vm_zeroidle.c revision 161489
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 161489 2006-08-21 00:55:05Z alc $"); 37116226Sobrien 38134649Sscottl#include <opt_sched.h> 39134649Sscottl 4079265Sdillon#include <sys/param.h> 4179265Sdillon#include <sys/systm.h> 4282314Speter#include <sys/kernel.h> 4379265Sdillon#include <sys/proc.h> 4479265Sdillon#include <sys/vmmeter.h> 4582314Speter#include <sys/lock.h> 4679265Sdillon#include <sys/mutex.h> 47104964Sjeff#include <sys/sched.h> 4879265Sdillon#include <sys/sysctl.h> 4982314Speter#include <sys/kthread.h> 50125314Sjeff#include <sys/unistd.h> 5179265Sdillon 5279265Sdillon#include <vm/vm.h> 5379265Sdillon#include <vm/vm_page.h> 5479265Sdillon 5579265SdillonSYSCTL_DECL(_vm_stats_misc); 5679265Sdillon 5779265Sdillonstatic int cnt_prezero; 58126588SbdeSYSCTL_INT(_vm_stats_misc, OID_AUTO, cnt_prezero, CTLFLAG_RD, 59126588Sbde &cnt_prezero, 0, ""); 6079265Sdillon 61134461Siedowsestatic int idlezero_enable_default = 1; 62134461SiedowseTUNABLE_INT("vm.idlezero_enable", &idlezero_enable_default); 63134461Siedowse/* Defer setting the enable flag until the kthread is running. */ 64134461Siedowsestatic int idlezero_enable = 0; 6582314SpeterSYSCTL_INT(_vm, OID_AUTO, idlezero_enable, CTLFLAG_RW, &idlezero_enable, 0, ""); 6682314Speter 6782314Speterstatic int idlezero_maxrun = 16; 6882314SpeterSYSCTL_INT(_vm, OID_AUTO, idlezero_maxrun, CTLFLAG_RW, &idlezero_maxrun, 0, ""); 6982314SpeterTUNABLE_INT("vm.idlezero_maxrun", &idlezero_maxrun); 7082314Speter 7179265Sdillon/* 7279265Sdillon * Implement the pre-zeroed page mechanism. 7379265Sdillon */ 7479265Sdillon 7579265Sdillon#define ZIDLE_LO(v) ((v) * 2 / 3) 7679265Sdillon#define ZIDLE_HI(v) ((v) * 4 / 5) 7779265Sdillon 78137104Salcstatic boolean_t wakeup_needed = FALSE; 7982314Speterstatic int zero_state; 8082314Speter 8182314Speterstatic int 8282314Spetervm_page_zero_check(void) 8379265Sdillon{ 8479265Sdillon 8582314Speter if (!idlezero_enable) 86126588Sbde return (0); 8779265Sdillon /* 8879265Sdillon * Attempt to maintain approximately 1/2 of our free pages in a 8979265Sdillon * PG_ZERO'd state. Add some hysteresis to (attempt to) avoid 9079265Sdillon * generally zeroing a page when the system is near steady-state. 9179265Sdillon * Otherwise we might get 'flutter' during disk I/O / IPC or 9279265Sdillon * fast sleeps. We also do not want to be continuously zeroing 9379265Sdillon * pages because doing so may flush our L1 and L2 caches too much. 9479265Sdillon */ 9579265Sdillon if (zero_state && vm_page_zero_count >= ZIDLE_LO(cnt.v_free_count)) 96126588Sbde return (0); 9779265Sdillon if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count)) 98126588Sbde return (0); 99126588Sbde return (1); 10082314Speter} 10179265Sdillon 102161489Salcstatic void 10382314Spetervm_page_zero_idle(void) 10482314Speter{ 10582314Speter static int free_rover; 10682314Speter vm_page_t m; 10782314Speter 10899625Speter mtx_lock_spin(&vm_page_queue_free_mtx); 10982314Speter zero_state = 0; 11082314Speter