{ "content": [ { "type": "text", "text": "# uclampset(1) (man)\n\n**Summary:** uclampset - manipulate the utilization clamping attributes of the system or a process\n\n**Synopsis:** uclampset [options] [-m uclampmin] [-M uclampmax] command argument\nuclampset [options] [-m uclampmin] [-M uclampmax] -p PID\n\n## Flags\n\n| Flag | Long | Arg | Description |\n|------|------|-----|-------------|\n| -m | — | — | Set utilmin value. |\n| -M | — | — | Set utilmax value. |\n| -a | --all-tasks | — | Set or retrieve the utilization clamping attributes of all the tasks (threads) for a given PID. |\n| -p | --pid | — | Operate on an existing PID and do not launch a new task. |\n| -s | --system | — | Set or retrieve the system-wide utilization clamping attributes. |\n| -R | --reset-on-fork | — | Set SCHEDFLAGRESETONFORK flag. |\n| -v | --verbose | — | Show status information. |\n| -V | --version | — | Display version information and exit. |\n| -h | --help | — | Display help text and exit. |\n\n## See Also\n\n- nice(1)\n- renice(1)\n- taskset(1)\n- sched(7)\n- schedsetscheduler(2)\n- schedsetattr(2)\n\n## Section Outline\n\n- **NAME** (2 lines)\n- **SYNOPSIS** (4 lines)\n- **DESCRIPTION** (28 lines)\n- **OPTIONS** (1 lines) — 9 subsections\n - -m (2 lines)\n - -M (2 lines)\n - -a --all-tasks (3 lines)\n - -p --pid (2 lines)\n - -s --system (2 lines)\n - -R --reset-on-fork (2 lines)\n - -v --verbose (2 lines)\n - -V --version (2 lines)\n - -h --help (2 lines)\n- **USAGE** (12 lines)\n- **PERMISSIONS** (3 lines)\n- **NOTES** (13 lines)\n- **AUTHORS** (2 lines)\n- **SEE ALSO** (5 lines)\n- **REPORTING BUGS** (2 lines)\n- **AVAILABILITY** (6 lines)\n\n## Full Content\n\n### NAME\n\nuclampset - manipulate the utilization clamping attributes of the system or a process\n\n### SYNOPSIS\n\nuclampset [options] [-m uclampmin] [-M uclampmax] command argument\n\nuclampset [options] [-m uclampmin] [-M uclampmax] -p PID\n\n### DESCRIPTION\n\nuclampset sets or retrieves the utilization clamping attributes of an existing PID, or runs\ncommand with the given attributes.\n\nUtilization clamping is a new feature added in v5.3. It gives a hint to the scheduler about\nthe allowed range of utilization the task should be operating at.\n\nThe utilization of the task affects frequency selection and task placement. Only schedutil\ncpufreq governor understands handling util clamp hints at the time of writing. Consult your\nkernel docs for further info about other cpufreq governors support.\n\nIf you’re running on asymmetric heterogeneous system like Arm’s big.LITTLE. Utilization\nclamping can help bias task placement. If the task is boosted such that utilmin value is\nhigher than the little cores' capacity, then the scheduler will do its best to place it on a\nbig core.\n\nSimilarly, if utilmax is smaller than or equal the capacity of the little cores, then the\nscheduler can still choose to place it there even if the actual utilization of the task is at\nmax.\n\nSetting a task’s uclampmin to a none zero value will effectively boost the task as when it\nruns it’ll always start from this utilization value.\n\nBy setting a task’s uclampmax below 1024, this will effectively cap the task as when it runs\nit’ll never be able to go above this utilization value.\n\nThe full utilization range is: [0:1024]. The special value -1 is used to reset to system’s\ndefault.\n\n### OPTIONS\n\n#### -m\n\nSet utilmin value.\n\n#### -M\n\nSet utilmax value.\n\n#### -a --all-tasks\n\nSet or retrieve the utilization clamping attributes of all the tasks (threads) for a\ngiven PID.\n\n#### -p --pid\n\nOperate on an existing PID and do not launch a new task.\n\n#### -s --system\n\nSet or retrieve the system-wide utilization clamping attributes.\n\n#### -R --reset-on-fork\n\nSet SCHEDFLAGRESETONFORK flag.\n\n#### -v --verbose\n\nShow status information.\n\n#### -V --version\n\nDisplay version information and exit.\n\n#### -h --help\n\nDisplay help text and exit.\n\n### USAGE\n\nThe default behavior is to run a new command:\nuclampset [-m uclampmin] [-M uclampmax] command [arguments]\n\nYou can also retrieve the utilization clamping attributes of an existing task:\nuclampset -p PID\n\nOr set them:\nuclampset -p PID [-m uclampmin] [-M uclampmax]\n\nOr control the system-wide attributes:\nuclampset -s [-m uclampmin] [-M uclampmax]\n\n### PERMISSIONS\n\nA user must possess CAPSYSNICE to change the scheduling attributes of a process. Any user\ncan retrieve the scheduling information.