vm_zeroidle.c revision 131481
179265Sdillon/*- 279265Sdillon * Copyright (c) 1994 John Dyson 379265Sdillon * Copyright (c) 2001 Matt Dillon 479265Sdillon * 5118848Simp * All Rights Reserved. 6118848Simp * Redistribution and use in source and binary forms, with or without 7118848Simp * modification, are permitted provided that the following conditions 8118848Simp * are met: 9118848Simp * 1. Redistributions of source code must retain the above copyright 10118848Simp * notice, this list of conditions and the following disclaimer. 11118848Simp * 2. Redistributions in binary form must reproduce the above copyright 12118848Simp * notice, this list of conditions and the following disclaimer in the 13118848Simp * documentation and/or other materials provided with the distribution. 14118848Simp * 4. Neither the name of the University nor the names of its contributors 15118848Simp * may be used to endorse or promote products derived from this software 16118848Simp * without specific prior written permission. 1779265Sdillon * 18118848Simp * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 19118848Simp * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 20118848Simp * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21118848Simp * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 22118848Simp * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23118848Simp * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE 24118848Simp * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25118848Simp * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 26118848Simp * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 27118848Simp * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 28118848Simp * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29118848Simp * 3079265Sdillon * from: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91 3179265Sdillon * Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$ 32126588Sbde * from: FreeBSD: .../i386/vm_machdep.c,v 1.165 2001/07/04 23:27:04 dillon 3379265Sdillon */ 3479265Sdillon 35116226Sobrien#include <sys/cdefs.h> 36116226Sobrien__FBSDID("$FreeBSD: head/sys/vm/vm_zeroidle.c 131481 2004-07-02 20:21:44Z jhb $"); 37116226Sobrien 3879265Sdillon#include <sys/param.h> 3979265Sdillon#include <sys/systm.h> 4082314Speter#include <sys/kernel.h> 4179265Sdillon#include <sys/proc.h> 4282314Speter#include <sys/resourcevar.h> 4379265Sdillon#include <sys/vmmeter.h> 4482314Speter#include <sys/lock.h> 4579265Sdillon#include <sys/mutex.h> 46104964Sjeff#include <sys/sched.h> 4779265Sdillon#include <sys/sysctl.h> 4882314Speter#include <sys/kthread.h> 49125314Sjeff#include <sys/unistd.h> 5079265Sdillon 5179265Sdillon#include <vm/vm.h> 5279265Sdillon#include <vm/vm_page.h> 5379265Sdillon 5479265SdillonSYSCTL_DECL(_vm_stats_misc); 5579265Sdillon 5679265Sdillonstatic int cnt_prezero; 57126588SbdeSYSCTL_INT(_vm_stats_misc, OID_AUTO, cnt_prezero, CTLFLAG_RD, 58126588Sbde &cnt_prezero, 0, ""); 5979265Sdillon 6099571Speterstatic int idlezero_enable = 1; 6182314SpeterSYSCTL_INT(_vm, OID_AUTO, idlezero_enable, CTLFLAG_RW, &idlezero_enable, 0, ""); 6282314SpeterTUNABLE_INT("vm.idlezero_enable", &idlezero_enable); 6382314Speter 6482314Speterstatic int idlezero_maxrun = 16; 6582314SpeterSYSCTL_INT(_vm, OID_AUTO, idlezero_maxrun, CTLFLAG_RW, &idlezero_maxrun, 0, ""); 6682314SpeterTUNABLE_INT("vm.idlezero_maxrun", &idlezero_maxrun); 6782314Speter 6879265Sdillon/* 6979265Sdillon * Implement the pre-zeroed page mechanism. 7079265Sdillon */ 7179265Sdillon 7279265Sdillon#define ZIDLE_LO(v) ((v) * 2 / 3) 7379265Sdillon#define ZIDLE_HI(v) ((v) * 4 / 5) 7479265Sdillon 7582314Speterstatic int zero_state; 7682314Speter 7782314Speterstatic int 7882314Spetervm_page_zero_check(void) 7979265Sdillon{ 8079265Sdillon 8182314Speter if (!idlezero_enable) 82126588Sbde return (0); 8379265Sdillon /* 8479265Sdillon * Attempt to maintain approximately 1/2 of our free pages in a 8579265Sdillon * PG_ZERO'd state. Add some hysteresis to (attempt to) avoid 8679265Sdillon * generally zeroing a page when the system is near steady-state. 