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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
157 lines
5.3 KiB
C
157 lines
5.3 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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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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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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* @(#)vm.h 8.2 (Berkeley) 12/13/93
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* @(#)vm_prot.h 8.1 (Berkeley) 6/11/93
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* @(#)vm_inherit.h 8.1 (Berkeley) 6/11/93
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Authors: Avadis Tevanian, Jr., Michael Wayne Young
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*
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* $FreeBSD$
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*/
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#ifndef VM_H
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#define VM_H
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#include <machine/vm.h>
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typedef char vm_inherit_t; /* inheritance codes */
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#define VM_INHERIT_SHARE ((vm_inherit_t) 0)
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#define VM_INHERIT_COPY ((vm_inherit_t) 1)
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#define VM_INHERIT_NONE ((vm_inherit_t) 2)
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#define VM_INHERIT_DEFAULT VM_INHERIT_COPY
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typedef u_char vm_prot_t; /* protection codes */
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#define VM_PROT_NONE ((vm_prot_t) 0x00)
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#define VM_PROT_READ ((vm_prot_t) 0x01)
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#define VM_PROT_WRITE ((vm_prot_t) 0x02)
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#define VM_PROT_EXECUTE ((vm_prot_t) 0x04)
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#define VM_PROT_COPY ((vm_prot_t) 0x08) /* copy-on-read */
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#define VM_PROT_ALL (VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE)
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#define VM_PROT_RW (VM_PROT_READ|VM_PROT_WRITE)
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#define VM_PROT_DEFAULT VM_PROT_ALL
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enum obj_type { OBJT_DEFAULT, OBJT_SWAP, OBJT_VNODE, OBJT_DEVICE, OBJT_PHYS,
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OBJT_DEAD, OBJT_SG, OBJT_MGTDEVICE };
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typedef u_char objtype_t;
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union vm_map_object;
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typedef union vm_map_object vm_map_object_t;
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struct vm_map_entry;
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typedef struct vm_map_entry *vm_map_entry_t;
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struct vm_map;
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typedef struct vm_map *vm_map_t;
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struct vm_object;
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typedef struct vm_object *vm_object_t;
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#ifndef _KERNEL
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/*
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* This is defined in <sys/types.h> for the kernel so that non-vm kernel
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* sources (mainly Mach-derived ones such as ddb) don't have to include
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* vm stuff. Defining it there for applications might break things.
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* Define it here for "applications" that include vm headers (e.g.,
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* genassym).
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*/
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typedef int boolean_t;
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/*
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* The exact set of memory attributes is machine dependent. However, every
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* machine is required to define VM_MEMATTR_DEFAULT.
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*/
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typedef char vm_memattr_t; /* memory attribute codes */
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/*
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* This is defined in <sys/types.h> for the kernel so that vnode_if.h
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* doesn't have to include <vm/vm.h>.
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*/
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struct vm_page;
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typedef struct vm_page *vm_page_t;
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#endif /* _KERNEL */
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struct vm_reserv;
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typedef struct vm_reserv *vm_reserv_t;
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/*
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* Information passed from the machine-independant VM initialization code
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* for use by machine-dependant code (mainly for MMU support)
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*/
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struct kva_md_info {
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vm_offset_t buffer_sva;
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vm_offset_t buffer_eva;
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vm_offset_t clean_sva;
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vm_offset_t clean_eva;
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vm_offset_t pager_sva;
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vm_offset_t pager_eva;
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vm_offset_t bio_transient_sva;
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vm_offset_t bio_transient_eva;
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};
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extern struct kva_md_info kmi;
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extern void vm_ksubmap_init(struct kva_md_info *);
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extern int old_mlock;
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struct ucred;
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int swap_reserve(vm_ooffset_t incr);
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int swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred);
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void swap_reserve_force(vm_ooffset_t incr);
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void swap_release(vm_ooffset_t decr);
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void swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred);
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#endif /* VM_H */
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