test

System Interface Guide

Configuring Scheduling

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 Dispatcher Parameter Table

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.

Reconfiguring config_rt_dptbl

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[]. 

rtdpent_t   rt_dptbl[] = {       
      /* prilevel Time quantum */
                 100,    100,
                 101,    100,
                 102,    100,
                 103,    100,
                 104,    100,
                 105,    100,
                 106,    100,
                 107,    100,
                 108,    100,
                 109,    100,
                 110,    80,
                 111,    80,
                 112,    80,
                 113,    80,
                 114,    80,
                 115,    80,
                 116,    80,
                 117,    80,
                 118,    80,
                 119,    80,
                 120,    60,
                 121,    60,
                 122,    60,
                 123,    60,
                 124,    60,
                 125,    60,
                 126,    60,
                 127,    60,
                 128,    60,
                 129,    60,
                 130,    40,
                 131,    40,
                 132,    40,
                 133,    40,
               
                134,    40,
                 135,    40,
                 136,    40,
                 137,    40,
                 138,    40
                 139,    40,
                 140,    20,
                 141,    20,
                 142,    20,
                 143,    20,
                 144,    20,
                 145,    20,
                 146,    20,
                 147,    20,
                 148,    20,
                 149,    20,
                 150,    10,
                 151,    10,
                 152,    10,
                 153,    10,
                 154,    10,
                 155,    10,
                 156,    10,
                 157,    10,
                 158,    10,
                 159,    10,
 }