bcache: Rework allocator reserves
We need a reserve for allocating buckets for new btree nodes - and now that
we've got multiple btrees, it really needs to be per btree.
This reworks the reserves so we've got separate freelists for each reserve
instead of watermarks, which seems to make things a bit cleaner, and it adds
some code so that btree_split() can make sure the reserve is available before it
starts.
Signed-off-by: Kent Overstreet <[email protected]>
diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c
index 4c9852d..bcfd96e 100644
--- a/drivers/md/bcache/alloc.c
+++ b/drivers/md/bcache/alloc.c
@@ -132,10 +132,16 @@
{
BUG_ON(GC_MARK(b) || GC_SECTORS_USED(b));
- if (fifo_used(&ca->free) > ca->watermark[WATERMARK_MOVINGGC] &&
- CACHE_REPLACEMENT(&ca->sb) == CACHE_REPLACEMENT_FIFO)
- return false;
+ if (CACHE_REPLACEMENT(&ca->sb) == CACHE_REPLACEMENT_FIFO) {
+ unsigned i;
+ for (i = 0; i < RESERVE_NONE; i++)
+ if (!fifo_full(&ca->free[i]))
+ goto add;
+
+ return false;
+ }
+add:
b->prio = 0;
if (can_inc_bucket_gen(b) &&
@@ -304,6 +310,21 @@
__set_current_state(TASK_RUNNING); \
} while (0)
+static int bch_allocator_push(struct cache *ca, long bucket)
+{
+ unsigned i;
+
+ /* Prios/gens are actually the most important reserve */
+ if (fifo_push(&ca->free[RESERVE_PRIO], bucket))
+ return true;
+
+ for (i = 0; i < RESERVE_NR; i++)
+ if (fifo_push(&ca->free[i], bucket))
+ return true;
+
+ return false;
+}
+
static int bch_allocator_thread(void *arg)
{
struct cache *ca = arg;
@@ -336,9 +357,7 @@
mutex_lock(&ca->set->bucket_lock);
}
- allocator_wait(ca, !fifo_full(&ca->free));
-
- fifo_push(&ca->free, bucket);
+ allocator_wait(ca, bch_allocator_push(ca, bucket));
wake_up(&ca->set->bucket_wait);
}
@@ -365,34 +384,29 @@
}
}
-long bch_bucket_alloc(struct cache *ca, unsigned watermark, bool wait)
+long bch_bucket_alloc(struct cache *ca, unsigned reserve, bool wait)
{
DEFINE_WAIT(w);
struct bucket *b;
long r;
/* fastpath */
- if (fifo_used(&ca->free) > ca->watermark[watermark]) {
- fifo_pop(&ca->free, r);
+ if (fifo_pop(&ca->free[RESERVE_NONE], r) ||
+ fifo_pop(&ca->free[reserve], r))
goto out;
- }
if (!wait)
return -1;
- while (1) {
- if (fifo_used(&ca->free) > ca->watermark[watermark]) {
- fifo_pop(&ca->free, r);
- break;
- }
-
+ do {
prepare_to_wait(&ca->set->bucket_wait, &w,
TASK_UNINTERRUPTIBLE);
mutex_unlock(&ca->set->bucket_lock);
schedule();
mutex_lock(&ca->set->bucket_lock);
- }
+ } while (!fifo_pop(&ca->free[RESERVE_NONE], r) &&
+ !fifo_pop(&ca->free[reserve], r));
finish_wait(&ca->set->bucket_wait, &w);
out:
@@ -401,12 +415,14 @@
if (expensive_debug_checks(ca->set)) {
size_t iter;
long i;
+ unsigned j;
for (iter = 0; iter < prio_buckets(ca) * 2; iter++)
BUG_ON(ca->prio_buckets[iter] == (uint64_t) r);
- fifo_for_each(i, &ca->free, iter)
- BUG_ON(i == r);
+ for (j = 0; j < RESERVE_NR; j++)
+ fifo_for_each(i, &ca->free[j], iter)
+ BUG_ON(i == r);
fifo_for_each(i, &ca->free_inc, iter)
BUG_ON(i == r);
fifo_for_each(i, &ca->unused, iter)
@@ -419,7 +435,7 @@
SET_GC_SECTORS_USED(b, ca->sb.bucket_size);
- if (watermark <= WATERMARK_METADATA) {
+ if (reserve <= RESERVE_PRIO) {
SET_GC_MARK(b, GC_MARK_METADATA);
SET_GC_MOVE(b, 0);
b->prio = BTREE_PRIO;
@@ -445,7 +461,7 @@
