On Mon, Apr 29, 2019 at 02:03:33PM +0800, Qu Wenruo wrote: > Add trace event for update_bytes_pinned() and update_bytes_may_use() to > detect underflow better. > > The output would be something like (only showing data part): > > ## Buffered write start, 16K total ## > 2255.954 xfs_io/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=0 diff=4096 > 2257.169 sudo/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=4096 diff=4096 > 2257.346 sudo/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=8192 diff=4096 > 2257.542 sudo/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=12288 diff=4096 > > ## Delalloc start ## > 3727.853 kworker/u8:3-e/700 btrfs:update_bytes_may_use:(nil)U: type=DATA old=16384 diff=-16384 > > ## Space cache update ## > 3733.132 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=0 diff=65536 > 3733.169 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=65536 diff=-65536 > 3739.868 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=0 diff=65536 > 3739.891 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=65536 diff=-65536 > > These two trace events will allow bcc tool to probe btrfs_space_info > changes and detect underflow with more details (e.g. backtrace for each > update). > > Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> 1 and 2 Reviewed-by: David Sterba <dsterba@xxxxxxxx>