m = vm_pageq_find(PQ_FREE, free_rover, FALSE); 11182314Speter if (m != NULL && (m->flags & PG_ZERO) == 0) { 112100193Salc vm_pageq_remove_nowakeup(m); 11399625Speter mtx_unlock_spin(&vm_page_queue_free_mtx); 11499571Speter pmap_zero_page_idle(m); 11599625Speter mtx_lock_spin(&vm_page_queue_free_mtx); 116100331Salc m->flags |= PG_ZERO; 117100193Salc vm_pageq_enqueue(PQ_FREE + m->pc, m); 11882314Speter ++vm_page_zero_count; 11982314Speter ++cnt_prezero; 12082314Speter if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count)) 12182314Speter zero_state = 1; 12282314Speter } 123153940Snetchild free_rover = (free_rover + PQ_PRIME2) & PQ_COLORMASK; 12499625Speter mtx_unlock_spin(&vm_page_queue_free_mtx); 12582314Speter} 12682314Speter 127126588Sbde/* Called by vm_page_free to hint that a new page is available. */ 12882314Spetervoid 12982314Spetervm_page_zero_idle_wakeup(void) 13082314Speter{ 13182314Speter 132137104Salc mtx_assert(&vm_page_queue_mtx, MA_OWNED); 133137104Salc if (wakeup_needed && vm_page_zero_check()) { 134137104Salc wakeup_needed = FALSE; 13582314Speter wakeup(&zero_state); 136137104Salc } 13782314Speter} 13882314Speter 13982314Speterstatic void 140125314Sjeffvm_pagezero(void __unused *arg) 14182314Speter{ 14282314Speter 143134461Siedowse idlezero_enable = idlezero_enable_default; 14482314Speter 14582314Speter for (;;) { 14682314Speter if (vm_page_zero_check()) { 147137268Sjhb vm_page_zero_idle(); 148131481Sjhb#ifndef PREEMPTION 149137268Sjhb if (sched_runnable()) { 15082314Speter mtx_lock_spin(&sched_lock); 151131473Sjhb mi_switch(SW_VOL, NULL); 15282314Speter mtx_unlock_spin(&sched_lock); 15382314Speter } 154131481Sjhb#endif 15582314Speter } else { 156137104Salc vm_page_lock_queues(); 157137104Salc wakeup_needed = TRUE; 158137268Sjhb msleep(&zero_state, &vm_page_queue_mtx, 159157815Sjhb PDROP, "pgzero", hz * 300); 16079265Sdillon } 16179265Sdillon } 16279265Sdillon} 16379265Sdillon 164113070Sdesstatic struct proc *pagezero_proc; 165125314Sjeff 166125314Sjeffstatic void 167125314Sjeffpagezero_start(void __unused *arg) 168125314Sjeff{ 169125314Sjeff int error; 170141247Sssouhlal struct thread *td; 171125314Sjeff 172125314Sjeff error = kthread_create(vm_pagezero, NULL, &pagezero_proc, RFSTOPPED, 0, 173125314Sjeff "pagezero"); 174125314Sjeff if (error) 175125314Sjeff panic("pagezero_start: error %d\n", error); 176125314Sjeff /* 177125314Sjeff * We're an idle task, don't count us in the load. 178125314Sjeff */ 179125314Sjeff PROC_LOCK(pagezero_proc); 180125314Sjeff pagezero_proc->p_flag |= P_NOLOAD; 181125314Sjeff PROC_UNLOCK(pagezero_proc); 182125314Sjeff mtx_lock_spin(&sched_lock); 183141247Sssouhlal td = FIRST_THREAD_IN_PROC(pagezero_proc); 184141247Sssouhlal sched_class(td->td_ksegrp, PRI_IDLE); 185141247Sssouhlal sched_prio(td, PRI_MAX_IDLE); 186141247Sssouhlal setrunqueue(td, SRQ_BORING); 187125314Sjeff mtx_unlock_spin(&sched_lock); 188125314Sjeff} 189125314SjeffSYSINIT(pagezero, SI_SUB_KTHREAD_VM, SI_ORDER_ANY, pagezero_start, NULL) 190