mca_cannibalize() is used to cannibalize a btree node cache in
mca_alloc() when,
- There is no available node from c->btree_cache_freeable list.
- There is no available node from c->btree_cache_freed list.
- mca_bucket_alloc() fails to allocate new in-memory node neither.
Then mca_cannibalize() will try to shrink one node from c->btree_cache
list and allocate it to new btree node in such cannibalized way.
Now with patch "bcache: limit bcache btree node cache memory consumption
by I/O throttle", the in-memory btree nodes can be shrunk from list
c->btree_cache proactively already, in most of time there will be enough
memory to allocate. So kzalloc() in mca_bucket_alloc() will always
success, and such cannibalized allocation is almost useless. Considering
the extra complication in mca_cannibalize_lock(), it is time to remove
the unnecessary mca_cannibalize() from bcache code.
NOTE: mca_cannibalize_lock() and mca_cannibalize_unlock() are still kept
in bcache code, they are referenced by other btree related code yet.
Signed-off-by: Coly Li <colyli@xxxxxxx>
---
drivers/md/bcache/btree.c | 26 --------------------------
1 file changed, 26 deletions(-)
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index ada17113482f..48a097037da8 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -962,28 +962,6 @@ static int mca_cannibalize_lock(struct cache_set *c, struct btree_op *op)
return 0;
}
-static struct btree *mca_cannibalize(struct cache_set *c, struct btree_op *op,
- struct bkey *k)
-{
- struct btree *b;
-
- trace_bcache_btree_cache_cannibalize(c);
-
- if (mca_cannibalize_lock(c, op))
- return ERR_PTR(-EINTR);
-
- list_for_each_entry_reverse(b, &c->btree_cache, list)
- if (!mca_reap(b, btree_order(k), false))
- return b;
-
- list_for_each_entry_reverse(b, &c->btree_cache, list)
- if (!mca_reap(b, btree_order(k), true))
- return b;
-
- WARN(1, "btree cache cannibalize failed\n");
- return ERR_PTR(-ENOMEM);
-}
-
/*
* We can only have one thread cannibalizing other cached btree nodes at a time,
* or we'll deadlock. We use an open coded mutex to ensure that, which a
@@ -1072,10 +1050,6 @@ static struct btree *mca_alloc(struct cache_set *c, struct btree_op *op,
if (b)
rw_unlock(true, b);
- b = mca_cannibalize(c, op, k);
- if (!IS_ERR(b))
- goto out;
-
return b;
}
--
2.16.4
