a665ae3de1
- contributed by Bjorn Swift - adds process accounting, for example counting the number of messages sent, how often the process was preemted and how much time it spent in the run queue. These statistics, along with the current cpu load, are sent back to the user-space scheduler in the Out Of Quantum message. - the user-space scheduler may choose to make use of these statistics when making scheduling decisions. For isntance the cpu load becomes especially useful when scheduling on multiple cores.
128 lines
4 KiB
C
128 lines
4 KiB
C
/* The kernel call implemented in this file:
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* m_type: SYS_FORK
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*
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* The parameters for this kernel call are:
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* m1_i1: PR_ENDPT (parent, process that forked)
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* m1_i2: PR_SLOT (child's process table slot)
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* m1_p1: PR_MEM_PTR (new memory map for the child)
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* m1_i3: PR_FORK_FLAGS (fork flags)
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*/
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#include "kernel/system.h"
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#include "kernel/vm.h"
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#include <signal.h>
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#include <string.h>
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#include <assert.h>
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#include <minix/endpoint.h>
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#include <minix/u64.h>
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#if USE_FORK
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/*===========================================================================*
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* do_fork *
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*===========================================================================*/
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PUBLIC int do_fork(struct proc * caller, message * m_ptr)
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{
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/* Handle sys_fork(). PR_ENDPT has forked. The child is PR_SLOT. */
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#if (_MINIX_CHIP == _CHIP_INTEL)
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reg_t old_ldt_sel;
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void *old_fpu_save_area_p;
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#endif
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register struct proc *rpc; /* child process pointer */
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struct proc *rpp; /* parent process pointer */
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struct mem_map *map_ptr; /* virtual address of map inside caller (PM) */
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int gen, r;
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int p_proc;
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if(!isokendpt(m_ptr->PR_ENDPT, &p_proc))
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return EINVAL;
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rpp = proc_addr(p_proc);
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rpc = proc_addr(m_ptr->PR_SLOT);
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if (isemptyp(rpp) || ! isemptyp(rpc)) return(EINVAL);
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assert(!(rpp->p_misc_flags & MF_DELIVERMSG));
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/* needs to be receiving so we know where the message buffer is */
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if(!RTS_ISSET(rpp, RTS_RECEIVING)) {
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printf("kernel: fork not done synchronously?\n");
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return EINVAL;
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}
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map_ptr= (struct mem_map *) m_ptr->PR_MEM_PTR;
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/* make sure that the FPU context is saved in parent before copy */
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save_fpu(rpp);
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/* Copy parent 'proc' struct to child. And reinitialize some fields. */
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gen = _ENDPOINT_G(rpc->p_endpoint);
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#if (_MINIX_CHIP == _CHIP_INTEL)
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old_ldt_sel = rpc->p_seg.p_ldt_sel; /* backup local descriptors */
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old_fpu_save_area_p = rpc->p_fpu_state.fpu_save_area_p;
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#endif
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*rpc = *rpp; /* copy 'proc' struct */
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#if (_MINIX_CHIP == _CHIP_INTEL)
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rpc->p_seg.p_ldt_sel = old_ldt_sel; /* restore descriptors */
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rpc->p_fpu_state.fpu_save_area_p = old_fpu_save_area_p;
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if(proc_used_fpu(rpp))
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memcpy(rpc->p_fpu_state.fpu_save_area_p,
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rpp->p_fpu_state.fpu_save_area_p,
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FPU_XFP_SIZE);
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#endif
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if(++gen >= _ENDPOINT_MAX_GENERATION) /* increase generation */
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gen = 1; /* generation number wraparound */
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rpc->p_nr = m_ptr->PR_SLOT; /* this was obliterated by copy */
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rpc->p_endpoint = _ENDPOINT(gen, rpc->p_nr); /* new endpoint of slot */
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rpc->p_reg.retreg = 0; /* child sees pid = 0 to know it is child */
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rpc->p_user_time = 0; /* set all the accounting times to 0 */
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rpc->p_sys_time = 0;
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rpc->p_reg.psw &= ~TRACEBIT; /* clear trace bit */
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rpc->p_misc_flags &= ~(MF_VIRT_TIMER | MF_PROF_TIMER | MF_SC_TRACE);
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rpc->p_virt_left = 0; /* disable, clear the process-virtual timers */
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rpc->p_prof_left = 0;
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/* the child process is not runnable until it's scheduled. */
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RTS_SET(rpc, RTS_NO_QUANTUM);
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reset_proc_accounting(rpc);
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make_zero64(rpc->p_cpu_time_left);
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make_zero64(rpc->p_cycles);
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/* If the parent is a privileged process, take away the privileges from the
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* child process and inhibit it from running by setting the NO_PRIV flag.
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* The caller should explicitely set the new privileges before executing.
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*/
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if (priv(rpp)->s_flags & SYS_PROC) {
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rpc->p_priv = priv_addr(USER_PRIV_ID);
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rpc->p_rts_flags |= RTS_NO_PRIV;
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}
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/* Calculate endpoint identifier, so caller knows what it is. */
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m_ptr->PR_ENDPT = rpc->p_endpoint;
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m_ptr->PR_FORK_MSGADDR = (char *) rpp->p_delivermsg_vir;
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/* Install new map */
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r = newmap(caller, rpc, map_ptr);
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/* Don't schedule process in VM mode until it has a new pagetable. */
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if(m_ptr->PR_FORK_FLAGS & PFF_VMINHIBIT) {
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RTS_SET(rpc, RTS_VMINHIBIT);
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}
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/*
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* Only one in group should have RTS_SIGNALED, child doesn't inherit tracing.
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*/
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RTS_UNSET(rpc, (RTS_SIGNALED | RTS_SIG_PENDING | RTS_P_STOP));
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(void) sigemptyset(&rpc->p_pending);
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rpc->p_seg.p_cr3 = 0;
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rpc->p_seg.p_cr3_v = NULL;
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return r;
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}
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#endif /* USE_FORK */
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