Associated with both scheduling classes is a parameter table, rt_dptbl(4), and ts_dptbl(4). These tables are configurable by using a loadable module at boot time, or with dispadmin(1M) during runtime.
The in-core table for realtime establishes the properties for RT scheduling. The rt_dptbl(4) structure consists of an array of parameters, struct rt_dpent_t, one for each of the n priority levels. The properties of a given priority level i are specified by the ith parameter structure in the array, rt_dptbl[i].
A parameter structure consists of the following members (also described in the /usr/include/sys/rt.h header file).
rt_globpri |
The global scheduling priority associated with this priority level. The rt_globpri values cannot be changed with dispadmin(1M). |
rt_quantum |
The length of the time quantum allocated to processes at this level in ticks (see "Timestamp Functions"). The time quantum value is only a default or starting value for processes at a particular level. The time quantum of a realtime process can be changed by using the priocntl(1) command or the priocntl(2) system call. |
A realtime administrator can change the behavior of the realtime portion of the scheduler by reconfiguring the config_rt_dptbl at any time. One method is described in rt_dptbl(4) in the section titled "REPLACING THE RT_DPTBL LOADABLE MODULE".
A second method for examining or modifying the realtime parameter table on a running system is through using the dispadmin(1M) command. Invoking dispadmin(1M) for the realtime class allows retrieval of the current rt_quantum values in the current config_rt_dptbl configuration from the kernel's in-core table. When overwriting the current in-core table, the configuration file used for input to dispadmin(1M)dispadmin must conform to the specific format described in rt_dptbl(4).
Following is an example of prioritized processes rtdpent_t with their associated time quantum config_rt_dptbl[] value as they might appear in config_rt_dptbl[].