From ac1ea10e757a57fb61512ae9beb2ef67e5340e31 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 9 Oct 2020 09:28:19 -0400 Subject: btrfs: add a trace point for reserve tickets While debugging a ENOSPC related performance problem I needed to see the time difference between start and end of a reserve ticket, so add a trace point to report when we handle a reserve ticket. I opted to spit out start_ns itself without calculating the difference because there could be a gap between enabling the tracepoint and setting start_ns. Doing it this way allows us to filter on 0 start_ns so we don't get bogus entries, and we can easily calculate the time difference with bpftrace or something else. Reviewed-by: Nikolay Borisov Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/space-info.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'fs/btrfs/space-info.c') diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c index 4eab581b1b9c..d879e3fea0b6 100644 --- a/fs/btrfs/space-info.c +++ b/fs/btrfs/space-info.c @@ -1220,6 +1220,8 @@ static void wait_reserve_ticket(struct btrfs_fs_info *fs_info, * @fs_info: the filesystem * @space_info: space info for the reservation * @ticket: ticket for the reservation + * @start_ns: timestamp when the reservation started + * @orig_bytes: amount of bytes originally reserved * @flush: how much we can flush * * This does the work of figuring out how to flush for the ticket, waiting for @@ -1228,6 +1230,7 @@ static void wait_reserve_ticket(struct btrfs_fs_info *fs_info, static int handle_reserve_ticket(struct btrfs_fs_info *fs_info, struct btrfs_space_info *space_info, struct reserve_ticket *ticket, + u64 start_ns, u64 orig_bytes, enum btrfs_reserve_flush_enum flush) { int ret; @@ -1283,6 +1286,8 @@ static int handle_reserve_ticket(struct btrfs_fs_info *fs_info, * space wasn't reserved at all). */ ASSERT(!(ticket->bytes == 0 && ticket->error)); + trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes, + start_ns, flush, ticket->error); return ret; } @@ -1317,6 +1322,7 @@ static int __reserve_bytes(struct btrfs_fs_info *fs_info, { struct work_struct *async_work; struct reserve_ticket ticket; + u64 start_ns = 0; u64 used; int ret = 0; bool pending_tickets; @@ -1369,6 +1375,9 @@ static int __reserve_bytes(struct btrfs_fs_info *fs_info, space_info->reclaim_size += ticket.bytes; init_waitqueue_head(&ticket.wait); ticket.steal = (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL); + if (trace_btrfs_reserve_ticket_enabled()) + start_ns = ktime_get_ns(); + if (flush == BTRFS_RESERVE_FLUSH_ALL || flush == BTRFS_RESERVE_FLUSH_ALL_STEAL || flush == BTRFS_RESERVE_FLUSH_DATA) { @@ -1405,7 +1414,8 @@ static int __reserve_bytes(struct btrfs_fs_info *fs_info, if (!ret || flush == BTRFS_RESERVE_NO_FLUSH) return ret; - return handle_reserve_ticket(fs_info, space_info, &ticket, flush); + return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns, + orig_bytes, flush); } /** -- cgit v1.2.3