2964: 297 298For level 0:: 299 speed-select-turbo-freq:disabled 300 speed-select-base-freq:disabled 301 302For level 4:: 303 speed-select-turbo-freq:disabled 304 speed-select-base-freq:unsupported 305 306Given these results, the "speed-select-base-freq" (Intel(R) SST-BF) in level 4 307changed from "disabled" to "unsupported" compared to performance level 0. 308 309This means that at performance level 4, the "speed-select-base-freq" feature is 310not supported. However, at performance level 0, this feature is "supported", but 311currently "disabled", meaning the user has not activated this feature. Whereas 312"speed-select-turbo-freq" (Intel(R) SST-TF) is supported at both performance 313levels, but currently not activated by the user. 314 315The Intel(R) SST-BF and the Intel(R) SST-TF features are built on a foundation 316technology called Intel(R) Speed Select Technology - Core Power (Intel(R) SST-CP). 317The platform firmware enables this feature when Intel(R) SST-BF or Intel(R) SST-TF 318is supported on a platform. 319 320Intel(R) Speed Select Technology Core Power (Intel(R) SST-CP) 321--------------------------------------------------------------- 322 323Intel(R) Speed Select Technology Core Power (Intel(R) SST-CP) is an interface that 324allows users to define per core priority. This defines a mechanism to distribute 325power among cores when there is a power constrained scenario. This defines a 326class of service (CLOS) configuration. 327 328The user can configure up to 4 class of service configurations. Each CLOS group 329configuration allows definitions of parameters, which affects how the frequency 330can be limited and power is distributed. Each CPU core can be tied to a class of 331service and hence an associated priority. The granularity is at core level not 332at per CPU level. 333 334Enable CLOS based prioritization 335~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 336 337To use CLOS based prioritization feature, firmware must be informed to enable 338and use a priority type. There is a default per platform priority type, which 339can be changed with optional command line parameter. 340 341To enable and check the options, execute:: 342 343 # intel-speed-select core-power enable --help 344 Intel(R) Speed Select Technology 345 Executing on CPU model: X 346 Enable core-power for a package/die 347 Clos Enable: Specify priority type with [--priority|-p] 348 0: Proportional, 1: Ordered 349 350There are two types of priority types: 351 352- Ordered 353 354Priority for ordered throttling is defined based on the index of the assigned 355CLOS group. Where CLOS0 gets highest priority (throttled last). 356 357Priority order is: 358CLOS0 > CLOS1 > CLOS2 > CLOS3. 359 360- Proportional 361 362When proportional priority is used, there is an additional parameter called 363frequency_weight, which can be specified per CLOS group. The goal of 364proportional priority is to provide each core with the requested min., then 365distribute all remaining (excess/deficit) budgets in proportion to a defined 366weight. This proportional priority can be configured using "core-power config" 367command. 368 369To enable with the platform default priority type, execute:: 370 371 # intel-speed-select core-power enable 372 Intel(R) Speed Select Technology 373 Executing on CPU model: X 374 package-0 375 die-0 376 cpu-0 377 core-power 378 enable:success 379 package-1 380 die-0 381 cpu-6 382 core-power 383 enable:success 384 385The scope of this enable is per package or die scoped when a package contains 386multiple dies. To check if CLOS is enabled and get priority type, "core-power 387info" command can be used. For example to check the status of core-power feature 388on CPU 0, execute:: 389 390 # intel-speed-select -c 0 core-power info 391 Intel(R) Speed Select Technology 392 Executing on CPU model: X 393 package-0 394 die-0 395 cpu-0 396 core-power 397 support-status:supported 398 enable-status:enabled 399 clos-enable-status:enabled 400 priority-type:proportional 401 package-1 402 die-0 403 cpu-24 404 core-power 405 support-status:supported 406 enable-status:enabled 407 clos-enable-status:enabled 408 priority-type:proportional 409 410Configuring CLOS groups 411~~~~~~~~~~~~~~~~~~~~~~~ 412 413Each CLOS group has its own attributes including min, max, freq_weight and 414desired. These parameters can be configured with "core-power config" command. 