8779265Sdillon * Otherwise we might get 'flutter' during disk I/O / IPC or 8879265Sdillon * fast sleeps. We also do not want to be continuously zeroing 8979265Sdillon * pages because doing so may flush our L1 and L2 caches too much. 9079265Sdillon */ 9179265Sdillon if (zero_state && vm_page_zero_count >= ZIDLE_LO(cnt.v_free_count)) 92126588Sbde return (0); 9379265Sdillon if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count)) 94126588Sbde return (0); 95126588Sbde return (1); 9682314Speter} 9779265Sdillon 9882314Speterstatic int 9982314Spetervm_page_zero_idle(void) 10082314Speter{ 10182314Speter static int free_rover; 10282314Speter vm_page_t m; 10382314Speter 10499625Speter mtx_lock_spin(&vm_page_queue_free_mtx); 10582314Speter zero_state = 0; 10682314Speter m = vm_pageq_find(PQ_FREE, free_rover, FALSE); 10782314Speter if (m != NULL && (m->flags & PG_ZERO) == 0) { 108100193Salc vm_pageq_remove_nowakeup(m); 10999625Speter mtx_unlock_spin(&vm_page_queue_free_mtx); 11099571Speter pmap_zero_page_idle(m); 11199625Speter mtx_lock_spin(&vm_page_queue_free_mtx); 112100331Salc m->flags |= PG_ZERO; 113100193Salc vm_pageq_enqueue(PQ_FREE + m->pc, m); 11482314Speter ++vm_page_zero_count; 11582314Speter ++cnt_prezero; 11682314Speter if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count)) 11782314Speter zero_state = 1; 11882314Speter } 11982314Speter free_rover = (free_rover + PQ_PRIME2) & PQ_L2_MASK; 12099625Speter mtx_unlock_spin(&vm_page_queue_free_mtx); 121126588Sbde return (1); 12282314Speter} 12382314Speter 124126588Sbde/* Called by vm_page_free to hint that a new page is available. */ 12582314Spetervoid 12682314Spetervm_page_zero_idle_wakeup(void) 12782314Speter{ 12882314Speter 12999571Speter if (idlezero_enable && vm_page_zero_check()) 13082314Speter wakeup(&zero_state); 13182314Speter} 13282314Speter 13382314Speterstatic void 134125314Sjeffvm_pagezero(void __unused *arg) 13582314Speter{ 136100379Speter struct proc *p; 13782314Speter struct rtprio rtp; 138126588Sbde struct thread *td; 139126588Sbde int pages, pri; 14082314Speter 141100379Speter td = curthread; 142100379Speter p = td->td_proc; 14382314Speter rtp.prio = RTP_PRIO_MAX; 14482314Speter rtp.type = RTP_PRIO_IDLE; 145126588Sbde pages = 0; 14682756Sjhb mtx_lock_spin(&sched_lock); 14790538Sjulian rtp_to_pri(&rtp, td->td_ksegrp); 14899571Speter pri = td->td_priority; 14982756Sjhb mtx_unlock_spin(&sched_lock); 15082314Speter 15182314Speter for (;;) { 15282314Speter if (vm_page_zero_check()) { 15382314Speter pages += vm_page_zero_idle(); 154131481Sjhb#ifndef PREEMPTION 155104964Sjeff if (pages > idlezero_maxrun || sched_runnable()) { 15682314Speter mtx_lock_spin(&sched_lock); 157131473Sjhb mi_switch(SW_VOL, NULL); 15882314Speter mtx_unlock_spin(&sched_lock); 15982314Speter pages = 0; 16082314Speter } 161131481Sjhb#endif 16282314Speter } else { 16399571Speter tsleep(&zero_state, pri, "pgzero", hz * 300); 16482314Speter pages = 0; 16579265Sdillon } 16679265Sdillon } 16779265Sdillon} 16879265Sdillon 169113070Sdesstatic struct proc *pagezero_proc; 170125314Sjeff 171125314Sjeffstatic void 172125314Sjeffpagezero_start(void __unused *arg) 173125314Sjeff{ 174125314Sjeff int error; 175125314Sjeff 176125314Sjeff error = kthread_create(vm_pagezero, NULL, &pagezero_proc, RFSTOPPED, 0, 177125314Sjeff "pagezero"); 178125314Sjeff if (error) 179125314Sjeff panic("pagezero_start: error %d\n", error); 180125314Sjeff /* 181125314Sjeff * We're an idle task, don't count us in the load. 182125314Sjeff */ 183125314Sjeff PROC_LOCK(pagezero_proc); 184125314Sjeff pagezero_proc->p_flag |= P_NOLOAD; 185125314Sjeff PROC_UNLOCK(pagezero_proc); 186125314Sjeff mtx_lock_spin(&sched_lock); 187125314Sjeff setrunqueue(FIRST_THREAD_IN_PROC(pagezero_proc)); 188125314Sjeff mtx_unlock_spin(&sched_lock); 189125314Sjeff} 190125314SjeffSYSINIT(pagezero, SI_SUB_KTHREAD_VM, SI_ORDER_ANY, pagezero_start, NULL) 191