\n\n### NOTES\n\nThe system wide utilization clamp attributes are there to control the allowed range the tasks\ncan use. By default both uclampmin and uclampmax are set to 1024. This means users can set\nthe utilization clamp values for their task across the full range [0:1024].\n\nFor example:\nuclampset -s -m 512 -M 700\n\nwill prevent any task from being boosted higher than 512. And all tasks in the systems are\ncapped to a utilization of 700. Effectively rendering the maximum performance of the system\nto 700.\n\nConsult your kernel docs for the exact expected behavior on that kernel.\n\n### AUTHORS\n\nQais Yousef \n\n### SEE ALSO\n\nnice(1), renice(1), taskset(1), sched(7)\n\nSee schedsetscheduler(2) and schedsetattr(2) for a description of the Linux scheduling\nscheme.\n\n### REPORTING BUGS\n\nFor bug reports, use the issue tracker at https://github.com/karelzak/util-linux/issues.\n\n### AVAILABILITY\n\nThe uclampset command is part of the util-linux package which can be downloaded from Linux\nKernel Archive .\n\n\n\nutil-linux 2.37.2 2021-06-02 UCLAMPSET(1)\n\n" } ], "structuredContent": { "command": "uclampset", "section": "1", "mode": "man", "summary": "uclampset - manipulate the utilization clamping attributes of the system or a process", "synopsis": "uclampset [options] [-m uclampmin] [-M uclampmax] command argument\nuclampset [options] [-m uclampmin] [-M uclampmax] -p PID", "tldr_summary": null, "tldr_examples": [], "tldr_source": null, "flags": [ { "flag": "-m", "long": null, "arg": null, "description": "Set utilmin value." }, { "flag": "-M", "long": null, "arg": null, "description": "Set utilmax value." }, { "flag": "-a", "long": "--all-tasks", "arg": null, "description": "Set or retrieve the utilization clamping attributes of all the tasks (threads) for a given PID." }, { "flag": "-p", "long": "--pid", "arg": null, "description": "Operate on an existing PID and do not launch a new task." }, { "flag": "-s", "long": "--system", "arg": null, "description": "Set or retrieve the system-wide utilization clamping attributes." }, { "flag": "-R", "long": "--reset-on-fork", "arg": null, "description": "Set SCHEDFLAGRESETONFORK flag." }, { "flag": "-v", "long": "--verbose", "arg": null, "description": "Show status information." }, { "flag": "-V", "long": "--version", "arg": null, "description": "Display version information and exit." }, { "flag": "-h", "long": "--help", "arg": null, "description": "Display help text and exit." } ], "examples": [], "see_also": [ { "name": "nice", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/nice/1/json" }, { "name": "renice", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/renice/1/json" }, { "name": "taskset", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/taskset/1/json" }, { "name": "sched", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/sched/7/json" }, { "name": "schedsetscheduler", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/schedsetscheduler/2/json" }, { "name": "schedsetattr", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/schedsetattr/2/json" } ], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "SYNOPSIS", "lines": 4, "subsections": [] }, { "name": "DESCRIPTION", "lines": 28, "subsections": [] }, { "name": "OPTIONS", "lines": 1, "subsections": [ { "name": "-m", "lines": 2, "flag": "-m" }, { "name": "-M", "lines": 2, "flag": "-M" }, { "name": "-a --all-tasks", "lines": 3, "flag": "-a", "long": "--all-tasks" }, { "name": "-p --pid", "lines": 2, "flag": "-p", "long": "--pid" }, { "name": "-s --system", "lines": 2, "flag": "-s", "long": "--system" }, { "name": "-R --reset-on-fork", "lines": 2, "flag": "-R", "long": "--reset-on-fork" }, { "name": "-v --verbose", "lines": 2, "flag": "-v", "long": "--verbose" }, { "name": "-V --version", "lines": 2, "flag": "-V", "long": "--version" }, { "name": "-h --help", "lines": 2, "flag": "-h", "long": "--help" } ] }, { "name": "USAGE", "lines": 12, "subsections": [] }, { "name": "PERMISSIONS", "lines": 3, "subsections": [] }, { "name": "NOTES", "lines": 13, "subsections": [] }, { "name": "AUTHORS", "lines": 2, "subsections": [] }, { "name": "SEE ALSO", "lines": 5, "subsections": [] }, { "name": "REPORTING BUGS", "lines": 2, "subsections": [] }, { "name": "AVAILABILITY", "lines": 6, "subsections": [] } ], "sections": { "NAME": { "content": "uclampset - manipulate the utilization clamping attributes of the system or a process\n", "subsections": [] }, "SYNOPSIS": { "content": "uclampset [options] [-m uclampmin] [-M uclampmax] command argument\n\nuclampset [options] [-m uclampmin] [-M uclampmax] -p PID\n", "subsections": [] }, "DESCRIPTION": { "content": "uclampset sets or retrieves the utilization clamping attributes of an existing PID, or runs\ncommand with the given attributes.