415Defaults will be used if user skips setting a parameter except clos id, which is 416mandatory. To check core-power config options, execute:: 417 418 # intel-speed-select core-power config --help 419 Intel(R) Speed Select Technology 420 Executing on CPU model: X 421 Set core-power configuration for one of the four clos ids 422 Specify targeted clos id with [--clos|-c] 423 Specify clos Proportional Priority [--weight|-w] 424 Specify clos min in MHz with [--min|-n] 425 Specify clos max in MHz with [--max|-m] 426 427For example:: 428 429 # intel-speed-select core-power config -c 0 430 Intel(R) Speed Select Technology 431 Executing on CPU model: X 432 clos epp is not specified, default: 0 433 clos frequency weight is not specified, default: 0 434 clos min is not specified, default: 0 MHz 435 clos max is not specified, default: 25500 MHz 436 clos desired is not specified, default: 0 437 package-0 438 die-0 439 cpu-0 440 core-power 441 config:success 442 package-1 443 die-0 444 cpu-6 445 core-power 446 config:success 447 448The user has the option to change defaults. For example, the user can change the 449"min" and set the base frequency to always get guaranteed base frequency. 450 451Get the current CLOS configuration 452~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 453 454To check the current configuration, "core-power get-config" can be used. For 455example, to get the configuration of CLOS 0:: 456 457 # intel-speed-select core-power get-config -c 0 458 Intel(R) Speed Select Technology 459 Executing on CPU model: X 460 package-0 461 die-0 462 cpu-0 463 core-power 464 clos:0 465 epp:0 466 clos-proportional-priority:0 467 clos-min:0 MHz 468 clos-max:Max Turbo frequency 469 clos-desired:0 MHz 470 package-1 471 die-0 472 cpu-24 473 core-power 474 clos:0 475 epp:0 476 clos-proportional-priority:0 477 clos-min:0 MHz 478 clos-max:Max Turbo frequency 479 clos-desired:0 MHz 480 481Associating a CPU with a CLOS group 482~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 483 484To associate a CPU to a CLOS group "core-power assoc" command can be used:: 485 486 # intel-speed-select core-power assoc --help 487 Intel(R) Speed Select Technology 488 Executing on CPU model: X 489 Associate a clos id to a CPU 490 Specify targeted clos id with [--clos|-c] 491 492 493For example to associate CPU 10 to CLOS group 3, execute:: 494 495 # intel-speed-select -c 10 core-power assoc -c 3 496 Intel(R) Speed Select Technology 497 Executing on CPU model: X 498 package-0 499 die-0 500 cpu-10 501 core-power 502 assoc:success 503 504Once a CPU is associated, its sibling CPUs are also associated to a CLOS group. 505Once associated, avoid changing Linux "cpufreq" subsystem scaling frequency 506limits. 507 508To check the existing association for a CPU, "core-power get-assoc" command can 509be used. For example, to get association of CPU 10, execute:: 510 511 # intel-speed-select -c 10 core-power get-assoc 512 Intel(R) Speed Select Technology 513 Executing on CPU model: X 514 package-1 515 die-0 516 cpu-10 517 get-assoc 518 clos:3 519 520This shows that CPU 10 is part of a CLOS group 3. 521 522 523Disable CLOS based prioritization 524~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 525 526To disable, execute:: 527 528# intel-speed-select core-power disable 529 530Some features like Intel(R) SST-TF can only be enabled when CLOS based prioritization 531is enabled. For this reason, disabling while Intel(R) SST-TF is enabled can cause 532Intel(R) SST-TF to fail. This will cause the "disable" command to display an error 533if Intel(R) SST-TF is already enabled. In turn, to disable, the Intel(R) SST-TF 534feature must be disabled first. 535 536Intel(R) Speed Select Technology - Base Frequency (Intel(R) SST-BF) 537------------------------------------------------------------------- 538 539The Intel(R) Speed Select Technology - Base Frequency (Intel(R) SST-BF) feature lets 540the user control base frequency. If some critical workload threads demand 541constant high guaranteed performance, then this feature can be used to execute 542the thread at higher base frequency on specific sets of CPUs (high priority 543CPUs) at the cost of lower base frequency (low priority CPUs) on other CPUs. 544This feature does not require offline of the low priority CPUs. 545 546The support of Intel(R) SST-BF depends on the Intel(R) Speed Select Technology - 547Performance Profile (Intel(R) SST-PP) performance level configuration. It is 548possible that only certain performance levels support Intel(R) SST-BF. It is also 549possible that only base performance level (level = 0) has support of Intel 550SST-BF. Consequently, first select the desired performance level to enable this 551feature. 