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freebsd/sys/vm/vm_kern.c
Konstantin Belousov ee75e7de7b Implement the concept of the unmapped VMIO buffers, i.e. buffers which 
do not map the b_pages pages into buffer_map KVA.  The use of the
unmapped buffers eliminate the need to perform TLB shootdown for
mapping on the buffer creation and reuse, greatly reducing the amount
of IPIs for shootdown on big-SMP machines and eliminating up to 25-30%
of the system time on i/o intensive workloads.

The unmapped buffer should be explicitely requested by the GB_UNMAPPED
flag by the consumer.  For unmapped buffer, no KVA reservation is
performed at all. The consumer might request unmapped buffer which
does have a KVA reserve, to manually map it without recursing into
buffer cache and blocking, with the GB_KVAALLOC flag.

When the mapped buffer is requested and unmapped buffer already
exists, the cache performs an upgrade, possibly reusing the KVA
reservation.

Unmapped buffer is translated into unmapped bio in g_vfs_strategy().
Unmapped bio carry a pointer to the vm_page_t array, offset and length
instead of the data pointer.  The provider which processes the bio
should explicitely specify a readiness to accept unmapped bio,
otherwise g_down geom thread performs the transient upgrade of the bio
request by mapping the pages into the new bio_transient_map KVA
submap.

The bio_transient_map submap claims up to 10% of the buffer map, and
the total buffer_map + bio_transient_map KVA usage stays the
same. Still, it could be manually tuned by kern.bio_transient_maxcnt
tunable, in the units of the transient mappings.  Eventually, the
bio_transient_map could be removed after all geom classes and drivers
can accept unmapped i/o requests.

Unmapped support can be turned off by the vfs.unmapped_buf_allowed
tunable, disabling which makes the buffer (or cluster) creation
requests to ignore GB_UNMAPPED and GB_KVAALLOC flags.  Unmapped
buffers are only enabled by default on the architectures where
pmap_copy_page() was implemented and tested.

In the rework, filesystem metadata is not the subject to maxbufspace
limit anymore. Since the metadata buffers are always mapped, the
buffers still have to fit into the buffer map, which provides a
reasonable (but practically unreachable) upper bound on it. The
non-metadata buffer allocations, both mapped and unmapped, is
accounted against maxbufspace, as before. Effectively, this means that
the maxbufspace is forced on mapped and unmapped buffers separately.
The pre-patch bufspace limiting code did not worked, because
buffer_map fragmentation does not allow the limit to be reached.

By Jeff Roberson request, the getnewbuf() function was split into
smaller single-purpose functions.

Sponsored by:	The FreeBSD Foundation
Discussed with:	jeff (previous version)
Tested by:	pho, scottl (previous version), jhb, bf
MFC after:	2 weeks
2013-03-19 14:13:12 +00:00

719 lines
20 KiB
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Raw Blame History

