ggd(1M)                                                                ggd(1M)


NAME
     ggd - rate-guarantee-granting daemon

SYNOPSIS
     ggd [ -v dbglevel ] [ -c cpunum ] [ -o iosize ]

DESCRIPTION
     ggd manages the I/O-rate guarantees that have been granted to processes
     on the system.  The daemon is started from a script in the /etc/rc2.d
     directory.  It reads the /etc/grio_disks file to obtain information about
     the available hardware devices.  Processes can make requests for I/O-rate
     guarantees by using the grio_action_list(3X), grio_reserve_file(3X), or
     grio_reserve_fs(3X) library calls.  After determining if the I/O rate can
     be guaranteed, the daemon returns a confirmation or rejection to the
     calling process.

     The /etc/grio_disks file is only read when the daemon is started.  If
     this file is edited, the daemon must be stopped and restarted in order to
     use the new information.

     The -v option causes the ggd daemon to display verbose execution
     information.  The dbglevel can be set from 0 to 10.  0 indicating no
     verbose output, and 10 indicating most verbose output.  The -o option
     allows the specification of an optimal iosize other than the default
     value of 64K. The iosize is specified as 64, 128, 256 or 512.  The -c
     option causes the daemon to mark the given cpunum cpu as a real-time cpu.
     The cpu is isolated from the rest of the processors on the system and the
     ggd daemon is allowed to only run on this cpu.  See the sysmp(2)
     reference page for more information on real-time processing.

FILES
     /etc/grio_disks

SEE ALSO
     sysmp(2), grio_associate_file(3X), grio_query_fs(3X),
     grio_action_list(3X), grio_reserve_file(3X), grio_reserve_fs(3X),
     grio_unreserve_bw(3X), grio_disks(4).

NOTES
     If the ggd daemon is killed and restarted, all previous rate guarantees
     become invalid.  It creates a lock file, /tmp/grio.lock, to prevent more
     than one copy of the daemon from running concurrently.  To make grio more
     secure, ggd has to be run with the priviledge of CAP_DEVICE_MGMT or as
     root.


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