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bcache: Write out full stripes

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Now that we're tracking dirty data per stripe, we can add two
optimizations for raid5/6:

 * If a stripe is already dirty, force writes to that stripe to
   writeback mode - to help build up full stripes of dirty data

 * When flushing dirty data, preferentially write out full stripes first
   if there are any.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
This commit is contained in:
Kent Overstreet 2013-06-05 06:24:39 -07:00
parent 279afbad4e
commit 72c270612b
9 changed files with 121 additions and 37 deletions
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3
drivers/md/bcache/bcache.h
View File

@ -387,8 +387,6 @@ struct keybuf_key {
typedef bool (keybuf_pred_fn)(struct keybuf *, struct bkey *);
struct keybuf {
keybuf_pred_fn *key_predicate;
struct bkey last_scanned;
spinlock_t lock;
@ -532,6 +530,7 @@ struct cached_dev {
unsigned sequential_merge:1;
unsigned verify:1;
unsigned partial_stripes_expensive:1;
unsigned writeback_metadata:1;
unsigned writeback_running:1;
unsigned char writeback_percent;

19
drivers/md/bcache/btree.c
View File

@ -2252,7 +2252,8 @@ static inline int keybuf_nonoverlapping_cmp(struct keybuf_key *l,
}
static int bch_btree_refill_keybuf(struct btree *b, struct btree_op *op,
struct keybuf *buf, struct bkey *end)
struct keybuf *buf, struct bkey *end,
keybuf_pred_fn *pred)
{
struct btree_iter iter;
bch_btree_iter_init(b, &iter, &buf->last_scanned);
@ -2271,7 +2272,7 @@ static int bch_btree_refill_keybuf(struct btree *b, struct btree_op *op,
if (bkey_cmp(&buf->last_scanned, end) >= 0)
break;
if (buf->key_predicate(buf, k)) {
if (pred(buf, k)) {
struct keybuf_key *w;
spin_lock(&buf->lock);
@ -2290,7 +2291,7 @@ static int bch_btree_refill_keybuf(struct btree *b, struct btree_op *op,
if (!k)
break;
btree(refill_keybuf, k, b, op, buf, end);
btree(refill_keybuf, k, b, op, buf, end, pred);
/*
* Might get an error here, but can't really do anything
* and it'll get logged elsewhere. Just read what we
@ -2308,7 +2309,7 @@ static int bch_btree_refill_keybuf(struct btree *b, struct btree_op *op,
}
void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf,
struct bkey *end)
struct bkey *end, keybuf_pred_fn *pred)
{
struct bkey start = buf->last_scanned;
struct btree_op op;
@ -2316,7 +2317,7 @@ void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf,
cond_resched();
btree_root(refill_keybuf, c, &op, buf, end);
btree_root(refill_keybuf, c, &op, buf, end, pred);
closure_sync(&op.cl);
pr_debug("found %s keys from %llu:%llu to %llu:%llu",
@ -2402,7 +2403,8 @@ struct keybuf_key *bch_keybuf_next(struct keybuf *buf)
struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c,
struct keybuf *buf,
struct bkey *end)
struct bkey *end,
keybuf_pred_fn *pred)
{
struct keybuf_key *ret;
@ -2416,15 +2418,14 @@ struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c,
break;
}
bch_refill_keybuf(c, buf, end);
bch_refill_keybuf(c, buf, end, pred);
}
return ret;
}
void bch_keybuf_init(struct keybuf *buf, keybuf_pred_fn *fn)
void bch_keybuf_init(struct keybuf *buf)
{
buf->key_predicate = fn;
buf->last_scanned = MAX_KEY;
buf->keys = RB_ROOT;

9
drivers/md/bcache/btree.h
View File

@ -391,13 +391,14 @@ void bch_moving_gc(struct closure *);
int bch_btree_check(struct cache_set *, struct btree_op *);
uint8_t __bch_btree_mark_key(struct cache_set *, int, struct bkey *);
void bch_keybuf_init(struct keybuf *, keybuf_pred_fn *);
void bch_refill_keybuf(struct cache_set *, struct keybuf *, struct bkey *);
void bch_keybuf_init(struct keybuf *);
void bch_refill_keybuf(struct cache_set *, struct keybuf *, struct bkey *,
keybuf_pred_fn *);
bool bch_keybuf_check_overlapping(struct keybuf *, struct bkey *,
struct bkey *);
void bch_keybuf_del(struct keybuf *, struct keybuf_key *);
struct keybuf_key *bch_keybuf_next(struct keybuf *);
struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *,
struct keybuf *, struct bkey *);
struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *, struct keybuf *,
struct bkey *, keybuf_pred_fn *);
#endif

