Writeback on slow storage systems like this. PInning the cluster buffers will greatly speed up inode Of thousands of dirty inodes that need to be cleaned this can take a Mean we only clean 50 inodes a second, and when there are hundreds A RMW cycle per inode on a slow RAID6 device can Inodes in memory that can then take hours for an operation like To worry about the memory exhaustion anymore.Īnother issue is that if we have slow disks, we can build up dirty The requirement for require memory allocation for inode writebackįilesystem level, we can issue writeback asynchrnously and not have Largely guaranteed forwards progress in inode reclaim. It freed almost immediately which could then be used to allocate the Inode cluster allowed reclaim to release the inode cluster and have Immediately exhaust remaining memory reserves trying to allocate Provided a forwards progress mechanism when RMW cycles were required We used synchronous inode writeback in reclaim as a throttle that Requires allocating memory for the cluster buffer and this leads to Under memory pressure, cleaning that dirty inode to reclaim it Read-modify-write cycle on the cluster buffer. At this point cleaning the inode requires a That the cluster buffer can be reclaimed from memory and then the This is also a result of inodes being detached from the clusterīuffer except when IO is being done. Hence we are kinda stuck locking an inode before we can look The problem with this at the moment is that we we can't look up theīuffer until we have guaranteed that an inode is held exclusivelyĪnd it's not going away while we get the buffer through an imap Similar code, and it is a result of inode cluster flushing beingīased on a specific inode rather than grabbing the buffer and Initial inode, except now it has to special case that initial inode
Reclaime for xfs recovery code#
This cluster write effectively repeats the same code we do with the Optimistically lock and flush them to the buffer without blocking. We then walk all the other cached inodes in the buffer range and Then lock the underlying buffer, flush the inode to the buffer andįinally add the inode to the buffer to be unlocked on IO completion. Inode flushing requires that we first lock an inode, then check it,
` (29 more replies) 0 siblings, 30 replies 81+ messages in thread 7:45 ` xfs: Don't allow logging of XFS_ISTALE inodes Dave Chinner Xfs: rework inode flushing to make inode reclaim fully asynchronous All of help / color / mirror / Atom feed * xfs: rework inode flushing to make inode reclaim fully asynchronous 7:45 Dave Chinner