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curproc(9) [netbsd man page]

CURPROC(9)						   BSD Kernel Developer's Manual						CURPROC(9)

NAME
curproc, curcpu, curlwp -- current process, processor, and LWP SYNOPSIS
#include <sys/proc.h> struct cpu_info * curcpu(void); struct proc * curproc(void); struct lwp * curlwp(void); DESCRIPTION
The following macros can be used to retrieve the current processor, process, and light-weight process (LWP), respectively: 1. The machine-dependent curcpu() macro returns a pointer to a cpu_info structure containing information of the CPU that this thread is running on. 2. The machine-independent curproc() macro refers to a pointer to the process currently running on this CPU. 3. The curlwp() macro expands to a pointer to lwp structure, containing information about the current LWP. This macro is machine- independent, but machine-dependent <machine/cpu.h> may redefine it. SEE ALSO
cpu_number(9), proc_find(9) BSD
July 1, 2010 BSD

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MI_SWITCH(9)						   BSD Kernel Developer's Manual					      MI_SWITCH(9)

NAME
mi_switch -- machine independent context switch prelude SYNOPSIS
int mi_switch(struct lwp *l); DESCRIPTION
The 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: 1. From within cv_wait(9) and associated methods when the current LWP voluntarily relinquishes the CPU to wait for some resource to become available. 2. From within preempt(9) when the current LWP voluntarily relinquishes the CPU or when the kernel prepares a return to user-mode execution. 3. In the signal handling code if a signal is delivered that causes an LWP to stop (see issignal(9)). 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 lim- its 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. RETURN VALUES
mi_switch() returns 1 if a context switch was performed to a different LWP, 0 otherwise. SEE ALSO
condvar(9), cpu_switchto(9), csf(9), pmap(9), ras(9), sched_4bsd(9), splsched(9) BSD
July 21, 2007 BSD
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