Commit 48a915a8 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcache: Better full stripe scanning 



The old scanning-by-stripe code burned too much CPU, this should be
better.

Signed-off-by: default avatarKent Overstreet <kmo@daterainc.com>
parent 17e21a9f

drivers/md/bcache/bcache.h

+3 −2
Original line number Diff line number Diff line
@@ -237,7 +237,7 @@ struct keybuf { 


	struct rb_root		keys;



#define KEYBUF_NR		100

#define KEYBUF_NR		500

	DECLARE_ARRAY_ALLOCATOR(struct keybuf_key, freelist, KEYBUF_NR);

};
@@ -273,9 +273,10 @@ struct bcache_device { 
	atomic_t		detaching;

	int			flush_done;



	uint64_t		nr_stripes;

	unsigned		nr_stripes;

	unsigned		stripe_size;

	atomic_t		*stripe_sectors_dirty;

	unsigned long		*full_dirty_stripes;



	unsigned long		sectors_dirty_last;

	long			sectors_dirty_derivative;

drivers/md/bcache/btree.c

+11 −8
Original line number Diff line number Diff line
@@ -2378,6 +2378,7 @@ static inline int keybuf_nonoverlapping_cmp(struct keybuf_key *l, 


struct refill {

	struct btree_op	op;

	unsigned	nr_found;

	struct keybuf	*buf;

	struct bkey	*end;

	keybuf_pred_fn	*pred;
@@ -2414,6 +2415,8 @@ static int refill_keybuf_fn(struct btree_op *op, struct btree *b, 


		if (RB_INSERT(&buf->keys, w, node, keybuf_cmp))

			array_free(&buf->freelist, w);

		else

			refill->nr_found++;



		if (array_freelist_empty(&buf->freelist))

			ret = MAP_DONE;
@@ -2434,6 +2437,7 @@ void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf, 
	cond_resched();



	bch_btree_op_init(&refill.op, -1);

	refill.nr_found	= 0;

	refill.buf	= buf;

	refill.end	= end;

	refill.pred	= pred;
@@ -2441,11 +2445,10 @@ void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf, 
	bch_btree_map_keys(&refill.op, c, &buf->last_scanned,

			   refill_keybuf_fn, MAP_END_KEY);



	pr_debug("found %s keys from %llu:%llu to %llu:%llu",

		 RB_EMPTY_ROOT(&buf->keys) ? "no" :

		 array_freelist_empty(&buf->freelist) ? "some" : "a few",

	trace_bcache_keyscan(refill.nr_found,

			     KEY_INODE(&start), KEY_OFFSET(&start),

		 KEY_INODE(&buf->last_scanned), KEY_OFFSET(&buf->last_scanned));

			     KEY_INODE(&buf->last_scanned),

			     KEY_OFFSET(&buf->last_scanned));



	spin_lock(&buf->lock);

drivers/md/bcache/super.c

+16 −1
Original line number Diff line number Diff line
@@ -738,6 +738,10 @@ static void bcache_device_free(struct bcache_device *d) 
		mempool_destroy(d->unaligned_bvec);

	if (d->bio_split)

		bioset_free(d->bio_split);

	if (is_vmalloc_addr(d->full_dirty_stripes))

		vfree(d->full_dirty_stripes);

	else

		kfree(d->full_dirty_stripes);

	if (is_vmalloc_addr(d->stripe_sectors_dirty))

		vfree(d->stripe_sectors_dirty);

	else
@@ -757,8 +761,12 @@ static int bcache_device_init(struct bcache_device *d, unsigned block_size, 


	d->nr_stripes = DIV_ROUND_UP_ULL(sectors, d->stripe_size);



	if (!d->nr_stripes || d->nr_stripes > SIZE_MAX / sizeof(atomic_t))

	if (!d->nr_stripes ||

	    d->nr_stripes > INT_MAX ||

	    d->nr_stripes > SIZE_MAX / sizeof(atomic_t)) {

		pr_err("nr_stripes too large");

		return -ENOMEM;

	}



	n = d->nr_stripes * sizeof(atomic_t);

	d->stripe_sectors_dirty = n < PAGE_SIZE << 6
@@ -767,6 +775,13 @@ static int bcache_device_init(struct bcache_device *d, unsigned block_size, 
	if (!d->stripe_sectors_dirty)

		return -ENOMEM;



	n = BITS_TO_LONGS(d->nr_stripes) * sizeof(unsigned long);

	d->full_dirty_stripes = n < PAGE_SIZE << 6

		? kzalloc(n, GFP_KERNEL)

		: vzalloc(n);

	if (!d->full_dirty_stripes)

		return -ENOMEM;



	if (!(d->bio_split = bioset_create(4, offsetof(struct bbio, bio))) ||

	    !(d->unaligned_bvec = mempool_create_kmalloc_pool(1,

				sizeof(struct bio_vec) * BIO_MAX_PAGES)) ||

drivers/md/bcache/writeback.c

+56 −38
Original line number Diff line number Diff line
@@ -292,14 +292,12 @@ void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned inode, 
				  uint64_t offset, int nr_sectors)

