Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 24ab9cd8 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: Raise thresholds for metadata writeback 



Btrfs metadata writeback is fairly expensive.  Once a tree block is written
it must be cowed before it can be changed again.  The btree writepages
code has a threshold based on a count of dirty btree bytes which is
updated as IO is sent out.

This changes btree_writepages to skip the writeout if there are less
than 32MB of dirty bytes from the btrees, improving performance
across many workloads.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 4434c33c

fs/btrfs/disk-io.c

+2 −2
Original line number Diff line number Diff line
@@ -556,7 +556,7 @@ static int btree_writepages(struct address_space *mapping, 
	if (wbc->sync_mode == WB_SYNC_NONE) {

		u64 num_dirty;

		u64 start = 0;

		unsigned long thresh = 8 * 1024 * 1024;

		unsigned long thresh = 32 * 1024 * 1024;



		if (wbc->for_kupdate)

			return 0;
@@ -690,7 +690,7 @@ struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root, 
int btrfs_write_tree_block(struct extent_buffer *buf)

{

	return btrfs_fdatawrite_range(buf->first_page->mapping, buf->start,

				      buf->start + buf->len - 1, WB_SYNC_NONE);

				      buf->start + buf->len - 1, WB_SYNC_ALL);

}



int btrfs_wait_tree_block_writeback(struct extent_buffer *buf)