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1a87a0da66
and pmap_copy_page(). This gets rid of a couple more physical addresses in upper layers, with the eventual aim of supporting PAE and dealing with the physical addressing mostly within pmap. (We will need either 64 bit physical addresses or page indexes, possibly both depending on the circumstances. Leaving this to pmap itself gives more flexibilitly.) Reviewed by: jake Tested on: i386, ia64 and (I believe) sparc64. (my alpha was hosed)
150 lines
3.5 KiB
C
150 lines
3.5 KiB
C
/*-
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* Copyright (c) 1994 John Dyson
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* Copyright (c) 2001 Matt Dillon
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*
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* All rights reserved. Terms for use and redistribution
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* are covered by the BSD Copyright as found in /usr/src/COPYRIGHT.
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*
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* from: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91
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* Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <sys/vmmeter.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/sysctl.h>
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#include <sys/kthread.h>
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#include <vm/vm.h>
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#include <vm/vm_page.h>
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SYSCTL_DECL(_vm_stats_misc);
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static int cnt_prezero;
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SYSCTL_INT(_vm_stats_misc, OID_AUTO,
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cnt_prezero, CTLFLAG_RD, &cnt_prezero, 0, "");
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static int idlezero_enable = 0;
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SYSCTL_INT(_vm, OID_AUTO, idlezero_enable, CTLFLAG_RW, &idlezero_enable, 0, "");
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TUNABLE_INT("vm.idlezero_enable", &idlezero_enable);
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static int idlezero_maxrun = 16;
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SYSCTL_INT(_vm, OID_AUTO, idlezero_maxrun, CTLFLAG_RW, &idlezero_maxrun, 0, "");
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TUNABLE_INT("vm.idlezero_maxrun", &idlezero_maxrun);
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/*
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* Implement the pre-zeroed page mechanism.
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*/
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#define ZIDLE_LO(v) ((v) * 2 / 3)
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#define ZIDLE_HI(v) ((v) * 4 / 5)
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static int zero_state;
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static int
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vm_page_zero_check(void)
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{
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if (!idlezero_enable)
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return 0;
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/*
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* Attempt to maintain approximately 1/2 of our free pages in a
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* PG_ZERO'd state. Add some hysteresis to (attempt to) avoid
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* generally zeroing a page when the system is near steady-state.
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* Otherwise we might get 'flutter' during disk I/O / IPC or
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* fast sleeps. We also do not want to be continuously zeroing
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* pages because doing so may flush our L1 and L2 caches too much.
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*/
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if (zero_state && vm_page_zero_count >= ZIDLE_LO(cnt.v_free_count))
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return 0;
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if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count))
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return 0;
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return 1;
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}
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static int
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vm_page_zero_idle(void)
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{
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static int free_rover;
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vm_page_t m;
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mtx_lock(&Giant);
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zero_state = 0;
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m = vm_pageq_find(PQ_FREE, free_rover, FALSE);
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if (m != NULL && (m->flags & PG_ZERO) == 0) {
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vm_page_queues[m->queue].lcnt--;
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TAILQ_REMOVE(&vm_page_queues[m->queue].pl, m, pageq);
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m->queue = PQ_NONE;
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/* maybe drop out of Giant here */
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pmap_zero_page(m);
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/* and return here */
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vm_page_flag_set(m, PG_ZERO);
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m->queue = PQ_FREE + m->pc;
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vm_page_queues[m->queue].lcnt++;
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TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m,
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pageq);
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++vm_page_zero_count;
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++cnt_prezero;
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if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count))
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zero_state = 1;
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}
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free_rover = (free_rover + PQ_PRIME2) & PQ_L2_MASK;
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mtx_unlock(&Giant);
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return 1;
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}
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/* Called by vm_page_free to hint that a new page is available */
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void
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vm_page_zero_idle_wakeup(void)
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{
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if (vm_page_zero_check())
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wakeup(&zero_state);
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}
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static void
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vm_pagezero(void)
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{
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struct thread *td = curthread;
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struct rtprio rtp;
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int pages = 0;
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rtp.prio = RTP_PRIO_MAX;
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rtp.type = RTP_PRIO_IDLE;
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mtx_lock_spin(&sched_lock);
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rtp_to_pri(&rtp, td->td_ksegrp);
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mtx_unlock_spin(&sched_lock);
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for (;;) {
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if (vm_page_zero_check()) {
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pages += vm_page_zero_idle();
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if (pages > idlezero_maxrun) {
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mtx_lock_spin(&sched_lock);
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setrunqueue(td);
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td->td_proc->p_stats->p_ru.ru_nvcsw++;
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mi_switch();
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mtx_unlock_spin(&sched_lock);
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pages = 0;
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}
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} else {
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tsleep(&zero_state, PPAUSE, "pgzero", hz * 300);
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pages = 0;
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}
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}
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}
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static struct proc *pagezero;
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static struct kproc_desc pagezero_kp = {
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"pagezero",
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vm_pagezero,
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&pagezero
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};
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SYSINIT(pagezero, SI_SUB_KTHREAD_VM, SI_ORDER_ANY, kproc_start, &pagezero_kp)
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