}
}
-int __bch_bucket_alloc_set(struct cache_set *c, unsigned watermark,
+int __bch_bucket_alloc_set(struct cache_set *c, unsigned reserve,
struct bkey *k, int n, bool wait)
{
int i;
@@ -459,7 +475,7 @@
for (i = 0; i < n; i++) {
struct cache *ca = c->cache_by_alloc[i];
- long b = bch_bucket_alloc(ca, watermark, wait);
+ long b = bch_bucket_alloc(ca, reserve, wait);
if (b == -1)
goto err;
@@ -478,12 +494,12 @@
return -1;
}
-int bch_bucket_alloc_set(struct cache_set *c, unsigned watermark,
+int bch_bucket_alloc_set(struct cache_set *c, unsigned reserve,
struct bkey *k, int n, bool wait)
{
int ret;
mutex_lock(&c->bucket_lock);
- ret = __bch_bucket_alloc_set(c, watermark, k, n, wait);
+ ret = __bch_bucket_alloc_set(c, reserve, k, n, wait);
mutex_unlock(&c->bucket_lock);
return ret;
}
@@ -573,8 +589,8 @@
while (!(b = pick_data_bucket(c, k, write_point, &alloc.key))) {
unsigned watermark = write_prio
- ? WATERMARK_MOVINGGC
- : WATERMARK_NONE;
+ ? RESERVE_MOVINGGC
+ : RESERVE_NONE;
spin_unlock(&c->data_bucket_lock);
@@ -689,7 +705,7 @@
* Then 8 for btree allocations
* Then half for the moving garbage collector
*/
-
+#if 0
ca->watermark[WATERMARK_PRIO] = 0;
ca->watermark[WATERMARK_METADATA] = prio_buckets(ca);
@@ -699,6 +715,6 @@
ca->watermark[WATERMARK_NONE] = ca->free.size / 2 +
ca->watermark[WATERMARK_MOVINGGC];
-
+#endif
return 0;
}
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 9d062bc..94d346e 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -383,12 +383,12 @@
unsigned writeback_rate_p_term_inverse;
};
-enum alloc_watermarks {
- WATERMARK_PRIO,
- WATERMARK_METADATA,
- WATERMARK_MOVINGGC,
- WATERMARK_NONE,
- WATERMARK_MAX
+enum alloc_reserve {
+ RESERVE_BTREE,
+ RESERVE_PRIO,
+ RESERVE_MOVINGGC,
+ RESERVE_NONE,
+ RESERVE_NR,
};
struct cache {
@@ -400,8 +400,6 @@
struct kobject kobj;
struct block_device *bdev;
- unsigned watermark[WATERMARK_MAX];
-
struct task_struct *alloc_thread;
struct closure prio;
@@ -430,7 +428,7 @@
* because all the data they contained was overwritten), so we only
* need to discard them before they can be moved to the free list.
*/
- DECLARE_FIFO(long, free);
+ DECLARE_FIFO(long, free)[RESERVE_NR];
DECLARE_FIFO(long, free_inc);
DECLARE_FIFO(long, unused);
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 101231f..6a0f5fa 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -167,6 +167,8 @@
_r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__); \
} \
rw_unlock(_w, _b); \
+ if (_r == -EINTR) \
+ schedule(); \
bch_cannibalize_unlock(c); \
if (_r == -ENOSPC) { \
wait_event((c)->try_wait, \
@@ -175,6 +177,7 @@
} \
} while (_r == -EINTR); \
\
+ finish_wait(&(c)->bucket_wait, &(op)->wait); \
_r; \
})
@@ -1075,7 +1078,7 @@
mutex_lock(&c->bucket_lock);
retry:
- if (__bch_bucket_alloc_set(c, WATERMARK_METADATA, &k.key, 1, wait))
+ if (__bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, 1, wait))
goto err;
bkey_put(c, &k.key);
@@ -1132,6 +1135,28 @@
atomic_inc(&b->c->prio_blocked);
}
+static int btree_check_reserve(struct btree *b, struct btree_op *op)
+{
+ struct cache_set *c = b->c;
+ struct cache *ca;
+ unsigned i, reserve = c->root->level * 2 + 1;
+ int ret = 0;
+
+ mutex_lock(&c->bucket_lock);
+
+ for_each_cache(ca, c, i)
