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System Administration Guide: Resource Management and Network Services

How to Use prctl

As superuser, type prctl to display the maximum file descriptor for the current shell that is running:


# prctl -n process.max-file-descriptor $$
8437:   sh
process.max-file-descriptor              [ lowerable deny ]
                          256 basic      deny
                        65536 privileged deny
                   2147483647 system     deny

Use the prctl command to temporarily add a new privileged value to deny the use of more than three LWPs per task for the x-files project. The result is identical to the result in How to Set the Maximum Number of LWPs for Each Task in a Project, as shown in the following annotated sample session:


# newtask -p x-files

# id -p
uid=0(root) gid=1(other) projid=101(x-files)

# prctl -n task.max-lwps -t privileged -v 3 -e deny -i project x-files

# prctl -n task.max-lwps -i project x-files
670:    sh
task.max-lwps
                            3 privileged deny
                   2147483647 system     deny

You can also use prctl -r to change the lowest value of a resource control.


# prctl -n process.max-file-descriptor -r -v 128 $$