freebsd-dev/sys/vm/vm_extern.h
Attilio Rao 3b6714cacb The page hold mechanism is fast but it has couple of fallouts:
- It does not let pages respect the LRU policy
- It bloats the active/inactive queues of few pages

Try to avoid it as much as possible with the long-term target to
completely remove it.
Use the soft-busy mechanism to protect page content accesses during
short-term operations (like uiomove_fromphys()).

After this change only vm_fault_quick_hold_pages() is still using the
hold mechanism for page content access.
There is an additional complexity there as the quick path cannot
immediately access the page object to busy the page and the slow path
cannot however busy more than one page a time (to avoid deadlocks).

Fixing such primitive can bring to complete removal of the page hold
mechanism.

Sponsored by:	EMC / Isilon storage division
Discussed with:	alc
Reviewed by:	jeff
Tested by:	pho
2013-08-04 21:07:24 +00:00

96 lines
4.4 KiB
C

/*-
* Copyright (c) 1992, 1993
* The Regents of the University of California. 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 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.
*
* @(#)vm_extern.h 8.2 (Berkeley) 1/12/94
* $FreeBSD$
*/
#ifndef _VM_EXTERN_H_
#define _VM_EXTERN_H_
struct proc;
struct vmspace;
struct vnode;
#ifdef _KERNEL
int kernacc(void *, int, int);
vm_offset_t kmem_alloc(vm_map_t, vm_size_t);
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_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_offset_t kmem_alloc_nofault(vm_map_t, vm_size_t);
vm_offset_t kmem_alloc_nofault_space(vm_map_t, vm_size_t, int);
vm_offset_t kmem_alloc_wait(vm_map_t, vm_size_t);
void kmem_free(vm_map_t, vm_offset_t, vm_size_t);
void kmem_free_wakeup(vm_map_t, vm_offset_t, vm_size_t);
void kmem_init(vm_offset_t, vm_offset_t);
vm_offset_t kmem_malloc(vm_map_t map, vm_size_t size, int flags);
int kmem_back(vm_map_t, vm_offset_t, vm_size_t, int);
vm_map_t kmem_suballoc(vm_map_t, vm_offset_t *, vm_offset_t *, vm_size_t,
boolean_t);
void swapout_procs(int);
int useracc(void *, int, int);
int vm_fault(vm_map_t, vm_offset_t, vm_prot_t, int);
void vm_fault_copy_entry(vm_map_t, vm_map_t, vm_map_entry_t, vm_map_entry_t,
vm_ooffset_t *);
int vm_fault_disable_pagefaults(void);
void vm_fault_enable_pagefaults(int save);
int vm_fault_handle(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
int fault_flags, vm_page_t *m_hold);
int vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
vm_prot_t prot, vm_page_t *ma, int max_count);
void vm_fault_unwire(vm_map_t, vm_offset_t, vm_offset_t, boolean_t);
int vm_fault_wire(vm_map_t, vm_offset_t, vm_offset_t, boolean_t);
int vm_forkproc(struct thread *, struct proc *, struct thread *, struct vmspace *, int);
void vm_waitproc(struct proc *);
int vm_mmap(vm_map_t, vm_offset_t *, vm_size_t, vm_prot_t, vm_prot_t, int, objtype_t, void *, vm_ooffset_t);
int vm_mmap_to_errno(int rv);
void vm_set_page_size(void);
void vm_sync_icache(vm_map_t, vm_offset_t, vm_size_t);
struct vmspace *vmspace_alloc(vm_offset_t, vm_offset_t);
struct vmspace *vmspace_fork(struct vmspace *, vm_ooffset_t *);
int vmspace_exec(struct proc *, vm_offset_t, vm_offset_t);
int vmspace_unshare(struct proc *);
void vmspace_exit(struct thread *);
struct vmspace *vmspace_acquire_ref(struct proc *);
void vmspace_free(struct vmspace *);
void vmspace_exitfree(struct proc *);
void vnode_pager_setsize(struct vnode *, vm_ooffset_t);
int vslock(void *, size_t);
void vsunlock(void *, size_t);
struct sf_buf *vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset);
void vm_imgact_unmap_page(vm_object_t, struct sf_buf *sf);
void vm_thread_dispose(struct thread *td);
int vm_thread_new(struct thread *td, int pages);
int vm_mlock(struct proc *, struct ucred *, const void *, size_t);
#endif /* _KERNEL */
#endif /* !_VM_EXTERN_H_ */