1/* $NetBSD: uvm_pglist.h,v 1.11 2020/04/13 15:16:14 ad Exp $ */
2
3/*-
4 * Copyright (c) 2000, 2001, 2008, 2019 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe, and by Andrew Doran.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#ifndef _UVM_UVM_PGLIST_H_
33#define _UVM_UVM_PGLIST_H_
34
35#include <sys/param.h>
36
37/*
38 * This defines the type of a page queue, e.g. active list, inactive
39 * list, etc.
40 */
41struct vm_page;
42TAILQ_HEAD(pglist, vm_page);
43LIST_HEAD(pgflist, vm_page);
44
45/*
46 * The global uvm.page_free list (uvm_page.c, uvm_pglist.c). Free pages are
47 * stored according to freelist, bucket, and cache colour.
48 *
49 * pglist = &uvm.page_free[freelist].pgfl_buckets[bucket].pgb_color[color];
50 *
51 * Freelists provide a priority ordering of pages for allocation, based upon
52 * how valuable they are for special uses (e.g. device driver DMA). MD
53 * code decides the number and structure of these. They are always arranged
54 * in descending order of allocation priority.
55 *
56 * Pages are then grouped in buckets according to some common factor, for
57 * example L2/L3 cache locality. Each bucket has its own lock, and the
58 * locks are shared among freelists for the same numbered buckets.
59 *
60 * Inside each bucket, pages are further distributed by cache color.
61 *
62 * We want these data structures to occupy as few cache lines as possible,
63 * as they will be highly contended.
64 */
65struct pgflbucket {
66 uintptr_t pgb_nfree; /* total # free pages, all colors */
67 struct pgflist pgb_colors[1]; /* variable size array */
68};
69
70/*
71 * 8 buckets should be enough to cover most all current x86 systems (2019),
72 * given the way package/core/smt IDs are structured on x86. For systems
73 * that report high package counts despite having a single physical CPU
74 * package (e.g. Ampere eMAG) a little bit of sharing isn't going to hurt.
75 */
76#define PGFL_MAX_BUCKETS 8
77struct pgfreelist {
78 struct pgflbucket *pgfl_buckets[PGFL_MAX_BUCKETS];
79};
80
81/*
82 * Lock for each bucket.
83 */
84union uvm_freelist_lock {
85 kmutex_t lock;
86 uint8_t padding[COHERENCY_UNIT];
87};
88extern union uvm_freelist_lock uvm_freelist_locks[PGFL_MAX_BUCKETS];
89
90#endif /* _UVM_UVM_PGLIST_H_ */