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Commands Reference, Volume 5
schedtune Command
Purpose
Compatibility script to set parameters of the CPU scheduler
and Virtual Memory Manager.
Syntax
schedtune [ -D ]
schedtune [ -d Number ] [ -e Number ] [ -f Number ] [ -h Number ] [ -m Number ] [ -p Number ] [ -r Number ] [ -t Number ] [ -w Number ]
Description
The schedtune sample program is being phased out
and will not be supported in future releases. It is being replaced by the schedo command which can be used to set the same parameters
as schedtune did in previous release. In AIX 5.2,
a compatibility script calling schedo is provided to
help the transition.
The schedtune command can only be executed by root.
Changes made by the schedtune command last until the
next reboot of the system. In AIX 5.2, schedo can
be used to make changes permanent.
Attention: Misuse of this scipt can cause performance
degradation or operating-system failure. Be sure that you have studied the
appropriate tuning sections of the AIX 5L Version 5.2 Performance Management Guide before using schedtune to change system parameters.
Flags
If no flags are specified, schedo -a is
called to display the current values.
-D |
Calls schedo -D to restore the default values. |
-a Number |
Calls schedo -o affinity_lim=Number to set the number
of context switches after which the SCHED_FIF02 policy no longer favors a
thread. |
-b Number |
Calls schedo -o idle_migration_barrier=Number to set the idle
migration barrier. |
-c Number |
Calls schedo -o %usDelta=Number to control the adjustment
of the clock drift. |
-d Number |
Calls schedo -o sched_D=Number to set the factor used to
decay CPU usage. |
-e Number |
Calls schedo -o v_exempt_seconds=Number to set the time
before a recently suspended and resumed process is eligible for resuspension. |
-f Number |
Calls schedo -o pacefork=Number to set the number of clock
ticks to delay before retrying a failed fork call. |
-F Number |
Calls schedo -o fixed_pri_global=Number to keep fixed priority
threads in the global run queue. |
-h Number |
Calls schedo -o v_repage_hi=Number to change the system
wide criterion used to determine when process suspension begins and ends. |
-m Number |
Calls schedo -o v_min_process=Number to set the minimum
multiprogramming level. |
-p Number |
Calls schedo -o v_repage_proc=Number to change the per
process criterion used to determine which processes to suspend. |
-r Number |
Calls schedo -o sched_R=Number to set the rate at which
to accumulate CPU usage. |
-s Number |
Calls schedo -o maxspin=Number to set the number of times
to spin on a lock before sleeping. |
-t Number |
Calls schedo -o timesplice=Number to set the number
of 10ms time slices. |
-w Number |
Calls schedo -o v_sec_wait=Number to set the number
of seconds to wait after thrashing ends before adding processes back into
the mix. |
-? |
Displays a brief description of the command and its parameters. |
See the schedo command's Tunable Parameters section.
Related Information
The schedo command
Real-Memory management.
Modifications to vmtune and schedtune in AIX 5L Version 5.2 Performance Management Guide.
Tuning VMM Memory Load Control with the schedtune
Command.
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