/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* 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 REGENTS 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 REGENTS 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.
*
* from: @(#)vm_kern.c 8.3 (Berkeley) 1/12/94
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* Authors: Avadis Tevanian, Jr., Michael Wayne Young
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*
* Kernel memory management.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h> /* for ticks and hz */
#include <sys/eventhandler.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/rwlock.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_extern.h>
#include <vm/uma.h>
vm_map_t kernel_map;
vm_map_t kmem_map;
vm_map_t exec_map;
vm_map_t pipe_map;
vm_map_t buffer_map;
vm_map_t bio_transient_map;
const void *zero_region;
CTASSERT((ZERO_REGION_SIZE & PAGE_MASK) == 0);
SYSCTL_ULONG(_vm, OID_AUTO, min_kernel_address, CTLFLAG_RD,
NULL, VM_MIN_KERNEL_ADDRESS, "Min kernel address");
SYSCTL_ULONG(_vm, OID_AUTO, max_kernel_address, CTLFLAG_RD,
#if defined(__arm__) || defined(__sparc64__)
&vm_max_kernel_address, 0,
#else
NULL, VM_MAX_KERNEL_ADDRESS,
#endif
"Max kernel address");
/*
* kmem_alloc_nofault:
*
* Allocate a virtual address range with no underlying object and
* no initial mapping to physical memory. Any mapping from this
* range to physical memory must be explicitly created prior to
* its use, typically with pmap_qenter(). Any attempt to create
* a mapping on demand through vm_fault() will result in a panic.
*/
vm_offset_t
kmem_alloc_nofault(map, size)
vm_map_t map;
vm_size_t size;
{
vm_offset_t addr;
int result;
size = round_page(size);
addr = vm_map_min(map);
result = vm_map_find(map, NULL, 0, &addr, size, VMFS_ANY_SPACE,
VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
if (result != KERN_SUCCESS) {
return (0);
}
return (addr);
}
/*
* kmem_alloc_nofault_space:
*
* Allocate a virtual address range with no underlying object and
* no initial mapping to physical memory within the specified
* address space. Any mapping from this range to physical memory
* must be explicitly created prior to its use, typically with
* pmap_qenter(). Any attempt to create a mapping on demand
* through vm_fault() will result in a panic.
*/
vm_offset_t
kmem_alloc_nofault_space(map, size, find_space)
vm_map_t map;
vm_size_t size;
int find_space;
{
vm_offset_t addr;
int result;
size = round_page(size);
addr = vm_map_min(map);
result = vm_map_find(map, NULL, 0, &addr, size, find_space,
VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
if (result != KERN_SUCCESS) {
return (0);
}
return (addr);
}
/*
* Allocate wired-down memory in the kernel's address map
* or a submap.
*/
vm_offset_t
kmem_alloc(map, size)
vm_map_t map;
vm_size_t size;
{
vm_offset_t addr;
vm_offset_t offset;
size = round_page(size);
/*
* Use the kernel object for wired-down kernel pages. Assume that no
* region of the kernel object is referenced more than once.
*/
/*
* Locate sufficient space in the map. This will give us the final
* virtual address for the new memory, and thus will tell us the
* offset within the kernel map.
*/
vm_map_lock(map);
if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
vm_map_unlock(map);
return (0);
}
offset = addr - VM_MIN_KERNEL_ADDRESS;
vm_object_reference(kernel_object);
vm_map_insert(map, kernel_object, offset, addr, addr + size,
VM_PROT_ALL, VM_PROT_ALL, 0);
vm_map_unlock(map);
/*
* And finally, mark the data as non-pageable.
*/
(void) vm_map_wire(map, addr, addr + size,
VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
return (addr);
}
/*
* Allocates a region from the kernel address map and physical pages
* within the specified address range to the kernel object. Creates a
* wired mapping from this region to these pages, and returns the
* region's starting virtual address. The allocated pages are not
* necessarily physically contiguous. If M_ZERO is specified through the
* given flags, then the pages are zeroed before they are mapped.
*/
vm_offset_t
kmem_alloc_attr(vm_map_t map, vm_size_t size, int flags, vm_paddr_t low,
vm_paddr_t high, vm_memattr_t memattr)
{
vm_object_t object = kernel_object;