\n\nUtilization clamping is a new feature added in v5.3. It gives a hint to the scheduler about\nthe allowed range of utilization the task should be operating at.\n\nThe utilization of the task affects frequency selection and task placement. Only schedutil\ncpufreq governor understands handling util clamp hints at the time of writing. Consult your\nkernel docs for further info about other cpufreq governors support.\n\nIf you’re running on asymmetric heterogeneous system like Arm’s big.LITTLE. Utilization\nclamping can help bias task placement. If the task is boosted such that utilmin value is\nhigher than the little cores' capacity, then the scheduler will do its best to place it on a\nbig core.\n\nSimilarly, if utilmax is smaller than or equal the capacity of the little cores, then the\nscheduler can still choose to place it there even if the actual utilization of the task is at\nmax.\n\nSetting a task’s uclampmin to a none zero value will effectively boost the task as when it\nruns it’ll always start from this utilization value.\n\nBy setting a task’s uclampmax below 1024, this will effectively cap the task as when it runs\nit’ll never be able to go above this utilization value.\n\nThe full utilization range is: [0:1024]. The special value -1 is used to reset to system’s\ndefault.\n", "subsections": [] }, "OPTIONS": { "content": "", "subsections": [ { "name": "-m", "content": "Set utilmin value.\n", "flag": "-m" }, { "name": "-M", "content": "Set utilmax value.\n", "flag": "-M" }, { "name": "-a --all-tasks", "content": "Set or retrieve the utilization clamping attributes of all the tasks (threads) for a\ngiven PID.\n", "flag": "-a", "long": "--all-tasks" }, { "name": "-p --pid", "content": "Operate on an existing PID and do not launch a new task.\n", "flag": "-p", "long": "--pid" }, { "name": "-s --system", "content": "Set or retrieve the system-wide utilization clamping attributes.\n", "flag": "-s", "long": "--system" }, { "name": "-R --reset-on-fork", "content": "Set SCHEDFLAGRESETONFORK flag.\n", "flag": "-R", "long": "--reset-on-fork" }, { "name": "-v --verbose", "content": "Show status information.\n", "flag": "-v", "long": "--verbose" }, { "name": "-V --version", "content": "Display version information and exit.\n", "flag": "-V", "long": "--version" }, { "name": "-h --help", "content": "Display help text and exit.\n", "flag": "-h", "long": "--help" } ] }, "USAGE": { "content": "The default behavior is to run a new command:\nuclampset [-m uclampmin] [-M uclampmax] command [arguments]\n\nYou can also retrieve the utilization clamping attributes of an existing task:\nuclampset -p PID\n\nOr set them:\nuclampset -p PID [-m uclampmin] [-M uclampmax]\n\nOr control the system-wide attributes:\nuclampset -s [-m uclampmin] [-M uclampmax]\n", "subsections": [] }, "PERMISSIONS": { "content": "A user must possess CAPSYSNICE to change the scheduling attributes of a process. Any user\ncan retrieve the scheduling information.\n", "subsections": [] }, "NOTES": { "content": "The system wide utilization clamp attributes are there to control the allowed range the tasks\ncan use. By default both uclampmin and uclampmax are set to 1024. This means users can set\nthe utilization clamp values for their task across the full range [0:1024].\n\nFor example:\nuclampset -s -m 512 -M 700\n\nwill prevent any task from being boosted higher than 512. And all tasks in the systems are\ncapped to a utilization of 700. Effectively rendering the maximum performance of the system\nto 700.\n\nConsult your kernel docs for the exact expected behavior on that kernel.\n", "subsections": [] }, "AUTHORS": { "content": "Qais Yousef \n", "subsections": [] }, "SEE ALSO": { "content": "nice(1), renice(1), taskset(1), sched(7)\n\nSee schedsetscheduler(2) and schedsetattr(2) for a description of the Linux scheduling\nscheme.\n", "subsections": [] }, "REPORTING BUGS": { "content": "For bug reports, use the issue tracker at https://github.com/karelzak/util-linux/issues.\n", "subsections": [] }, "AVAILABILITY": { "content": "The uclampset command is part of the util-linux package which can be downloaded from Linux\nKernel Archive .\n\n\n\nutil-linux 2.37.2 2021-06-02 UCLAMPSET(1)", "subsections": [] } } } }