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 real-time establishes the properties for RT scheduling. The rt_dptbl(4) structure consists of an array of parameters, struct rt_dpent_t. Each of the n priority levels has one parameter. The properties of a given priority level are specified by the ith parameter structure in the array, rt_dptbl[i].
A parameter structure consists of the following members, which are also described in the /usr/include/sys/rt.h header file.
The global scheduling priority associated with this priority level. The rt_globpri values cannot be changed with dispadmin(1M).
The length of the time quantum allocated to processes at this level in ticks. For more information, see Timestamp Interfaces. The time quantum value is only a default or starting value for processes at a particular level. The time quantum of a real-time process can be changed by using the priocntl(1) command or the priocntl(2) system call.
A real-time administrator can change the behavior of the real-time portion of the scheduler by reconfiguring the config_rt_dptbl at any time. One method is described in the rt_dptbl(4) man page, in the section titled “Replacing the rt_dptbl Loadable Module.”
A second method for examining or modifying the real-time parameter table on a running system is through the dispadmin(1M) command. Invoking dispadmin(1M) for the real-time class enables 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) must conform to the specific format described in the rt_dptbl(4) man page.
Following is an example of prioritized processes rtdpent_t with their associated time quantum config_rt_dptbl[] value as the processes might appear in config_rt_dptbl[].
Example 11-1 RT Class Dispatch Parametersrtdpent_t rt_dptbl[] = { 129, 60, /* prilevel Time quantum */ 130, 40, 100, 100, 131, 40, 101, 100, 132, 40, 102, 100, 133, 40, 103, 100, 134, 40, 104, 100, 135, 40, 105, 100, 136, 40, 106, 100, 137, 40, 107, 100, 138, 40 108, 100, 139, 40, 109, 100, 140, 20, 110, 80, 141, 20, 111, 80, 142, 20, 112, 80, 143, 20, 113, 80, 144, 20, 114, 80, 145, 20, 115, 80, 146, 20, 116, 80, 147, 20, 117, 80, 148, 20, 118, 80, 149, 20, 119, 80, 150, 10, 120, 60, 151, 10, 121, 60, 152, 10, 122, 60, 153, 10, 123, 60, 154, 10, 124, 60, 155, 10, 125, 60, 156, 10, 126, 60, 157, 10, 126, 60, 158, 10, 127, 60, 159, 10, 128, 60, }