2 * Moving/copying garbage collector
4 * Copyright 2012 Google, Inc.
8 #include "alloc_foreground.h"
9 #include "btree_iter.h"
10 #include "btree_update.h"
13 #include "disk_groups.h"
15 #include "eytzinger.h"
22 #include <trace/events/bcachefs.h>
23 #include <linux/freezer.h>
24 #include <linux/kthread.h>
25 #include <linux/math64.h>
26 #include <linux/sched/task.h>
27 #include <linux/sort.h>
28 #include <linux/wait.h>
31 * We can't use the entire copygc reserve in one iteration of copygc: we may
32 * need the buckets we're freeing up to go back into the copygc reserve to make
33 * forward progress, but if the copygc reserve is full they'll be available for
34 * any allocation - and it's possible that in a given iteration, we free up most
35 * of the buckets we're going to free before we allocate most of the buckets
36 * we're going to allocate.
38 * If we only use half of the reserve per iteration, then in steady state we'll
39 * always have room in the reserve for the buckets we're going to need in the
42 #define COPYGC_BUCKETS_PER_ITER(ca) \
43 ((ca)->free[RESERVE_MOVINGGC].size / 2)
46 * Max sectors to move per iteration: Have to take into account internal
47 * fragmentation from the multiple write points for each generation:
49 #define COPYGC_SECTORS_PER_ITER(ca) \
50 ((ca)->mi.bucket_size * COPYGC_BUCKETS_PER_ITER(ca))
52 static inline int sectors_used_cmp(copygc_heap *heap,
53 struct copygc_heap_entry l,
54 struct copygc_heap_entry r)
56 return cmp_int(l.sectors, r.sectors);
59 static int bucket_offset_cmp(const void *_l, const void *_r, size_t size)
61 const struct copygc_heap_entry *l = _l;
62 const struct copygc_heap_entry *r = _r;
64 return cmp_int(l->offset, r->offset);
67 static bool __copygc_pred(struct bch_dev *ca,
70 copygc_heap *h = &ca->copygc_heap;
73 case KEY_TYPE_extent: {
74 struct bkey_s_c_extent e = bkey_s_c_to_extent(k);
75 const struct bch_extent_ptr *ptr =
76 bch2_extent_has_device(e, ca->dev_idx);
79 struct copygc_heap_entry search = { .offset = ptr->offset };
81 ssize_t i = eytzinger0_find_le(h->data, h->used,
83 bucket_offset_cmp, &search);
86 ptr->offset < h->data[i].offset + ca->mi.bucket_size &&
87 ptr->gen == h->data[i].gen);
96 static enum data_cmd copygc_pred(struct bch_fs *c, void *arg,
98 struct bch_io_opts *io_opts,
99 struct data_opts *data_opts)
101 struct bch_dev *ca = arg;
103 if (!__copygc_pred(ca, k))
106 data_opts->target = dev_to_target(ca->dev_idx);
107 data_opts->btree_insert_flags = BTREE_INSERT_USE_RESERVE;
108 data_opts->rewrite_dev = ca->dev_idx;
112 static bool have_copygc_reserve(struct bch_dev *ca)
116 spin_lock(&ca->freelist_lock);
117 ret = fifo_full(&ca->free[RESERVE_MOVINGGC]) ||
118 ca->allocator_state != ALLOCATOR_RUNNING;
119 spin_unlock(&ca->freelist_lock);
124 static void bch2_copygc(struct bch_fs *c, struct bch_dev *ca)
126 copygc_heap *h = &ca->copygc_heap;
127 struct copygc_heap_entry e, *i;
128 struct bucket_array *buckets;
129 struct bch_move_stats move_stats;
130 u64 sectors_to_move = 0, sectors_not_moved = 0;
131 u64 buckets_to_move, buckets_not_moved = 0;
135 memset(&move_stats, 0, sizeof(move_stats));
136 closure_wait_event(&c->freelist_wait, have_copygc_reserve(ca));
139 * Find buckets with lowest sector counts, skipping completely
140 * empty buckets, by building a maxheap sorted by sector count,
141 * and repeatedly replacing the maximum element until all
142 * buckets have been visited.