vm_offset_t addr;
vm_ooffset_t end_offset, offset;
vm_page_t m;
int pflags, tries;
size = round_page(size);
vm_map_lock(map);
if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
vm_map_unlock(map);
return (0);
}
offset = addr - VM_MIN_KERNEL_ADDRESS;
vm_object_reference(object);
vm_map_insert(map, object, offset, addr, addr + size, VM_PROT_ALL,
VM_PROT_ALL, 0);
pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY;
VM_OBJECT_WLOCK(object);
end_offset = offset + size;
for (; offset < end_offset; offset += PAGE_SIZE) {
tries = 0;
retry:
m = vm_page_alloc_contig(object, OFF_TO_IDX(offset), pflags, 1,
low, high, PAGE_SIZE, 0, memattr);
if (m == NULL) {
VM_OBJECT_WUNLOCK(object);
if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) {
vm_map_unlock(map);
vm_pageout_grow_cache(tries, low, high);
vm_map_lock(map);
VM_OBJECT_WLOCK(object);
tries++;
goto retry;
}
/*
* Since the pages that were allocated by any previous
* iterations of this loop are not busy, they can be
* freed by vm_object_page_remove(), which is called
* by vm_map_delete().
*/
vm_map_delete(map, addr, addr + size);
vm_map_unlock(map);
return (0);
}
if ((flags & M_ZERO) && (m->flags & PG_ZERO) == 0)
pmap_zero_page(m);
m->valid = VM_PAGE_BITS_ALL;
}
VM_OBJECT_WUNLOCK(object);
vm_map_unlock(map);
vm_map_wire(map, addr, addr + size, VM_MAP_WIRE_SYSTEM |
VM_MAP_WIRE_NOHOLES);
return (addr);
}
/*
* Allocates a region from the kernel address map and physically
* contiguous pages within the specified address range to the kernel
* object. Creates a wired mapping from this region to these pages, and
* returns the region's starting virtual address. If M_ZERO is specified
* through the given flags, then the pages are zeroed before they are
* mapped.
*/
vm_offset_t
kmem_alloc_contig(vm_map_t map, vm_size_t size, int flags, vm_paddr_t low,
vm_paddr_t high, u_long alignment, vm_paddr_t boundary,
vm_memattr_t memattr)
{
vm_object_t object = kernel_object;
vm_offset_t addr;
vm_ooffset_t offset;
vm_page_t end_m, m;
int pflags, tries;
size = round_page(size);
vm_map_lock(map);
if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
vm_map_unlock(map);
return (0);
}
offset = addr - VM_MIN_KERNEL_ADDRESS;
vm_object_reference(object);
vm_map_insert(map, object, offset, addr, addr + size, VM_PROT_ALL,
VM_PROT_ALL, 0);
pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY;
VM_OBJECT_WLOCK(object);
tries = 0;
retry:
m = vm_page_alloc_contig(object, OFF_TO_IDX(offset), pflags,
atop(size), low, high, alignment, boundary, memattr);
if (m == NULL) {
VM_OBJECT_WUNLOCK(object);
if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) {
vm_map_unlock(map);
vm_pageout_grow_cache(tries, low, high);
vm_map_lock(map);
VM_OBJECT_WLOCK(object);
tries++;
goto retry;
}
vm_map_delete(map, addr, addr + size);
vm_map_unlock(map);
return (0);
}
end_m = m + atop(size);
for (; m < end_m; m++) {
if ((flags & M_ZERO) && (m->flags & PG_ZERO) == 0)
pmap_zero_page(m);
m->valid = VM_PAGE_BITS_ALL;
}
VM_OBJECT_WUNLOCK(object);
vm_map_unlock(map);
vm_map_wire(map, addr, addr + size, VM_MAP_WIRE_SYSTEM |
VM_MAP_WIRE_NOHOLES);
return (addr);
}
/*
* kmem_free:
*
* Release a region of kernel virtual memory allocated
* with kmem_alloc, and return the physical pages
* associated with that region.
*
* This routine may not block on kernel maps.
*/
void
kmem_free(map, addr, size)
vm_map_t map;
vm_offset_t addr;
vm_size_t size;
{
(void) vm_map_remove(map, trunc_page(addr), round_page(addr + size));
}
/*
* kmem_suballoc:
*
* Allocates a map to manage a subrange
* of the kernel virtual address space.
*
* Arguments are as follows:
*
* parent Map to take range from
* min, max Returned endpoints of map
* size Size of range to find
* superpage_align Request that min is superpage aligned
*/
vm_map_t
kmem_suballoc(vm_map_t parent, vm_offset_t *min, vm_offset_t *max,
vm_size_t size, boolean_t superpage_align)
{
int ret;
vm_map_t result;
size = round_page(size);
*min = vm_map_min(parent);
ret = vm_map_find(parent, NULL, 0, min, size, superpage_align ?
VMFS_ALIGNED_SPACE : VMFS_ANY_SPACE, VM_PROT_ALL, VM_PROT_ALL,
MAP_ACC_NO_CHARGE);
if (ret != KERN_SUCCESS)
panic("kmem_suballoc: bad status return of %d", ret);
