---
name: "coresched"
section: "1"
platform: "linux"
package: "util-linux"
version: "2.42.4-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/coresched"
---

# coresched(1)

manage core scheduling cookies for tasks

## 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**

  Display 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)](/ptrace/2.md) for more information.

## EXIT STATUS

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)](/chrt/1.md), [**nice**(1)](/nice/1.md), [**renice**(1)](/renice/1.md), [**taskset**(1)](/taskset/1.md), [**ptrace**(2)](/ptrace/2.md), [**sched**(7)](/sched/7.md)

The Linux kernel source files *Documentation/admin-guide/hw-vuln/core-scheduling.rst*

## REPORTING BUGS

For bug reports, use the *issue tracker* \<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/\>.