bcache: Better full stripe scanning
The old scanning-by-stripe code burned too much CPU, this should be
better.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 816d079..ab0b215 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -237,7 +237,7 @@
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 @@
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;
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 6def7c9..5e2765a 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -2378,6 +2378,7 @@
struct refill {
struct btree_op op;
+ unsigned nr_found;
struct keybuf *buf;
struct bkey *end;
keybuf_pred_fn *pred;
@@ -2414,6 +2415,8 @@
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;
@@ -2434,18 +2437,18 @@
cond_resched();
bch_btree_op_init(&refill.op, -1);
- refill.buf = buf;
- refill.end = end;
- refill.pred = pred;
+ refill.nr_found = 0;
+ refill.buf = buf;
+ refill.end = end;
+ refill.pred = pred;
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",
- KEY_INODE(&start), KEY_OFFSET(&start),
- KEY_INODE(&buf->last_scanned), KEY_OFFSET(&buf->last_scanned));
+ trace_bcache_keyscan(refill.nr_found,
+ KEY_INODE(&start), KEY_OFFSET(&start),
+ KEY_INODE(&buf->last_scanned),
+ KEY_OFFSET(&buf->last_scanned));
spin_lock(&buf->lock);
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 4813ef6..43fcfe3 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -738,6 +738,10 @@
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 @@
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 @@
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)) ||
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index ab0f6b4..22e21dc 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -292,14 +292,12 @@
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 @@
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 @@
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));
- do_div(stripe, dc->disk.stripe_size);
+ if (stripe >= dc->disk.nr_stripes)
+ stripe = 0;
+
+ 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);
- }
+ bch_refill_keybuf(dc->disk.c, buf, &end, dirty_pred);
return bkey_cmp(&buf->last_scanned, &end) >= 0 && searched_from_start;
}
diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h
index 60516bf..fe7d9d5 100644
--- a/drivers/md/bcache/writeback.h
+++ b/drivers/md/bcache/writeback.h
@@ -14,22 +14,27 @@
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 @@
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;