+ if (fifo_used(&ca->free[RESERVE_BTREE]) < reserve) {
+ if (op)
+ prepare_to_wait(&c->bucket_wait, &op->wait,
+ TASK_UNINTERRUPTIBLE);
+ ret = -EINTR;
+ break;
+ }
+
+ mutex_unlock(&c->bucket_lock);
+ return ret;
+}
+
/* Garbage collection */
uint8_t __bch_btree_mark_key(struct cache_set *c, int level, struct bkey *k)
@@ -1428,7 +1453,8 @@
if (!IS_ERR(last->b)) {
should_rewrite = btree_gc_mark_node(last->b, gc);
- if (should_rewrite) {
+ if (should_rewrite &&
+ !btree_check_reserve(b, NULL)) {
n = btree_node_alloc_replacement(last->b,
false);
@@ -2071,6 +2097,10 @@
closure_init_stack(&cl);
bch_keylist_init(&parent_keys);
+ if (!b->level &&
+ btree_check_reserve(b, op))
+ return -EINTR;
+
n1 = btree_node_alloc_replacement(b, true);
if (IS_ERR(n1))
goto err;
diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h
index d68af74..4f0378a 100644
--- a/drivers/md/bcache/btree.h
+++ b/drivers/md/bcache/btree.h
@@ -241,6 +241,9 @@
/* Recursing down the btree */
struct btree_op {
+ /* for waiting on btree reserve in btree_split() */
+ wait_queue_t wait;
+
/* Btree level at which we start taking write locks */
short lock;
@@ -250,6 +253,7 @@
static inline void bch_btree_op_init(struct btree_op *op, int write_lock_level)
{
memset(op, 0, sizeof(struct btree_op));
+ init_wait(&op->wait);
op->lock = write_lock_level;
}
diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
index 052bd24..9eb60d1 100644
--- a/drivers/md/bcache/movinggc.c
+++ b/drivers/md/bcache/movinggc.c
@@ -211,7 +211,7 @@
for_each_cache(ca, c, i) {
unsigned sectors_to_move = 0;
unsigned reserve_sectors = ca->sb.bucket_size *
- min(fifo_used(&ca->free), ca->free.size / 2);
+ fifo_used(&ca->free[RESERVE_MOVINGGC]);
ca->heap.used = 0;
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index b057676..63ebef7 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -444,7 +444,7 @@
lockdep_assert_held(&bch_register_lock);
- if (bch_bucket_alloc_set(c, WATERMARK_METADATA, &k.key, 1, true))
+ if (bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, 1, true))
return 1;
SET_KEY_SIZE(&k.key, c->sb.bucket_size);
@@ -562,8 +562,8 @@
atomic_long_add(ca->sb.bucket_size * prio_buckets(ca),
&ca->meta_sectors_written);
- pr_debug("free %zu, free_inc %zu, unused %zu", fifo_used(&ca->free),
- fifo_used(&ca->free_inc), fifo_used(&ca->unused));
+ //pr_debug("free %zu, free_inc %zu, unused %zu", fifo_used(&ca->free),
+ // fifo_used(&ca->free_inc), fifo_used(&ca->unused));
for (i = prio_buckets(ca) - 1; i >= 0; --i) {
long bucket;
@@ -582,7 +582,7 @@
p->magic = pset_magic(&ca->sb);
p->csum = bch_crc64(&p->magic, bucket_bytes(ca) - 8);
- bucket = bch_bucket_alloc(ca, WATERMARK_PRIO, true);
+ bucket = bch_bucket_alloc(ca, RESERVE_PRIO, true);
BUG_ON(bucket == -1);
mutex_unlock(&ca->set->bucket_lock);
@@ -1767,6 +1767,7 @@
void bch_cache_release(struct kobject *kobj)
{
struct cache *ca = container_of(kobj, struct cache, kobj);
+ unsigned i;
if (ca->set)
ca->set->cache[ca->sb.nr_this_dev] = NULL;
@@ -1780,7 +1781,9 @@
free_heap(&ca->heap);
free_fifo(&ca->unused);
free_fifo(&ca->free_inc);
- free_fifo(&ca->free);
+
+ for (i = 0; i < RESERVE_NR; i++)
+ free_fifo(&ca->free[i]);
if (ca->sb_bio.bi_inline_vecs[0].bv_page)
put_page(ca->sb_bio.bi_io_vec[0].bv_page);