*max = *min + size;
result = vm_map_create(vm_map_pmap(parent), *min, *max);
if (result == NULL)
panic("kmem_suballoc: cannot create submap");
if (vm_map_submap(parent, *min, *max, result) != KERN_SUCCESS)
panic("kmem_suballoc: unable to change range to submap");
return (result);
}
/*
* kmem_malloc:
*
* Allocate wired-down memory in the kernel's address map for the higher
* level kernel memory allocator (kern/kern_malloc.c). We cannot use
* kmem_alloc() because we may need to allocate memory at interrupt
* level where we cannot block (canwait == FALSE).
*
* This routine has its own private kernel submap (kmem_map) and object
* (kmem_object). This, combined with the fact that only malloc uses
* this routine, ensures that we will never block in map or object waits.
*
* We don't worry about expanding the map (adding entries) since entries
* for wired maps are statically allocated.
*
* `map' is ONLY allowed to be kmem_map or one of the mbuf submaps to
* which we never free.
*/
vm_offset_t
kmem_malloc(map, size, flags)
vm_map_t map;
vm_size_t size;
int flags;
{
vm_offset_t addr;
int i, rv;
size = round_page(size);
addr = vm_map_min(map);
/*
* Locate sufficient space in the map. This will give us the final
* virtual address for the new memory, and thus will tell us the
* offset within the kernel map.
*/
vm_map_lock(map);
if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
vm_map_unlock(map);
if ((flags & M_NOWAIT) == 0) {
for (i = 0; i < 8; i++) {
EVENTHANDLER_INVOKE(vm_lowmem, 0);
uma_reclaim();
vm_map_lock(map);
if (vm_map_findspace(map, vm_map_min(map),
size, &addr) == 0) {
break;
}
vm_map_unlock(map);
tsleep(&i, 0, "nokva", (hz / 4) * (i + 1));
}
if (i == 8) {
panic("kmem_malloc(%ld): kmem_map too small: %ld total allocated",
(long)size, (long)map->size);
}
} else {
return (0);
}
}
rv = kmem_back(map, addr, size, flags);
vm_map_unlock(map);
return (rv == KERN_SUCCESS ? addr : 0);
}
/*
* kmem_back:
*
* Allocate physical pages for the specified virtual address range.
*/
int
kmem_back(vm_map_t map, vm_offset_t addr, vm_size_t size, int flags)
{
vm_offset_t offset, i;
vm_map_entry_t entry;
vm_page_t m;
int pflags;
boolean_t found;
KASSERT(vm_map_locked(map), ("kmem_back: map %p is not locked", map));
offset = addr - VM_MIN_KERNEL_ADDRESS;
vm_object_reference(kmem_object);
vm_map_insert(map, kmem_object, offset, addr, addr + size,
VM_PROT_ALL, VM_PROT_ALL, 0);
/*
* Assert: vm_map_insert() will never be able to extend the
* previous entry so vm_map_lookup_entry() will find a new
* entry exactly corresponding to this address range and it
* will have wired_count == 0.
*/
found = vm_map_lookup_entry(map, addr, &entry);
KASSERT(found && entry->start == addr && entry->end == addr + size &&
entry->wired_count == 0 && (entry->eflags & MAP_ENTRY_IN_TRANSITION)
== 0, ("kmem_back: entry not found or misaligned"));
pflags = malloc2vm_flags(flags) | VM_ALLOC_WIRED;
VM_OBJECT_WLOCK(kmem_object);
for (i = 0; i < size; i += PAGE_SIZE) {
retry:
m = vm_page_alloc(kmem_object, OFF_TO_IDX(offset + i), pflags);
/*
* Ran out of space, free everything up and return. Don't need
* to lock page queues here as we know that the pages we got
* aren't on any queues.
*/
if (m == NULL) {
if ((flags & M_NOWAIT) == 0) {
VM_OBJECT_WUNLOCK(kmem_object);
entry->eflags |= MAP_ENTRY_IN_TRANSITION;
vm_map_unlock(map);
VM_WAIT;
vm_map_lock(map);
KASSERT(
(entry->eflags & (MAP_ENTRY_IN_TRANSITION | MAP_ENTRY_NEEDS_WAKEUP)) ==
MAP_ENTRY_IN_TRANSITION,
("kmem_back: volatile entry"));
entry->eflags &= ~MAP_ENTRY_IN_TRANSITION;
VM_OBJECT_WLOCK(kmem_object);
goto retry;
}
/*
* Free the pages before removing the map entry.
* They are already marked busy. Calling
* vm_map_delete before the pages has been freed or
* unbusied will cause a deadlock.
*/
while (i != 0) {
i -= PAGE_SIZE;
m = vm_page_lookup(kmem_object,
OFF_TO_IDX(offset + i));
vm_page_unwire(m, 0);
vm_page_free(m);
}
VM_OBJECT_WUNLOCK(kmem_object);
vm_map_delete(map, addr, addr + size);
return (KERN_NO_SPACE);
}
if (flags & M_ZERO && (m->flags & PG_ZERO) == 0)
pmap_zero_page(m);
m->valid = VM_PAGE_BITS_ALL;
KASSERT((m->oflags & VPO_UNMANAGED) != 0,
("kmem_malloc: page %p is managed", m));
}
