mi_switch cpu_switch cpu_throw - switch to another thread context
records the amount of time the current thread has been running in the process structures and checks this value against the CPU time limits allocated to the process (see getrlimit(2)). Exceeding the soft limit results in a SIGXCPU signal to be posted to the process, while exceeding the hard limit will cause a SIGKILL
If the thread is still in the
will put it back onto the run queue, assuming that it will want to run again soon. If it is in one of the other states and KSE threading is enabled, the associated KSE will be made available to any higher priority threads from the same group, to allow them to be scheduled next.
After these administrative tasks are done,
hands over control to the machine dependent routine cpu_switch (,);
which will perform the actual thread context switch.
first saves the context of the current thread. Next, it calls choosethread ();
to determine which thread to run next. Finally, it reads in the saved context of the new thread and starts to execute the new thread.
is similar to cpu_switch ();
except that it does not save the context of the old thread. This function is useful when the kernel does not have an old thread context to save, such as when CPUs other than the boot CPU perform their first task switch, or when the kernel does not care about the state of the old thread, such as in thread_exit ();
when the kernel terminates the current thread and switches into a new thread.
To protect the runqueue(9), all of these functions must be called with the sched_lock mutex held.
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Created 1996-2020 by Maxim Chirkov
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