| MI_SWITCH(9) | Kernel Developer's Manual | MI_SWITCH(9) | 
mi_switch —
mi_switch(struct
  lwp *l);
mi_switch() function implements the
  machine-independent prelude to an LWP context switch. It is called from only a
  few distinguished places in the kernel code as a result of the principle of
  non-preemptable kernel mode execution. The three major uses of
  mi_switch() can be enumerated as follows:
mi_switch() records the amount of time the
    current LWP has been running in the LWP structure and checks this value
    against the CPU time limits allocated to the LWP (see
    getrlimit(2)). Exceeding
    the soft limit results in a SIGXCPU signal to be
    posted to the LWP, while exceeding the hard limit will cause a
    SIGKILL.
Unless l->l_switchto is not
    NULL, mi_switch() will call
    sched_nextlwp() to select a new LWP from the
    scheduler's runqueue structures. If no runnable LWP is found, the idle LWP
    is used. If the new LWP is not equal to the current one,
    mi_switch() will hand over control to the
    machine-dependent function
    cpu_switchto(9) to
    switch to the new LWP.
mi_switch() has to be called with the LWP
    lock held (through calling lwp_lock() first) and at
    the splsched(9) interrupt
    protection level. It returns with the LWP lock released.
mi_switch() returns 1 if a context switch was performed
  to a different LWP, 0 otherwise.
| July 21, 2007 | NetBSD 9.3 |