552 553In the system under test here, Intel(R) SST-BF is supported at the base 554performance level 0, but currently disabled. For example for the level 0:: 555 556 # intel-speed-select -c 0 perf-profile info -l 0 557 Intel(R) Speed Select Technology 558 Executing on CPU model: X 559 package-0 560 die-0 561 cpu-0 562 perf-profile-level-0 563 ... 564 565 speed-select-base-freq:disabled 566 ... 567 568Before enabling Intel(R) SST-BF and measuring its impact on a workload 569performance, execute some workload and measure performance and get a baseline 570performance to compare against. 571 572Here the user wants more guaranteed performance. For this reason, it is likely 573that turbo is disabled. To disable turbo, execute:: 574 575#echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo 576 577Based on the output of the "intel-speed-select perf-profile info -l 0" base 578frequency of guaranteed frequency 2600 MHz. 579 580 581Measure baseline performance for comparison 582~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 583 584To compare, pick a multi-threaded workload where each thread can be scheduled on 585separate CPUs. "Hackbench pipe" test is a good example on how to improve 586performance using Intel(R) SST-BF. 587 588Below, the workload is measuring average scheduler wakeup latency, so a lower 589number means better performance:: 590 591 # taskset -c 3,4 perf bench -r 100 sched pipe 592 # Running 'sched/pipe' benchmark: 593 # Executed 1000000 pipe operations between two processes 594 Total time: 6.102 [sec] 595 6.102445 usecs/op 596 163868 ops/sec 597 598While running the above test, if we take turbostat output, it will show us that 5992 of the CPUs are busy and reaching max. frequency (which would be the base 600frequency as the turbo is disabled). The turbostat output:: 601 602 #turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1 603 Package Core CPU Bzy_MHz 604 0 0 0 1000 605 0 1 1 1005 606 0 2 2 1000 607 0 3 3 2600 608 0 4 4 2600 609 0 5 5 1000 610 0 6 6 1000 611 0 7 7 1005 612 0 8 8 1005 613 0 9 9 1000 614 0 10 10 1000 615 0 11 11 995 616 0 12 12 1000 617 0 13 13 1000 618 619From the above turbostat output, both CPU 3 and 4 are very busy and reaching 620full guaranteed frequency of 2600 MHz. 621 622Intel(R) SST-BF Capabilities 623~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 624 625To get capabilities of Intel(R) SST-BF for the current performance level 0, 626execute:: 627 628 # intel-speed-select base-freq info -l 0 629 Intel(R) Speed Select Technology 630 Executing on CPU model: X 631 package-0 632 die-0 633 cpu-0 634 speed-select-base-freq 635 high-priority-base-frequency(MHz):3000 636 high-priority-cpu-mask:00000216,00002160 637 high-priority-cpu-list:5,6,8,13,33,34,36,41 638 low-priority-base-frequency(MHz):2400 639 tjunction-temperature(C):125 640 thermal-design-power(W):205 641 642The above capabilities show that there are some CPUs on this system that can 643offer base frequency of 3000 MHz compared to the standard base frequency at this 644performance levels. Nevertheless, these CPUs are fixed, and they are presented 645via high-priority-cpu-list/high-priority-cpu-mask. But if this Intel(R) SST-BF 646feature is selected, the low priorities CPUs (which are not in 647high-priority-cpu-list) can only offer up to 2400 MHz. As a result, if this 648clipping of low priority CPUs is acceptable, then the user can enable Intel 649SST-BF feature particularly for the above "sched pipe" workload since only two 650CPUs are used, they can be scheduled on high priority CPUs and can get boost of 651400 MHz. 652 653Enable Intel(R) SST-BF 654~~~~~~~~~~~~~~~~~~~~~~ 655 656To enable Intel(R) SST-BF feature, execute:: 657 658 # intel-speed-select base-freq enable -a 659 Intel(R) Speed Select Technology 660 Executing on CPU model: X 661 package-0 662 die-0 663 cpu-0 664 base-freq 665 enable:success 666 package-1 667 die-0 668 cpu-14 669 base-freq 670 enable:success 671 672In this case, -a option is optional. This not only enables Intel(R) SST-BF, but it 673also adjusts the priority of cores using Intel(R) Speed Select