@@ -1806,10 +1809,12 @@
ca->journal.bio.bi_max_vecs = 8;
ca->journal.bio.bi_io_vec = ca->journal.bio.bi_inline_vecs;
- free = roundup_pow_of_two(ca->sb.nbuckets) >> 9;
- free = max_t(size_t, free, (prio_buckets(ca) + 8) * 2);
+ free = roundup_pow_of_two(ca->sb.nbuckets) >> 10;
- if (!init_fifo(&ca->free, free, GFP_KERNEL) ||
+ if (!init_fifo(&ca->free[RESERVE_BTREE], 8, GFP_KERNEL) ||
+ !init_fifo(&ca->free[RESERVE_PRIO], prio_buckets(ca), GFP_KERNEL) ||
+ !init_fifo(&ca->free[RESERVE_MOVINGGC], free, GFP_KERNEL) ||
+ !init_fifo(&ca->free[RESERVE_NONE], free, GFP_KERNEL) ||
!init_fifo(&ca->free_inc, free << 2, GFP_KERNEL) ||
!init_fifo(&ca->unused, free << 2, GFP_KERNEL) ||
!init_heap(&ca->heap, free << 3, GFP_KERNEL) ||
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index a1f8561..d5dd282 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -102,7 +102,6 @@
rw_attribute(key_merging_disabled);
rw_attribute(gc_always_rewrite);
rw_attribute(expensive_debug_checks);
-rw_attribute(freelist_percent);
rw_attribute(cache_replacement_policy);
rw_attribute(btree_shrinker_disabled);
rw_attribute(copy_gc_enabled);
@@ -711,9 +710,6 @@
sysfs_print(io_errors,
atomic_read(&ca->io_errors) >> IO_ERROR_SHIFT);
- sysfs_print(freelist_percent, ca->free.size * 100 /
- ((size_t) ca->sb.nbuckets));
-
if (attr == &sysfs_cache_replacement_policy)
return bch_snprint_string_list(buf, PAGE_SIZE,
cache_replacement_policies,
@@ -820,32 +816,6 @@
}
}
- if (attr == &sysfs_freelist_percent) {
- DECLARE_FIFO(long, free);
- long i;
- size_t p = strtoul_or_return(buf);
-
- p = clamp_t(size_t,
- ((size_t) ca->sb.nbuckets * p) / 100,
- roundup_pow_of_two(ca->sb.nbuckets) >> 9,
- ca->sb.nbuckets / 2);
-
- if (!init_fifo_exact(&free, p, GFP_KERNEL))
- return -ENOMEM;
-
- mutex_lock(&ca->set->bucket_lock);
-
- fifo_move(&free, &ca->free);
- fifo_swap(&free, &ca->free);
-
- mutex_unlock(&ca->set->bucket_lock);
-
- while (fifo_pop(&free, i))
- atomic_dec(&ca->buckets[i].pin);
-
- free_fifo(&free);
- }
-
if (attr == &sysfs_clear_stats) {
atomic_long_set(&ca->sectors_written, 0);
atomic_long_set(&ca->btree_sectors_written, 0);
@@ -869,7 +839,6 @@
&sysfs_metadata_written,
&sysfs_io_errors,
&sysfs_clear_stats,
- &sysfs_freelist_percent,
&sysfs_cache_replacement_policy,
NULL
};
diff --git a/include/trace/events/bcache.h b/include/trace/events/bcache.h
index 095c6e4..0c5cf2f 100644
--- a/include/trace/events/bcache.h
+++ b/include/trace/events/bcache.h
@@ -411,7 +411,7 @@
),
TP_fast_assign(
- __entry->free = fifo_used(&ca->free);
+ __entry->free = fifo_used(&ca->free[RESERVE_NONE]);
__entry->free_inc = fifo_used(&ca->free_inc);
__entry->free_inc_size = ca->free_inc.size;
__entry->unused = fifo_used(&ca->unused);
@@ -422,8 +422,8 @@
);
TRACE_EVENT(bcache_alloc_fail,
- TP_PROTO(struct cache *ca),
- TP_ARGS(ca),
+ TP_PROTO(struct cache *ca, unsigned reserve),
+ TP_ARGS(ca, reserve),
TP_STRUCT__entry(
__field(unsigned, free )
@@ -433,7 +433,7 @@
),
TP_fast_assign(
- __entry->free = fifo_used(&ca->free);
+ __entry->free = fifo_used(&ca->free[reserve]);
__entry->free_inc = fifo_used(&ca->free_inc);
__entry->unused = fifo_used(&ca->unused);
__entry->blocked = atomic_read(&ca->set->prio_blocked);