VM_OBJECT_WUNLOCK(kmem_object);
/*
* Mark map entry as non-pageable. Repeat the assert.
*/
KASSERT(entry->start == addr && entry->end == addr + size &&
entry->wired_count == 0,
("kmem_back: entry not found or misaligned after allocation"));
entry->wired_count = 1;
/*
* At this point, the kmem_object must be unlocked because
* vm_map_simplify_entry() calls vm_object_deallocate(), which
* locks the kmem_object.
*/
vm_map_simplify_entry(map, entry);
/*
* Loop thru pages, entering them in the pmap.
*/
VM_OBJECT_WLOCK(kmem_object);
for (i = 0; i < size; i += PAGE_SIZE) {
m = vm_page_lookup(kmem_object, OFF_TO_IDX(offset + i));
/*
* Because this is kernel_pmap, this call will not block.
*/
pmap_enter(kernel_pmap, addr + i, VM_PROT_ALL, m, VM_PROT_ALL,
TRUE);
vm_page_wakeup(m);
}
VM_OBJECT_WUNLOCK(kmem_object);
return (KERN_SUCCESS);
}
/*
* kmem_alloc_wait:
*
* Allocates pageable memory from a sub-map of the kernel. If the submap
* has no room, the caller sleeps waiting for more memory in the submap.
*
* This routine may block.
*/
vm_offset_t
kmem_alloc_wait(map, size)
vm_map_t map;
vm_size_t size;
{
vm_offset_t addr;
size = round_page(size);
if (!swap_reserve(size))
return (0);
for (;;) {
/*
* To make this work for more than one map, use the map's lock
* to lock out sleepers/wakers.
*/
vm_map_lock(map);
if (vm_map_findspace(map, vm_map_min(map), size, &addr) == 0)
break;
/* no space now; see if we can ever get space */
if (vm_map_max(map) - vm_map_min(map) < size) {
vm_map_unlock(map);
swap_release(size);
return (0);
}
map->needs_wakeup = TRUE;
vm_map_unlock_and_wait(map, 0);
}
vm_map_insert(map, NULL, 0, addr, addr + size, VM_PROT_ALL,
VM_PROT_ALL, MAP_ACC_CHARGED);
vm_map_unlock(map);
return (addr);
}
/*
* kmem_free_wakeup:
*
* Returns memory to a submap of the kernel, and wakes up any processes
* waiting for memory in that map.
*/
void
kmem_free_wakeup(map, addr, size)
vm_map_t map;
vm_offset_t addr;
vm_size_t size;
{
vm_map_lock(map);
(void) vm_map_delete(map, trunc_page(addr), round_page(addr + size));
if (map->needs_wakeup) {
map->needs_wakeup = FALSE;
vm_map_wakeup(map);
}
vm_map_unlock(map);
}
static void
kmem_init_zero_region(void)
{
vm_offset_t addr, i;
vm_page_t m;
int error;
/*
* Map a single physical page of zeros to a larger virtual range.
* This requires less looping in places that want large amounts of
* zeros, while not using much more physical resources.
*/
addr = kmem_alloc_nofault(kernel_map, ZERO_REGION_SIZE);
m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
VM_ALLOC_NOOBJ | VM_ALLOC_WIRED | VM_ALLOC_ZERO);
if ((m->flags & PG_ZERO) == 0)
pmap_zero_page(m);
for (i = 0; i < ZERO_REGION_SIZE; i += PAGE_SIZE)
pmap_qenter(addr + i, &m, 1);
error = vm_map_protect(kernel_map, addr, addr + ZERO_REGION_SIZE,
VM_PROT_READ, TRUE);
KASSERT(error == 0, ("error=%d", error));
zero_region = (const void *)addr;
}
/*
* kmem_init:
*
* Create the kernel map; insert a mapping covering kernel text,
* data, bss, and all space allocated thus far (`boostrap' data). The
* new map will thus map the range between VM_MIN_KERNEL_ADDRESS and
* `start' as allocated, and the range between `start' and `end' as free.
*/
void
kmem_init(start, end)
vm_offset_t start, end;
{
vm_map_t m;
m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end);
m->system_map = 1;
vm_map_lock(m);
/* N.B.: cannot use kgdb to debug, starting with this assignment ... */
kernel_map = m;
(void) vm_map_insert(m, NULL, (vm_ooffset_t) 0,
#ifdef __amd64__
KERNBASE,
#else
VM_MIN_KERNEL_ADDRESS,
#endif
start, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
/* ... and ending with the completion of the above `insert' */
vm_map_unlock(m);
kmem_init_zero_region();
}
#ifdef DIAGNOSTIC
/*
* Allow userspace to directly trigger the VM drain routine for testing
* purposes.
*/
static int
debug_vm_lowmem(SYSCTL_HANDLER_ARGS)
{
int error, i;
i = 0;
error = sysctl_handle_int(oidp, &i, 0, req);
if (error)
return (error);
if (i)
EVENTHANDLER_INVOKE(vm_lowmem, 0);
return (0);
}
SYSCTL_PROC(_debug, OID_AUTO, vm_lowmem, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
debug_vm_lowmem, "I", "set to trigger vm_lowmem event");
#endif
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