4
drivers/md/bcache/debug.c
View File

@ -357,7 +357,7 @@ static ssize_t bch_dump_read(struct file *file, char __user *buf,
if (i->bytes)
break;
w = bch_keybuf_next_rescan(i->c, &i->keys, &MAX_KEY);
w = bch_keybuf_next_rescan(i->c, &i->keys, &MAX_KEY, dump_pred);
if (!w)
break;
@ -380,7 +380,7 @@ static int bch_dump_open(struct inode *inode, struct file *file)
file->private_data = i;
i->c = c;
bch_keybuf_init(&i->keys, dump_pred);
bch_keybuf_init(&i->keys);
i->keys.last_scanned = KEY(0, 0, 0);
return 0;

5
drivers/md/bcache/movinggc.c
View File

@ -136,7 +136,8 @@ static void read_moving(struct closure *cl)
/* XXX: if we error, background writeback could stall indefinitely */
while (!test_bit(CACHE_SET_STOPPING, &c->flags)) {
w = bch_keybuf_next_rescan(c, &c->moving_gc_keys, &MAX_KEY);
w = bch_keybuf_next_rescan(c, &c->moving_gc_keys,
&MAX_KEY, moving_pred);
if (!w)
break;
@ -248,5 +249,5 @@ void bch_moving_gc(struct closure *cl)
void bch_moving_init_cache_set(struct cache_set *c)
{
bch_keybuf_init(&c->moving_gc_keys, moving_pred);
bch_keybuf_init(&c->moving_gc_keys);
}

23
drivers/md/bcache/request.c
View File

@ -22,8 +22,6 @@
#define CUTOFF_CACHE_ADD 95
#define CUTOFF_CACHE_READA 90
#define CUTOFF_WRITEBACK 50
#define CUTOFF_WRITEBACK_SYNC 75
struct kmem_cache *bch_search_cache;
@ -998,17 +996,6 @@ static void cached_dev_write_complete(struct closure *cl)
cached_dev_bio_complete(cl);
}
static bool should_writeback(struct cached_dev *dc, struct bio *bio)
{
unsigned threshold = (bio->bi_rw & REQ_SYNC)
? CUTOFF_WRITEBACK_SYNC
: CUTOFF_WRITEBACK;
return !atomic_read(&dc->disk.detaching) &&
cache_mode(dc, bio) == CACHE_MODE_WRITEBACK &&
dc->disk.c->gc_stats.in_use < threshold;
}
static void request_write(struct cached_dev *dc, struct search *s)
{
struct closure *cl = &s->cl;
@ -1030,12 +1017,16 @@ static void request_write(struct cached_dev *dc, struct search *s)
if (bio->bi_rw & REQ_DISCARD)
goto skip;
if (should_writeback(dc, s->orig_bio,
cache_mode(dc, bio),
s->op.skip)) {
s->op.skip = false;
s->writeback = true;
}
if (s->op.skip)
goto skip;
if (should_writeback(dc, s->orig_bio))
s->writeback = true;
trace_bcache_write(s->orig_bio, s->writeback, s->op.skip);
if (!s->writeback) {

8
drivers/md/bcache/sysfs.c
View File

@ -81,6 +81,9 @@ rw_attribute(writeback_rate_p_term_inverse);
rw_attribute(writeback_rate_d_smooth);
read_attribute(writeback_rate_debug);
read_attribute(stripe_size);
read_attribute(partial_stripes_expensive);
rw_attribute(synchronous);
rw_attribute(journal_delay_ms);
rw_attribute(discard);
@ -147,6 +150,9 @@ SHOW(__bch_cached_dev)
sysfs_hprint(dirty_data,
bcache_dev_sectors_dirty(&dc->disk) << 9);
sysfs_hprint(stripe_size, (1 << dc->disk.stripe_size_bits) << 9);
var_printf(partial_stripes_expensive, "%u");
var_printf(sequential_merge, "%i");
var_hprint(sequential_cutoff);
var_hprint(readahead);
@ -286,6 +292,8 @@ static struct attribute *bch_cached_dev_files[] = {
&sysfs_writeback_rate_d_smooth,
&sysfs_writeback_rate_debug,
&sysfs_dirty_data,
&sysfs_stripe_size,
&sysfs_partial_stripes_expensive,
&sysfs_sequential_cutoff,
&sysfs_sequential_merge,
&sysfs_clear_stats,

