1 // SPDX-License-Identifier: CDDL-1.0
2 /*
3 * CDDL HEADER START
4 *
5 * The contents of this file are subject to the terms of the
6 * Common Development and Distribution License (the "License").
7 * You may not use this file except in compliance with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or https://opensource.org/licenses/CDDL-1.0.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22
23 #include <sys/spa.h>
24 #include <sys/zio.h>
25 #include <sys/spa_impl.h>
26 #include <sys/counter.h>
27 #include <sys/zio_compress.h>
28 #include <sys/zio_checksum.h>
29 #include <sys/zfs_context.h>
30 #include <sys/arc.h>
31 #include <sys/arc_os.h>
32 #include <sys/zfs_refcount.h>
33 #include <sys/vdev.h>
34 #include <sys/vdev_trim.h>
35 #include <sys/vdev_impl.h>
36 #include <sys/dsl_pool.h>
37 #include <sys/zio_checksum.h>
38 #include <sys/multilist.h>
39 #include <sys/abd.h>
40 #include <sys/zil.h>
41 #include <sys/fm/fs/zfs.h>
42 #include <sys/eventhandler.h>
43 #include <sys/callb.h>
44 #include <sys/kstat.h>
45 #include <sys/zthr.h>
46 #include <zfs_fletcher.h>
47 #include <sys/arc_impl.h>
48 #include <sys/sdt.h>
49 #include <sys/aggsum.h>
50 #include <sys/vnode.h>
51 #include <cityhash.h>
52 #include <machine/vmparam.h>
53 #include <sys/vm.h>
54 #include <sys/vmmeter.h>
55
56 extern struct vfsops zfs_vfsops;
57
58 uint_t zfs_arc_free_target = 0;
59
60 static void
arc_free_target_init(void * unused __unused)61 arc_free_target_init(void *unused __unused)
62 {
63 zfs_arc_free_target = vm_cnt.v_free_target;
64 }
65 SYSINIT(arc_free_target_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_ANY,
66 arc_free_target_init, NULL);
67
68 /*
69 * We don't have a tunable for arc_free_target due to the dependency on
70 * pagedaemon initialisation.
71 */
72 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, free_target,
73 param_set_arc_free_target, 0, CTLFLAG_RW,
74 "Desired number of free pages below which ARC triggers reclaim");
75 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, no_grow_shift,
76 param_set_arc_no_grow_shift, 0, ZMOD_RW,
77 "log2(fraction of ARC which must be free to allow growing)");
78
79 int64_t
arc_available_memory(void)80 arc_available_memory(void)
81 {
82 int64_t lowest = INT64_MAX;
83 int64_t n __unused;
84
85 /*
86 * Cooperate with pagedaemon when it's time for it to scan
87 * and reclaim some pages.
88 */
89 n = PAGESIZE * ((int64_t)freemem - zfs_arc_free_target);
90 if (n < lowest) {
91 lowest = n;
92 }
93 #if !defined(UMA_MD_SMALL_ALLOC) && !defined(UMA_USE_DMAP)
94 /*
95 * If we're on a platform without a direct map, it's possible that we'll
96 * exhaust the kernel heap space before we ever run out of available
97 * physical memory. Most checks of the size of the heap_area compare
98 * against tune.t_minarmem, which is the minimum available real memory
99 * that we can have in the system. However, this is generally fixed at
100 * 25 pages which is so low that it's useless. In this comparison, we
101 * seek to calculate the total heap-size, and reclaim if more than
102 * 3/4ths of the heap is allocated. (Or, in the calculation, if less
103 * than 1/4th is free)
104 */
105 n = uma_avail() - (long)(uma_limit() / 4);
106 if (n < lowest) {
107 lowest = n;
108 }
109 #endif
110
111 DTRACE_PROBE1(arc__available_memory, int64_t, lowest);
112 return (lowest);
113 }
114
115 /*
116 * Return a default max arc size based on the amount of physical memory.
117 */
118 uint64_t
arc_default_max(uint64_t min,uint64_t allmem)119 arc_default_max(uint64_t min, uint64_t allmem)
120 {
121 uint64_t size;
122
123 if (allmem >= 1 << 30)
124 size = allmem - (1 << 30);
125 else
126 size = min;
127 return (MAX(allmem * 5 / 8, size));
128 }
129
130 uint64_t
arc_all_memory(void)131 arc_all_memory(void)
132 {
133 return (ptob(physmem));
134 }
135
136 int
arc_memory_throttle(spa_t * spa,uint64_t reserve,uint64_t txg)137 arc_memory_throttle(spa_t *spa, uint64_t reserve, uint64_t txg)
138 {
139 return (0);
140 }
141
142 uint64_t
arc_free_memory(void)143 arc_free_memory(void)
144 {
145 return (ptob(freemem));
146 }
147
148 static eventhandler_tag arc_event_lowmem = NULL;
149
150 static void
arc_lowmem(void * arg __unused,int howto __unused)151 arc_lowmem(void *arg __unused, int howto __unused)
152 {
153 int64_t can_free, free_memory, to_free;
154
155 arc_no_grow = B_TRUE;
156 arc_warm = B_TRUE;
157 arc_growtime = gethrtime() + SEC2NSEC(arc_grow_retry);
158
159 free_memory = arc_available_memory();
160 can_free = arc_c - arc_c_min;
161 to_free = (MAX(can_free, 0) >> arc_shrink_shift) - MIN(free_memory, 0);
162 DTRACE_PROBE2(arc__needfree, int64_t, free_memory, int64_t, to_free);
163 to_free = arc_reduce_target_size(to_free);
164
165 /*
166 * It is unsafe to block here in arbitrary threads, because we can come
167 * here from ARC itself and may hold ARC locks and thus risk a deadlock
168 * with ARC reclaim thread.
169 */
170 if (curproc == pageproc) {
171 arc_wait_for_eviction(to_free, B_FALSE, B_FALSE);
172 ARCSTAT_BUMP(arcstat_memory_indirect_count);
173 } else {
174 ARCSTAT_BUMP(arcstat_memory_direct_count);
175 }
176 }
177
178 void
arc_lowmem_init(void)179 arc_lowmem_init(void)
180 {
181 arc_event_lowmem = EVENTHANDLER_REGISTER(vm_lowmem, arc_lowmem, NULL,
182 EVENTHANDLER_PRI_FIRST);
183 }
184
185 void
arc_lowmem_fini(void)186 arc_lowmem_fini(void)
187 {
188 if (arc_event_lowmem != NULL)
189 EVENTHANDLER_DEREGISTER(vm_lowmem, arc_event_lowmem);
190 }
191
192 void
arc_register_hotplug(void)193 arc_register_hotplug(void)
194 {
195 }
196
197 void
arc_unregister_hotplug(void)198 arc_unregister_hotplug(void)
199 {
200 }
201