Technology Core 674Power (Intel(R) SST-CP) features. This option sets the minimum performance of each 675Intel(R) Speed Select Technology - Performance Profile (Intel(R) SST-PP) class to 676maximum performance so that the hardware will give maximum performance possible 677for each CPU. 678 679If -a option is not used, then the following steps are required before enabling 680Intel(R) SST-BF: 681 682- Discover Intel(R) SST-BF and note low and high priority base frequency 683- Note the high priority CPU list 684- Enable CLOS using core-power feature set 685- Configure CLOS parameters. Use CLOS.min to set to minimum performance 686- Subscribe desired CPUs to CLOS groups 687 688With this configuration, if the same workload is executed by pinning the 689workload to high priority CPUs (CPU 5 and 6 in this case):: 690 691 #taskset -c 5,6 perf bench -r 100 sched pipe 692 # Running 'sched/pipe' benchmark: 693 # Executed 1000000 pipe operations between two processes 694 Total time: 5.627 [sec] 695 5.627922 usecs/op 696 177685 ops/sec 697 698This way, by enabling Intel(R) SST-BF, the performance of this benchmark is 699improved (latency reduced) by 7.79%. From the turbostat output, it can be 700observed that the high priority CPUs reached 3000 MHz compared to 2600 MHz. 701The turbostat output:: 702 703 #turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1 704 Package Core CPU Bzy_MHz 705 0 0 0 2151 706 0 1 1 2166 707 0 2 2 2175 708 0 3 3 2175 709 0 4 4 2175 710 0 5 5 3000 711 0 6 6 3000 712 0 7 7 2180 713 0 8 8 2662 714 0 9 9 2176 715 0 10 10 2175 716 0 11 11 2176 717 0 12 12 2176 718 0 13 13 2661 719 720Disable Intel(R) SST-BF 721~~~~~~~~~~~~~~~~~~~~~~~ 722 723To disable the Intel(R) SST-BF feature, execute:: 724 725# intel-speed-select base-freq disable -a 726 727 728Intel(R) Speed Select Technology - Turbo Frequency (Intel(R) SST-TF) 729-------------------------------------------------------------------- 730 731This feature enables the ability to set different "All core turbo ratio limits" 732to cores based on the priority. By using this feature, some cores can be 733configured to get higher turbo frequency by designating them as high priority at 734the cost of lower or no turbo frequency on the low priority cores. 735 736For this reason, this feature is only useful when system is busy utilizing all 737CPUs, but the user wants some configurable option to get high performance on 738some CPUs. 739 740The support of Intel(R) Speed Select Technology - Turbo Frequency (Intel(R) SST-TF) 741depends on the Intel(R) Speed Select Technology - Performance Profile (Intel 742SST-PP) performance level configuration. It is possible that only a certain 743performance level supports Intel(R) SST-TF. It is also possible that only the base 744performance level (level = 0) has the support of Intel(R) SST-TF. Hence, first 745select the desired performance level to enable this feature. 746 747In the system under test here, Intel(R) SST-TF is supported at the base 748performance level 0, but currently disabled:: 749 750 # intel-speed-select -c 0 perf-profile info -l 0 751 Intel(R) Speed Select Technology 752 package-0 753 die-0 754 cpu-0 755 perf-profile-level-0 756 ... 757 ... 758 speed-select-turbo-freq:disabled 759 ... 760 ... 761 762 763To check if performance can be improved using Intel(R) SST-TF feature, get the turbo 764frequency properties with Intel(R) SST-TF enabled and compare to the base turbo 765capability of this system. 766 767Get Base turbo capability 768~~~~~~~~~~~~~~~~~~~~~~~~~ 769 770To get the base turbo capability of performance level 0, execute:: 771 772 # intel-speed-select perf-profile info -l 0 773 Intel(R) Speed Select Technology 774 Executing on CPU model: X 775 package-0 776 die-0 777 cpu-0 778 perf-profile-level-0 779 ... 780 ... 