vm_zeroidle.c revision 125314
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 $Hdr: vm_machdep.c 1.16.1.1 89/06/23$ 3279265Sdillon */ 3379265Sdillon 34116226Sobrien#include <sys/cdefs.h> 35116226Sobrien__FBSDID("$FreeBSD: head/sys/vm/vm_zeroidle.c 125314 2004-02-02 07:51:03Z jeff $"); 36116226Sobrien 3779265Sdillon#include <sys/param.h> 3879265Sdillon#include <sys/systm.h> 3982314Speter#include <sys/kernel.h> 4079265Sdillon#include <sys/proc.h> 4182314Speter#include <sys/resourcevar.h> 4279265Sdillon#include <sys/vmmeter.h> 4382314Speter#include <sys/lock.h> 4479265Sdillon#include <sys/mutex.h> 45104964Sjeff#include <sys/sched.h> 4679265Sdillon#include <sys/sysctl.h> 4782314Speter#include <sys/kthread.h> 48125314Sjeff#include <sys/unistd.h> 4979265Sdillon 5079265Sdillon#include <vm/vm.h> 5179265Sdillon#include <vm/vm_page.h> 5279265Sdillon 5379265SdillonSYSCTL_DECL(_vm_stats_misc); 5479265Sdillon 5579265Sdillonstatic int cnt_prezero; 5679265SdillonSYSCTL_INT(_vm_stats_misc, OID_AUTO, 5779265Sdillon cnt_prezero, CTLFLAG_RD, &cnt_prezero, 0, ""); 5879265Sdillon 5999571Speterstatic int idlezero_enable = 1; 6082314SpeterSYSCTL_INT(_vm, OID_AUTO, idlezero_enable, CTLFLAG_RW, &idlezero_enable, 0, ""); 6182314SpeterTUNABLE_INT("vm.idlezero_enable", &idlezero_enable); 6282314Speter 6382314Speterstatic int idlezero_maxrun = 16; 6482314SpeterSYSCTL_INT(_vm, OID_AUTO, idlezero_maxrun, CTLFLAG_RW, &idlezero_maxrun, 0, ""); 6582314SpeterTUNABLE_INT("vm.idlezero_maxrun", &idlezero_maxrun); 6682314Speter 6779265Sdillon/* 6879265Sdillon * Implement the pre-zeroed page mechanism. 6979265Sdillon */ 7079265Sdillon 7179265Sdillon#define ZIDLE_LO(v) ((v) * 2 / 3) 7279265Sdillon#define ZIDLE_HI(v) ((v) * 4 / 5) 7379265Sdillon 7482314Speterstatic int zero_state; 7582314Speter 7682314Speterstatic int 7782314Spetervm_page_zero_check(void) 7879265Sdillon{ 7979265Sdillon 8082314Speter if (!idlezero_enable) 8182314Speter return 0; 8279265Sdillon /* 8379265Sdillon * Attempt to maintain approximately 1/2 of our free pages in a 8479265Sdillon * PG_ZERO'd state. Add some hysteresis to (attempt to) avoid 8579265Sdillon * generally zeroing a page when the system is near steady-state. 8679265Sdillon * Otherwise we might get 'flutter' during disk I/O / IPC or 8779265Sdillon * fast sleeps. We also do not want to be continuously zeroing 8879265Sdillon * pages because doing so may flush our L1 and L2 caches too much. 8979265Sdillon */ 9079265Sdillon if (zero_state && vm_page_zero_count >= ZIDLE_LO(cnt.v_free_count)) 9182314Speter return 0; 9279265Sdillon if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count)) 9382314Speter return 0; 9482314Speter return 1; 9582314Speter} 9679265Sdillon 9782314Speterstatic int 9882314Spetervm_page_zero_idle(void) 9982314Speter{ 10082314Speter static int free_rover; 10182314Speter vm_page_t m; 10282314Speter 10399625Speter mtx_lock_spin(&vm_page_queue_free_mtx); 10482314Speter zero_state = 0; 10582314Speter m = vm_pageq_find(PQ_FREE, free_rover, FALSE); 10682314Speter if (m != NULL && (m->flags & PG_ZERO) == 0) { 107100193Salc vm_pageq_remove_nowakeup(m); 10899625Speter mtx_unlock_spin(&vm_page_queue_free_mtx); 10999571Speter pmap_zero_page_idle(m); 11099625Speter mtx_lock_spin(&vm_page_queue_free_mtx); 111100331Salc m->flags |= PG_ZERO; 112100193Salc vm_pageq_enqueue(PQ_FREE + m->pc, m); 11382314Speter ++vm_page_zero_count; 11482314Speter ++cnt_prezero; 11582314Speter if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count)) 11682314Speter zero_state = 1; 11782314Speter } 11882314Speter free_rover = (free_rover + PQ_PRIME2) & PQ_L2_MASK; 11999625Speter mtx_unlock_spin(&vm_page_queue_free_mtx); 12082314Speter return 1; 12182314Speter} 12282314Speter 12382314Speter 12482314Speter/* 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 thread *td; 137100379Speter struct proc *p; 13882314Speter struct rtprio rtp; 13982314Speter int pages = 0; 14099571Speter int pri; 14182314Speter 142100379Speter td = curthread; 143100379Speter p = td->td_proc; 14482314Speter rtp.prio = RTP_PRIO_MAX; 14582314Speter rtp.type = RTP_PRIO_IDLE; 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(); 154104964Sjeff if (pages > idlezero_maxrun || sched_runnable()) { 15582314Speter mtx_lock_spin(&sched_lock); 156124944Sjeff mi_switch(SW_VOL); 15782314Speter mtx_unlock_spin(&sched_lock); 15882314Speter pages = 0; 15982314Speter } 16082314Speter } else { 16199571Speter tsleep(&zero_state, pri, "pgzero", hz * 300); 16282314Speter pages = 0; 16379265Sdillon } 16479265Sdillon } 16579265Sdillon} 16679265Sdillon 167113070Sdesstatic struct proc *pagezero_proc; 168125314Sjeff 169125314Sjeffstatic void 170125314Sjeffpagezero_start(void __unused *arg) 171125314Sjeff{ 172125314Sjeff int error; 173125314Sjeff 174125314Sjeff error = kthread_create(vm_pagezero, NULL, &pagezero_proc, RFSTOPPED, 0, 175125314Sjeff "pagezero"); 176125314Sjeff if (error) 177125314Sjeff panic("pagezero_start: error %d\n", error); 178125314Sjeff /* 179125314Sjeff * We're an idle task, don't count us in the load. 180125314Sjeff */ 181125314Sjeff PROC_LOCK(pagezero_proc); 182125314Sjeff pagezero_proc->p_flag |= P_NOLOAD; 183125314Sjeff PROC_UNLOCK(pagezero_proc); 184125314Sjeff mtx_lock_spin(&sched_lock); 185125314Sjeff setrunqueue(FIRST_THREAD_IN_PROC(pagezero_proc)); 186125314Sjeff mtx_unlock_spin(&sched_lock); 187125314Sjeff} 188125314SjeffSYSINIT(pagezero, SI_SUB_KTHREAD_VM, SI_ORDER_ANY, pagezero_start, NULL) 189