coresched(1) — Linux manual page
CORESCHED(1) User Commands CORESCHED(1)
NAME
coresched - manage core scheduling cookies for tasks
SYNOPSIS
coresched [get] [-s pid]
coresched new [-t type] -d pid
coresched new [-t type] -- command [argument...]
coresched copy [-s pid] [-t type] -d pid
coresched copy [-s pid] [-t type] -- command [argument...]
DESCRIPTION
The coresched command is used to retrieve or modify the core
scheduling cookies of a running process given its pid, or to
spawn a new command with core scheduling cookies.
Core scheduling permits the definition of groups of tasks that
are allowed to share a physical core. This is done by assigning a
cookie to each task. Only tasks have the same cookie are allowed
to be scheduled on the same physical core.
It is possible to either assign a new random cookie to a task, or
copy a cookie from another task. It is not possible to choose the
value of the cookie.
FUNCTIONS
get
Retrieve the core scheduling cookie of the PID specified in
-s. If -s is omitted, it will get the cookie of the current
coresched process.
new
Assign a new cookie to an existing PID specified in -d, or
execute command with a new cookie.
copy
Copy the cookie from an existing PID (-s) to another PID
(-d), or execute command with that cookie. If -s is omitted,
it will get the cookie of the current coresched process.
If no function is specified, it will run the get function.
OPTIONS
-s, --source PID
Which PID to get the cookie from. If this option is omitted,
it will get the cookie from the current coresched process.
-d, --dest PID
Which PID to modify the cookie of.
-t, --dest-type TYPE
The type of the PID whose cookie will be modified. This can
be one of three values:
• pid, or process ID
• tgid, or thread group ID (default value)
• pgid, or process group ID
-v, --verbose
Show extra information when modifying cookies of tasks.
-h, --help
Display help text and exit.
-V, --version
Print version and exit.
EXAMPLES
Get the core scheduling cookie of the coresched task itself,
usually inherited from its parent:
coresched get
Get the core scheduling cookie of a task with PID 123:
coresched get -s 123
Give a task with PID 123 a new core scheduling cookie:
coresched new -d 123
Spawn a new task with a new core scheduling cookie:
coresched new -- command [argument...]
Copy the cookie from the current coresched process another task
with pid 456:
coresched copy -d 456
Copy the cookie from a task with pid 123 to another task with pid
456:
coresched copy -s 123 -d 456
Copy the cookie from a task with pid 123 to a new task command:
coresched copy -s 123 -- command [argument...]
Copy the cookie from a task with pid 123 to the process group ID
456:
coresched copy -s 123 -t pgid -d 456
PERMISSIONS
Retrieving or modifying the core scheduling cookie of a process
requires PTRACE_MODE_READ_REALCREDS ptrace access to that
process. See the section "Ptrace access mode checking" in
ptrace(2) for more information.
RETURN VALUE
On success, coresched returns 0. If coresched fails, it will
print an error and return 1.
If a command is being executed, the return value of coresched
will be the return value of command.
NOTES
coresched requires core scheduling support in the kernel. This
can be enabled via the CONFIG_SCHED_CORE kernel config option.
AUTHORS
Thijs Raymakers <thijs@raymakers.nl>, Phil Auld
<pauld@redhat.com>
COPYRIGHT
Copyright © 2024 Thijs Raymakers and Phil Auld. This is free
software licensed under the EUPL.
SEE ALSO
chrt(1), nice(1), renice(1), taskset(1), ptrace(2), sched(7)
The Linux kernel source files
Documentation/admin-guide/hw-vuln/core-scheduling.rst
REPORTING BUGS
For bug reports, use the issue tracker at
https://github.com/util-linux/util-linux/issues.
AVAILABILITY
The coresched command is part of the util-linux package which can
be downloaded from Linux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>. This page
is part of the util-linux (a random collection of Linux
utilities) project. Information about the project can be found at
⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have
a bug report for this manual page, send it to
util-linux@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
2024-06-14. (At that time, the date of the most recent commit
that was found in the repository was 2024-06-10.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in
this COLOPHON (which is not part of the original manual page),
send a mail to man-pages@man7.org