781 turbo-ratio-limits-sse 782 bucket-0 783 core-count:2 784 max-turbo-frequency(MHz):3200 785 bucket-1 786 core-count:4 787 max-turbo-frequency(MHz):3100 788 bucket-2 789 core-count:6 790 max-turbo-frequency(MHz):3100 791 bucket-3 792 core-count:8 793 max-turbo-frequency(MHz):3100 794 bucket-4 795 core-count:10 796 max-turbo-frequency(MHz):3100 797 bucket-5 798 core-count:12 799 max-turbo-frequency(MHz):3100 800 bucket-6 801 core-count:14 802 max-turbo-frequency(MHz):3100 803 bucket-7 804 core-count:16 805 max-turbo-frequency(MHz):3100 806 807Based on the data above, when all the CPUS are busy, the max. frequency of 3100 808MHz can be achieved. If there is some busy workload on cpu 0 - 11 (e.g. stress) 809and on CPU 12 and 13, execute "hackbench pipe" workload:: 810 811 # taskset -c 12,13 perf bench -r 100 sched pipe 812 # Running 'sched/pipe' benchmark: 813 # Executed 1000000 pipe operations between two processes 814 Total time: 5.705 [sec] 815 5.705488 usecs/op 816 175269 ops/sec 817 818The turbostat output:: 819 820 #turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1 821 Package Core CPU Bzy_MHz 822 0 0 0 3000 823 0 1 1 3000 824 0 2 2 3000 825 0 3 3 3000 826 0 4 4 3000 827 0 5 5 3100 828 0 6 6 3100 829 0 7 7 3000 830 0 8 8 3100 831 0 9 9 3000 832 0 10 10 3000 833 0 11 11 3000 834 0 12 12 3100 835 0 13 13 3100 836 837Based on turbostat output, the performance is limited by frequency cap of 3100 838MHz. To check if the hackbench performance can be improved for CPU 12 and CPU 83913, first check the capability of the Intel(R) SST-TF feature for this performance 840level. 841 842Get Intel(R) SST-TF Capability 843~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 844 845To get the capability, the "turbo-freq info" command can be used:: 846 847 # intel-speed-select turbo-freq info -l 0 848 Intel(R) Speed Select Technology 849 Executing on CPU model: X 850 package-0 851 die-0 852 cpu-0 853 speed-select-turbo-freq 854 bucket-0 855 high-priority-cores-count:2 856 high-priority-max-frequency(MHz):3200 857 high-priority-max-avx2-frequency(MHz):3200 858 high-priority-max-avx512-frequency(MHz):3100 859 bucket-1 860 high-priority-cores-count:4 861 high-priority-max-frequency(MHz):3100 862 high-priority-max-avx2-frequency(MHz):3000 863 high-priority-max-avx512-frequency(MHz):2900 864 bucket-2 865 high-priority-cores-count:6 866 high-priority-max-frequency(MHz):3100 867 high-priority-max-avx2-frequency(MHz):3000 868 high-priority-max-avx512-frequency(MHz):2900 869 speed-select-turbo-freq-clip-frequencies 870 low-priority-max-frequency(MHz):2600 871 low-priority-max-avx2-frequency(MHz):2400 872 low-priority-max-avx512-frequency(MHz):2100 873 874Based on the output above, there is an Intel(R) SST-TF bucket for which there are 875two high priority cores. If only two high priority cores are set, then max. 876turbo frequency on those cores can be increased to 3200 MHz. This is 100 MHz 877more than the base turbo capability for all cores. 878 879In turn, for the hackbench workload, two CPUs can be set as high priority and 880rest as low priority. One side effect is that once enabled, the low priority 881cores will be clipped to a lower frequency of 2600 MHz. 882 883Enable Intel(R) SST-TF 884~~~~~~~~~~~~~~~~~~~~~~ 885 886To enable Intel(R) SST-TF, execute:: 887 888 # intel-speed-select -c 12,13 turbo-freq enable -a 889 Intel(R) Speed Select Technology 890 Executing on CPU model: X 891 package-0 892 die-0 893 cpu-12 894 turbo-freq 895 enable:success 896 package-0 897 die-0 898 cpu-13 899 turbo-freq 900 enable:success 901 package--1 902 die-0 903 cpu-63 904 turbo-freq --auto 905 enable:success 906 907In this case, the option "-a" is optional. If set, it enables Intel(R) SST-TF 908feature and also sets the CPUs to high and low priority using Intel Speed 909Select Technology Core Power (Intel(R) SST-CP) features. The CPU numbers passed 910with "-c" arguments are marked as high priority, including its siblings. 911 912If -a option is not used, then the following steps are required before enabling 913Intel(R) SST-TF: 914 915- Discover Intel(R) SST-TF and note buckets of high priority cores and maximum frequency 916 917- Enable CLOS using core-power feature set - Configure CLOS parameters 918 919- Subscribe desired CPUs to CLOS groups making sure that high priority cores are set to the maximum frequency 920 921If the same hackbench workload is executed, schedule hackbench threads on high 922priority CPUs:: 923 924 #taskset -c 12,13 perf bench -r 100 sched pipe 925 # Running 'sched/pipe' benchmark: 926 # Executed 1000000 pipe operations between two processes 927 Total time: 5.510 [sec] 928 5.510165 usecs/op 929 180826 ops/sec 930 931This improved performance by around 3.3% improvement on a busy system. Here the 932turbostat output will show that the CPU 12 and CPU 13 are getting 100 MHz boost. 933The turbostat output:: 934 935 #turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1 936 Package Core CPU Bzy_MHz 937 ... 938 0 12 12 3200 939 0 13 13 3200 940