freebsd-dev/sys/vm/vm_zeroidle.c
Jeff Roberson 8df78c41d6 - Make SCHED_STATS more generic by adding a wrapper to create the
variables and sysctl nodes.
 - In reset walk the children of kern_sched_stats and reset the counters
   via the oid_arg1 pointer.  This allows us to add arbitrary counters to
   the tree and still reset them properly.
 - Define a set of switch types to be passed with flags to mi_switch().
   These types are named SWT_*.  These types correspond to SCHED_STATS
   counters and are automatically handled in this way.
 - Make the new SWT_ types more specific than the older switch stats.
   There are now stats for idle switches, remote idle wakeups, remote
   preemption ithreads idling, etc.
 - Add switch statistics for ULE's pickcpu algorithm.  These stats include
   how much migration there is, how often affinity was successful, how
   often threads were migrated to the local cpu on wakeup, etc.

Sponsored by:	Nokia
2008-04-17 04:20:10 +00:00

168 lines
4.7 KiB
C

/*-
* Copyright (c) 1994 John Dyson
* Copyright (c) 2001 Matt Dillon
*
* All Rights Reserved.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* from: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91
* Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
* from: FreeBSD: .../i386/vm_machdep.c,v 1.165 2001/07/04 23:27:04 dillon
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <opt_sched.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/vmmeter.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sched.h>
#include <sys/sysctl.h>
#include <sys/kthread.h>
#include <sys/unistd.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_phys.h>
static int idlezero_enable_default = 0;
TUNABLE_INT("vm.idlezero_enable", &idlezero_enable_default);
/* Defer setting the enable flag until the kthread is running. */
static int idlezero_enable = 0;
SYSCTL_INT(_vm, OID_AUTO, idlezero_enable, CTLFLAG_RW, &idlezero_enable, 0, "");
/*
* Implement the pre-zeroed page mechanism.
*/
#define ZIDLE_LO(v) ((v) * 2 / 3)
#define ZIDLE_HI(v) ((v) * 4 / 5)
static boolean_t wakeup_needed = FALSE;
static int zero_state;
static int
vm_page_zero_check(void)
{
if (!idlezero_enable)
return (0);
/*
* Attempt to maintain approximately 1/2 of our free pages in a
* PG_ZERO'd state. Add some hysteresis to (attempt to) avoid
* generally zeroing a page when the system is near steady-state.
* Otherwise we might get 'flutter' during disk I/O / IPC or
* fast sleeps. We also do not want to be continuously zeroing
* pages because doing so may flush our L1 and L2 caches too much.
*/
if (zero_state && vm_page_zero_count >= ZIDLE_LO(cnt.v_free_count))
return (0);
if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count))
return (0);
return (1);
}
static void
vm_page_zero_idle(void)
{
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
zero_state = 0;
if (vm_phys_zero_pages_idle()) {
if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count))
zero_state = 1;
}
}
/* Called by vm_page_free to hint that a new page is available. */
void
vm_page_zero_idle_wakeup(void)
{
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
if (wakeup_needed && vm_page_zero_check()) {
wakeup_needed = FALSE;
wakeup(&zero_state);
}
}
static void
vm_pagezero(void __unused *arg)
{
idlezero_enable = idlezero_enable_default;
mtx_lock(&vm_page_queue_free_mtx);
for (;;) {
if (vm_page_zero_check()) {
vm_page_zero_idle();
#ifndef PREEMPTION
if (sched_runnable()) {
thread_lock(curthread);
mi_switch(SW_VOL | SWT_IDLE, NULL);
thread_unlock(curthread);
}
#endif
} else {
wakeup_needed = TRUE;
msleep(&zero_state, &vm_page_queue_free_mtx, 0,
"pgzero", hz * 300);
}
}
}
static struct proc *pagezero_proc;
static void
pagezero_start(void __unused *arg)
{
int error;
struct thread *td;
error = kproc_create(vm_pagezero, NULL, &pagezero_proc, RFSTOPPED, 0,
"pagezero");
if (error)
panic("pagezero_start: error %d\n", error);
/*
* We're an idle task, don't count us in the load.
*/
PROC_LOCK(pagezero_proc);
pagezero_proc->p_flag |= P_NOLOAD;
PROC_UNLOCK(pagezero_proc);
td = FIRST_THREAD_IN_PROC(pagezero_proc);
thread_lock(td);
sched_class(td, PRI_IDLE);
sched_prio(td, PRI_MAX_IDLE);
sched_add(td, SRQ_BORING);
thread_unlock(td);
}
SYSINIT(pagezero, SI_SUB_KTHREAD_VM, SI_ORDER_ANY, pagezero_start, NULL);