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/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;
}
