freebsd-src/sys/vm/phys_pager.c
Matthew Dillon 8b03c8ed5e This is a cleanup patch to Peter's new OBJT_PHYS VM object type
and sysv shared memory support for it.  It implements a new
    PG_UNMANAGED flag that has slightly different characteristics
    from PG_FICTICIOUS.

    A new sysctl, kern.ipc.shm_use_phys has been added to enable the
    use of physically-backed sysv shared memory rather then swap-backed.
    Physically backed shm segments are not tracked with PV entries,
    allowing programs which use a large shm segment as a rendezvous
    point to operate without eating an insane amount of KVM in the
    PV entry management.  Read: Oracle.

    Peter's OBJT_PHYS object will also allow us to eventually implement
    page-table sharing and/or 4MB physical page support for such segments.
    We're half way there.
2000-05-29 22:40:54 +00:00

208 lines
5.2 KiB
C

/*
* Copyright (c) 2000 Peter Wemm
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``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 AUTHORS OR CONTRIBUTORS 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.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/linker_set.h>
#include <sys/conf.h>
#include <sys/mman.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vm_zone.h>
static void phys_pager_init __P((void));
static vm_object_t phys_pager_alloc __P((void *, vm_ooffset_t, vm_prot_t,
vm_ooffset_t));
static void phys_pager_dealloc __P((vm_object_t));
static int phys_pager_getpages __P((vm_object_t, vm_page_t *, int, int));
static void phys_pager_putpages __P((vm_object_t, vm_page_t *, int,
boolean_t, int *));
static boolean_t phys_pager_haspage __P((vm_object_t, vm_pindex_t, int *,
int *));
/* list of device pager objects */
static struct pagerlst phys_pager_object_list;
static int phys_pager_alloc_lock, phys_pager_alloc_lock_want;
struct pagerops physpagerops = {
phys_pager_init,
phys_pager_alloc,
phys_pager_dealloc,
phys_pager_getpages,
phys_pager_putpages,
phys_pager_haspage,
NULL
};
static void
phys_pager_init()
{
TAILQ_INIT(&phys_pager_object_list);
}
static vm_object_t
phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff)
{
vm_object_t object;
/*
* Offset should be page aligned.
*/
if (foff & PAGE_MASK)
return (NULL);
size = round_page(size);
/*
* Lock to prevent object creation race condition.
*/
while (phys_pager_alloc_lock) {
phys_pager_alloc_lock_want++;
tsleep(&phys_pager_alloc_lock, PVM, "ppall", 0);
phys_pager_alloc_lock_want--;
}
phys_pager_alloc_lock = 1;
/*
* Look up pager, creating as necessary.
*/
object = vm_pager_object_lookup(&phys_pager_object_list, handle);
if (object == NULL) {
/*
* Allocate object and associate it with the pager.
*/
object = vm_object_allocate(OBJT_PHYS,
OFF_TO_IDX(foff + size));
object->handle = handle;
#if 0
TAILQ_INIT(&object->un_pager.physp.physp_pglist);
#endif
TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
pager_object_list);
} else {
/*
* Gain a reference to the object.
*/
vm_object_reference(object);
if (OFF_TO_IDX(foff + size) > object->size)
object->size = OFF_TO_IDX(foff + size);
}
phys_pager_alloc_lock = 0;
if (phys_pager_alloc_lock_want)
wakeup(&phys_pager_alloc_lock);
return (object);
}
static void
phys_pager_dealloc(object)
vm_object_t object;
{
vm_page_t m;
int s;
TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
}
static int
phys_pager_getpages(object, m, count, reqpage)
vm_object_t object;
vm_page_t *m;
int count;
int reqpage;
{
int i, s;
s = splvm();
/*
* Fill as many pages as vm_fault has allocated for us.
*/
for (i = 0; i < count; i++) {
if ((m[i]->flags & PG_ZERO) == 0)
vm_page_zero_fill(m[i]);
vm_page_flag_set(m[i], PG_ZERO);
/* Switch off pv_entries */
vm_page_unmanage(m[i]);
m[i]->valid = VM_PAGE_BITS_ALL;
m[i]->dirty = 0;
/* The requested page must remain busy, the others not. */
if (reqpage != i) {
vm_page_flag_clear(m[i], PG_BUSY);
m[i]->busy = 0;
}
}
splx(s);
return (VM_PAGER_OK);
}
static void
phys_pager_putpages(object, m, count, sync, rtvals)
vm_object_t object;
vm_page_t *m;
int count;
boolean_t sync;
int *rtvals;
{
panic("phys_pager_putpage called");
}
/*
* Implement a pretty aggressive clustered getpages strategy. Hint that
* everything in an entire 4MB window should be prefaulted at once.
*
* XXX 4MB (1024 slots per page table page) is convenient for x86,
* but may not be for other arches.
*/
#ifndef PHYSCLUSTER
#define PHYSCLUSTER 1024
#endif
static boolean_t
phys_pager_haspage(object, pindex, before, after)
vm_object_t object;
vm_pindex_t pindex;
int *before;
int *after;
{
vm_pindex_t base, end;
base = pindex & (~(PHYSCLUSTER - 1));
end = base + (PHYSCLUSTER - 1);
if (before != NULL)
*before = pindex - base;
if (after != NULL)
*after = end - pindex;
return (TRUE);
}