44
drivers/md/bcache/writeback.c
View File

@ -108,6 +108,31 @@ static bool dirty_pred(struct keybuf *buf, struct bkey *k)
return KEY_DIRTY(k);
}
static bool dirty_full_stripe_pred(struct keybuf *buf, struct bkey *k)
{
uint64_t stripe;
unsigned nr_sectors = KEY_SIZE(k);
struct cached_dev *dc = container_of(buf, struct cached_dev,
writeback_keys);
unsigned stripe_size = 1 << dc->disk.stripe_size_bits;
if (!KEY_DIRTY(k))
return false;
stripe = KEY_START(k) >> dc->disk.stripe_size_bits;
while (1) {
if (atomic_read(dc->disk.stripe_sectors_dirty + stripe) !=
stripe_size)
return false;
if (nr_sectors <= stripe_size)
return true;
nr_sectors -= stripe_size;
stripe++;
}
}
static void dirty_init(struct keybuf_key *w)
{
struct dirty_io *io = w->private;
@ -152,7 +177,22 @@ static void refill_dirty(struct closure *cl)
searched_from_start = true;
}
bch_refill_keybuf(dc->disk.c, buf, &end);
if (dc->partial_stripes_expensive) {
uint64_t i;
for (i = 0; i < dc->disk.nr_stripes; i++)
if (atomic_read(dc->disk.stripe_sectors_dirty + i) ==
1 << dc->disk.stripe_size_bits)
goto full_stripes;
goto normal_refill;
full_stripes:
bch_refill_keybuf(dc->disk.c, buf, &end,
dirty_full_stripe_pred);
} else {
normal_refill:
bch_refill_keybuf(dc->disk.c, buf, &end, dirty_pred);
}
if (bkey_cmp(&buf->last_scanned, &end) >= 0 && searched_from_start) {
/* Searched the entire btree - delay awhile */
@ -446,7 +486,7 @@ void bch_cached_dev_writeback_init(struct cached_dev *dc)
closure_init_unlocked(&dc->writeback);
init_rwsem(&dc->writeback_lock);
bch_keybuf_init(&dc->writeback_keys, dirty_pred);
bch_keybuf_init(&dc->writeback_keys);
dc->writeback_metadata = true;
dc->writeback_running = true;

43
drivers/md/bcache/writeback.h
View File

@ -1,6 +1,9 @@
#ifndef _BCACHE_WRITEBACK_H
#define _BCACHE_WRITEBACK_H
#define CUTOFF_WRITEBACK 40
#define CUTOFF_WRITEBACK_SYNC 70
static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
{
uint64_t i, ret = 0;
@ -11,6 +14,46 @@ static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
return ret;
}
static inline bool bcache_dev_stripe_dirty(struct bcache_device *d,
uint64_t offset,
unsigned nr_sectors)
{
uint64_t stripe = offset >> d->stripe_size_bits;
while (1) {
if (atomic_read(d->stripe_sectors_dirty + stripe))
return true;
if (nr_sectors <= 1 << d->stripe_size_bits)
return false;
nr_sectors -= 1 << d->stripe_size_bits;
stripe++;
}
}
static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
unsigned cache_mode, bool would_skip)
{
unsigned in_use = dc->disk.c->gc_stats.in_use;
if (cache_mode != CACHE_MODE_WRITEBACK ||
atomic_read(&dc->disk.detaching) ||
in_use > CUTOFF_WRITEBACK_SYNC)
return false;
if (dc->partial_stripes_expensive &&
bcache_dev_stripe_dirty(&dc->disk, bio->bi_sector,
bio_sectors(bio)))
return true;
if (would_skip)
return false;
return bio->bi_rw & REQ_SYNC ||
in_use <= CUTOFF_WRITEBACK;
}
void bcache_dev_sectors_dirty_add(struct cache_set *, unsigned, uint64_t, int);
void bch_writeback_queue(struct cached_dev *);
void bch_writeback_add(struct cached_dev *);