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8b03c8ed5e
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.
208 lines
5.2 KiB
C
208 lines
5.2 KiB
C
/*
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* Copyright (c) 2000 Peter Wemm
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/linker_set.h>
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#include <sys/conf.h>
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#include <sys/mman.h>
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#include <sys/sysctl.h>
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#include <vm/vm.h>
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#include <vm/vm_object.h>
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#include <vm/vm_page.h>
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#include <vm/vm_pager.h>
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#include <vm/vm_zone.h>
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static void phys_pager_init __P((void));
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static vm_object_t phys_pager_alloc __P((void *, vm_ooffset_t, vm_prot_t,
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vm_ooffset_t));
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static void phys_pager_dealloc __P((vm_object_t));
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static int phys_pager_getpages __P((vm_object_t, vm_page_t *, int, int));
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static void phys_pager_putpages __P((vm_object_t, vm_page_t *, int,
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boolean_t, int *));
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static boolean_t phys_pager_haspage __P((vm_object_t, vm_pindex_t, int *,
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int *));
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/* list of device pager objects */
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static struct pagerlst phys_pager_object_list;
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static int phys_pager_alloc_lock, phys_pager_alloc_lock_want;
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struct pagerops physpagerops = {
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phys_pager_init,
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phys_pager_alloc,
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phys_pager_dealloc,
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phys_pager_getpages,
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phys_pager_putpages,
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phys_pager_haspage,
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NULL
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};
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static void
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phys_pager_init()
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{
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TAILQ_INIT(&phys_pager_object_list);
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}
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static vm_object_t
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phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
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vm_ooffset_t foff)
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{
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vm_object_t object;
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/*
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* Offset should be page aligned.
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*/
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if (foff & PAGE_MASK)
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return (NULL);
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size = round_page(size);
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/*
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* Lock to prevent object creation race condition.
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*/
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while (phys_pager_alloc_lock) {
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phys_pager_alloc_lock_want++;
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tsleep(&phys_pager_alloc_lock, PVM, "ppall", 0);
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phys_pager_alloc_lock_want--;
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}
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phys_pager_alloc_lock = 1;
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/*
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* Look up pager, creating as necessary.
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*/
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object = vm_pager_object_lookup(&phys_pager_object_list, handle);
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if (object == NULL) {
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/*
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* Allocate object and associate it with the pager.
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*/
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object = vm_object_allocate(OBJT_PHYS,
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OFF_TO_IDX(foff + size));
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object->handle = handle;
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#if 0
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TAILQ_INIT(&object->un_pager.physp.physp_pglist);
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#endif
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TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
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pager_object_list);
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} else {
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/*
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* Gain a reference to the object.
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*/
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vm_object_reference(object);
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if (OFF_TO_IDX(foff + size) > object->size)
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object->size = OFF_TO_IDX(foff + size);
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}
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phys_pager_alloc_lock = 0;
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if (phys_pager_alloc_lock_want)
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wakeup(&phys_pager_alloc_lock);
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return (object);
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}
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static void
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phys_pager_dealloc(object)
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vm_object_t object;
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{
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vm_page_t m;
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int s;
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TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
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}
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static int
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phys_pager_getpages(object, m, count, reqpage)
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vm_object_t object;
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vm_page_t *m;
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int count;
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int reqpage;
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{
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int i, s;
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s = splvm();
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/*
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* Fill as many pages as vm_fault has allocated for us.
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*/
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for (i = 0; i < count; i++) {
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if ((m[i]->flags & PG_ZERO) == 0)
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vm_page_zero_fill(m[i]);
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vm_page_flag_set(m[i], PG_ZERO);
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/* Switch off pv_entries */
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vm_page_unmanage(m[i]);
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m[i]->valid = VM_PAGE_BITS_ALL;
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m[i]->dirty = 0;
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/* The requested page must remain busy, the others not. */
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if (reqpage != i) {
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vm_page_flag_clear(m[i], PG_BUSY);
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m[i]->busy = 0;
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}
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}
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splx(s);
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return (VM_PAGER_OK);
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}
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static void
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phys_pager_putpages(object, m, count, sync, rtvals)
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vm_object_t object;
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vm_page_t *m;
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int count;
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boolean_t sync;
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int *rtvals;
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{
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panic("phys_pager_putpage called");
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}
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/*
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* Implement a pretty aggressive clustered getpages strategy. Hint that
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* everything in an entire 4MB window should be prefaulted at once.
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*
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* XXX 4MB (1024 slots per page table page) is convenient for x86,
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* but may not be for other arches.
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*/
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#ifndef PHYSCLUSTER
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#define PHYSCLUSTER 1024
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#endif
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static boolean_t
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phys_pager_haspage(object, pindex, before, after)
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vm_object_t object;
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vm_pindex_t pindex;
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int *before;
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int *after;
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{
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vm_pindex_t base, end;
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base = pindex & (~(PHYSCLUSTER - 1));
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end = base + (PHYSCLUSTER - 1);
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if (before != NULL)
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*before = pindex - base;
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if (after != NULL)
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*after = end - pindex;
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return (TRUE);
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}
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