Commit 31b9655f authored by Josef Bacik's avatar Josef Bacik Committed by Chris Mason
Browse files

Btrfs: track transid for delayed ref flushing 



Using the offwakecputime bpf script I noticed most of our time was spent waiting
on the delayed ref throttling.  This is what is supposed to happen, but
sometimes the transaction can commit and then we're waiting for throttling that
doesn't matter anymore.  So change this stuff to be a little smarter by tracking
the transid we were in when we initiated the throttling.  If the transaction we
get is different then we can just bail out.  This resulted in a 50% speedup in
my fs_mark test, and reduced the amount of time spent throttling by 60 seconds
over the entire run (which is about 30 minutes).  Thanks,

Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent de18c165

fs/btrfs/ctree.h

+1 −1
Original line number Diff line number Diff line
@@ -2518,7 +2518,7 @@ void btrfs_put_block_group(struct btrfs_block_group_cache *cache); 
int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,

			   struct btrfs_root *root, unsigned long count);

int btrfs_async_run_delayed_refs(struct btrfs_root *root,

				 unsigned long count, int wait);

				 unsigned long count, u64 transid, int wait);

int btrfs_lookup_data_extent(struct btrfs_root *root, u64 start, u64 len);

int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,

			     struct btrfs_root *root, u64 bytenr,

fs/btrfs/extent-tree.c

+12 −3
Original line number Diff line number Diff line
@@ -2835,6 +2835,7 @@ int btrfs_should_throttle_delayed_refs(struct btrfs_trans_handle *trans, 


struct async_delayed_refs {

	struct btrfs_root *root;

	u64 transid;

	int count;

	int error;

	int sync;
@@ -2850,12 +2851,19 @@ static void delayed_ref_async_start(struct btrfs_work *work) 


	async = container_of(work, struct async_delayed_refs, work);



	trans = btrfs_join_transaction(async->root);

	trans = btrfs_attach_transaction(async->root);

	if (IS_ERR(trans)) {

		if (PTR_ERR(trans) != -ENOENT)

			async->error = PTR_ERR(trans);

		goto done;

	}



	/* Don't bother flushing if we got into a different transaction */

	if (trans->transid != async->transid) {

		btrfs_end_transaction(trans, async->root);

		goto done;

	}



	/*

	 * trans->sync means that when we call end_transaction, we won't

	 * wait on delayed refs
@@ -2876,7 +2884,7 @@ done: 
}



int btrfs_async_run_delayed_refs(struct btrfs_root *root,

				 unsigned long count, int wait)

				 unsigned long count, u64 transid, int wait)

{

	struct async_delayed_refs *async;

	int ret;
@@ -2888,6 +2896,7 @@ int btrfs_async_run_delayed_refs(struct btrfs_root *root, 
	async->root = root->fs_info->tree_root;

	async->count = count;

	async->error = 0;

	async->transid = transid;

	if (wait)

		async->sync = 1;

	else

fs/btrfs/inode.c

+1 −0
Original line number Diff line number Diff line
@@ -4558,6 +4558,7 @@ delete: 
			BUG_ON(ret);

			if (btrfs_should_throttle_delayed_refs(trans, root))

				btrfs_async_run_delayed_refs(root,

							     trans->transid,

					trans->delayed_ref_updates * 2, 0);

			if (be_nice) {

				if (truncate_space_check(trans, root,

fs/btrfs/transaction.c

+2 −1
Original line number Diff line number Diff line
@@ -818,6 +818,7 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, 
{

	struct btrfs_transaction *cur_trans = trans->transaction;

	struct btrfs_fs_info *info = root->fs_info;

	u64 transid = trans->transid;

	unsigned long cur = trans->delayed_ref_updates;

	int lock = (trans->type != TRANS_JOIN_NOLOCK);

	int err = 0;
@@ -905,7 +906,7 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, 


	kmem_cache_free(btrfs_trans_handle_cachep, trans);

	if (must_run_delayed_refs) {

		btrfs_async_run_delayed_refs(root, cur,

		btrfs_async_run_delayed_refs(root, cur, transid,

					     must_run_delayed_refs == 1);

	}

	return err;

CRA Git | Maintained and supported by SUSTech CRA and CCSE