147 * We need bucket marks to be up to date - gc can't be recalculating
150 down_read(&c->gc_lock);
151 down_read(&ca->bucket_lock);
152 buckets = bucket_array(ca);
154 for (b = buckets->first_bucket; b < buckets->nbuckets; b++) {
155 struct bucket_mark m = READ_ONCE(buckets->b[b].mark);
156 struct copygc_heap_entry e;
158 if (m.owned_by_allocator ||
159 m.data_type != BCH_DATA_USER ||
160 !bucket_sectors_used(m) ||
161 bucket_sectors_used(m) >= ca->mi.bucket_size)
164 e = (struct copygc_heap_entry) {
166 .sectors = bucket_sectors_used(m),
167 .offset = bucket_to_sector(ca, b),
169 heap_add_or_replace(h, e, -sectors_used_cmp, NULL);
171 up_read(&ca->bucket_lock);
172 up_read(&c->gc_lock);
174 for (i = h->data; i < h->data + h->used; i++)
175 sectors_to_move += i->sectors;
177 while (sectors_to_move > COPYGC_SECTORS_PER_ITER(ca)) {
178 BUG_ON(!heap_pop(h, e, -sectors_used_cmp, NULL));
179 sectors_to_move -= e.sectors;
182 buckets_to_move = h->used;
184 if (!buckets_to_move)
187 eytzinger0_sort(h->data, h->used,
189 bucket_offset_cmp, NULL);
191 ret = bch2_move_data(c, &ca->copygc_pd.rate,
192 writepoint_ptr(&ca->copygc_write_point),
197 down_read(&ca->bucket_lock);
198 buckets = bucket_array(ca);
199 for (i = h->data; i < h->data + h->used; i++) {
200 size_t b = sector_to_bucket(ca, i->offset);
201 struct bucket_mark m = READ_ONCE(buckets->b[b].mark);
203 if (i->gen == m.gen && bucket_sectors_used(m)) {
204 sectors_not_moved += bucket_sectors_used(m);
208 up_read(&ca->bucket_lock);
210 if (sectors_not_moved && !ret)
211 bch_warn_ratelimited(c,
212 "copygc finished but %llu/%llu sectors, %llu/%llu buckets not moved",
213 sectors_not_moved, sectors_to_move,
214 buckets_not_moved, buckets_to_move);
217 atomic64_read(&move_stats.sectors_moved), sectors_not_moved,
218 buckets_to_move, buckets_not_moved);
221 static int bch2_copygc_thread(void *arg)
223 struct bch_dev *ca = arg;
224 struct bch_fs *c = ca->fs;
225 struct io_clock *clock = &c->io_clock[WRITE];
226 struct bch_dev_usage usage;
228 u64 available, fragmented, reserve, next;
232 while (!kthread_should_stop()) {
233 if (kthread_wait_freezable(c->copy_gc_enabled))
236 last = atomic_long_read(&clock->now);
238 reserve = ca->copygc_threshold;
240 usage = bch2_dev_usage_read(c, ca);
242 available = __dev_buckets_available(ca, usage) *
244 if (available > reserve) {
245 next = last + available - reserve;
246 bch2_kthread_io_clock_wait(clock, next,
247 MAX_SCHEDULE_TIMEOUT);
252 * don't start copygc until there's more than half the copygc
253 * reserve of fragmented space:
255 fragmented = usage.sectors_fragmented;
256 if (fragmented < reserve) {
257 next = last + reserve - fragmented;
258 bch2_kthread_io_clock_wait(clock, next,
259 MAX_SCHEDULE_TIMEOUT);
269 void bch2_copygc_stop(struct bch_dev *ca)
271 ca->copygc_pd.rate.rate = UINT_MAX;
272 bch2_ratelimit_reset(&ca->copygc_pd.rate);
274 if (ca->copygc_thread) {
275 kthread_stop(ca->copygc_thread);
276 put_task_struct(ca->copygc_thread);
278 ca->copygc_thread = NULL;
281 int bch2_copygc_start(struct bch_fs *c, struct bch_dev *ca)
283 struct task_struct *t;
285 BUG_ON(ca->copygc_thread);
287 if (c->opts.nochanges)
290 if (bch2_fs_init_fault("copygc_start"))
293 t = kthread_create(bch2_copygc_thread, ca,
294 "bch_copygc[%s]", ca->name);
300 ca->copygc_thread = t;
301 wake_up_process(ca->copygc_thread);
306 void bch2_dev_copygc_init(struct bch_dev *ca)
308 bch2_pd_controller_init(&ca->copygc_pd);
309 ca->copygc_pd.d_term = 0;