b40ce4165d
Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha
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(VM_PAGE_TO_PHYS(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->kg_pri);
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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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