On 3/10/20 5:00 AM, Nikolay Borisov wrote:
Instead of iterating all pending tickets on the normal/priority list to
sum their total size the cost can be amortized across ticket addition/
removal. This turns O(n) + O(m) (where n is the size of the normal list
and m of the priority list) into O(1). This will mostly have effect in workloads
that experience heavy flushing.
Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
---
fs/btrfs/space-info.c | 13 ++++++++-----
fs/btrfs/space-info.h | 4 ++++
2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 9cb511d8cd9d..316a724dc990 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -389,6 +389,8 @@ void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
space_info,
ticket->bytes);
list_del_init(&ticket->list);
+ ASSERT(space_info->reclaim_size >= ticket->bytes);
+ space_info->reclaim_size -= ticket->bytes;
ticket->bytes = 0;
space_info->tickets_id++;
wake_up(&ticket->wait);
@@ -784,16 +786,15 @@ static inline u64
btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info)
{
- struct reserve_ticket *ticket;
u64 used;
u64 avail;
u64 expected;
u64 to_reclaim = 0;
- list_for_each_entry(ticket, &space_info->tickets, list)
- to_reclaim += ticket->bytes;
- list_for_each_entry(ticket, &space_info->priority_tickets, list)
- to_reclaim += ticket->bytes;
+ lockdep_assert_held(&space_info->lock);
+
+ if (space_info->reclaim_size)
+ return space_info->reclaim_size;
This undoes the fix that I put up making sure we include any space we can no
longer overcommit. Thanks,
Josef