{

	struct bcache_device *d = c->devices[inode];

	unsigned stripe_offset;

	uint64_t stripe = offset;

	unsigned stripe_offset, stripe, sectors_dirty;



	if (!d)

		return;



	do_div(stripe, d->stripe_size);



	stripe = offset_to_stripe(d, offset);

	stripe_offset = offset & (d->stripe_size - 1);



	while (nr_sectors) {
@@ -309,7 +307,16 @@ void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned inode, 
		if (nr_sectors < 0)

			s = -s;



		atomic_add(s, d->stripe_sectors_dirty + stripe);

		if (stripe >= d->nr_stripes)

			return;



		sectors_dirty = atomic_add_return(s,

					d->stripe_sectors_dirty + stripe);

		if (sectors_dirty == d->stripe_size)

			set_bit(stripe, d->full_dirty_stripes);

		else

			clear_bit(stripe, d->full_dirty_stripes);



		nr_sectors -= s;

		stripe_offset = 0;

		stripe++;
@@ -321,59 +328,70 @@ 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)

static void refill_full_stripes(struct cached_dev *dc)

{

	uint64_t stripe = KEY_START(k);

	unsigned nr_sectors = KEY_SIZE(k);

	struct cached_dev *dc = container_of(buf, struct cached_dev,

					     writeback_keys);

	struct keybuf *buf = &dc->writeback_keys;

	unsigned start_stripe, stripe, next_stripe;

	bool wrapped = false;



	if (!KEY_DIRTY(k))

		return false;

	stripe = offset_to_stripe(&dc->disk, KEY_OFFSET(&buf->last_scanned));



	if (stripe >= dc->disk.nr_stripes)

		stripe = 0;



	do_div(stripe, dc->disk.stripe_size);

	start_stripe = stripe;



	while (1) {

		if (atomic_read(dc->disk.stripe_sectors_dirty + stripe) ==

		    dc->disk.stripe_size)

			return true;

		stripe = find_next_bit(dc->disk.full_dirty_stripes,

				       dc->disk.nr_stripes, stripe);



		if (nr_sectors <= dc->disk.stripe_size)

			return false;

		if (stripe == dc->disk.nr_stripes)

			goto next;



		nr_sectors -= dc->disk.stripe_size;

		stripe++;

		next_stripe = find_next_zero_bit(dc->disk.full_dirty_stripes,

						 dc->disk.nr_stripes, stripe);



		buf->last_scanned = KEY(dc->disk.id,

					stripe * dc->disk.stripe_size, 0);



		bch_refill_keybuf(dc->disk.c, buf,

				  &KEY(dc->disk.id,

				       next_stripe * dc->disk.stripe_size, 0),

				  dirty_pred);



		if (array_freelist_empty(&buf->freelist))

			return;



		stripe = next_stripe;

next:

		if (wrapped && stripe > start_stripe)

			return;



		if (stripe == dc->disk.nr_stripes) {

			stripe = 0;

			wrapped = true;

		}

	}

}



static bool refill_dirty(struct cached_dev *dc)

{

	struct keybuf *buf = &dc->writeback_keys;

	bool searched_from_start = false;

	struct bkey end = KEY(dc->disk.id, MAX_KEY_OFFSET, 0);

	bool searched_from_start = false;



	if (dc->partial_stripes_expensive) {

		refill_full_stripes(dc);

		if (array_freelist_empty(&buf->freelist))

			return false;

	}



	if (bkey_cmp(&buf->last_scanned, &end) >= 0) {

		buf->last_scanned = KEY(dc->disk.id, 0, 0);

		searched_from_start = true;

	}



	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) ==

			    dc->disk.stripe_size)

				goto full_stripes;



		goto normal_refill;

full_stripes:

		searched_from_start = false;	/* not searching entire btree */

		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);

	}



	return bkey_cmp(&buf->last_scanned, &end) >= 0 && searched_from_start;

}

drivers/md/bcache/writeback.h

+13 −8
Original line number Diff line number Diff line
@@ -14,22 +14,27 @@ 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,

static inline unsigned offset_to_stripe(struct bcache_device *d,

					uint64_t offset)

{

	do_div(offset, d->stripe_size);

	return offset;

}



static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc,

					   uint64_t offset,

					   unsigned nr_sectors)

{

	uint64_t stripe = offset;



	do_div(stripe, d->stripe_size);

	unsigned stripe = offset_to_stripe(&dc->disk, offset);



	while (1) {

		if (atomic_read(d->stripe_sectors_dirty + stripe))

		if (atomic_read(dc->disk.stripe_sectors_dirty + stripe))

			return true;



		if (nr_sectors <= d->stripe_size)

		if (nr_sectors <= dc->disk.stripe_size)

			return false;



		nr_sectors -= d->stripe_size;

		nr_sectors -= dc->disk.stripe_size;

		stripe++;

	}

}
@@ -45,7 +50,7 @@ static inline bool should_writeback(struct cached_dev *dc, struct bio *bio, 
		return false;



	if (dc->partial_stripes_expensive &&

	    bcache_dev_stripe_dirty(&dc->disk, bio->bi_sector,

	    bcache_dev_stripe_dirty(dc, bio->bi_sector,

				    bio_sectors(bio)))

		return true;