mirror of
https://github.com/torvalds/linux.git
synced 2024-11-15 08:31:55 +00:00
9adf40249e
We have a mechanism that checks the amount of log space remaining available every time we make a transaction reservation. If the amount of space is below a threshold (25% free) we push on the AIL to tell it to do more work. To do this, we end up calculating the LSN that the AIL needs to push to on every reservation and updating the push target for the AIL with that new target LSN. This is silly and expensive. The AIL is perfectly capable of calculating the push target itself, and it will always be running when the AIL contains objects. What the target does is determine if the AIL needs to do any work before it goes back to sleep. If we haven't run out of reservation space or memory (or some other push all trigger), it will simply go back to sleep for a while if there is more than 25% of the journal space free without doing anything. If there are items in the AIL at a lower LSN than the target, it will try to push up to the target or to the point of getting stuck before going back to sleep and trying again soon after.` Hence we can modify the AIL to calculate it's own 25% push target before it starts a push using the same reserve grant head based calculation as is currently used, and remove all the places where we ask the AIL to push to a new 25% free target. We can also drop the minimum free space size of 256BBs from the calculation because the 25% of a minimum sized log is *always going to be larger than 256BBs. This does still require a manual push in certain circumstances. These circumstances arise when the AIL is not full, but the reservation grants consume the entire of the free space in the log. In this case, we still need to push on the AIL to free up space, so when we hit this condition (i.e. reservation going to sleep to wait on log space) we do a single push to tell the AIL it should empty itself. This will keep the AIL moving as new reservations come in and want more space, rather than keep queuing them and having to push the AIL repeatedly. The reason for using the "push all" when grant space runs out is that we can run out of grant space when there is more than 25% of the log free. Small logs are notorious for this, and we have a hack in the log callback code (xlog_state_set_callback()) where we push the AIL because the *head* moved) to ensure that we kick the AIL when we consume space in it because that can push us over the "less than 25% available" available that starts tail pushing back up again. Hence when we run out of grant space and are going to sleep, we have to consider that the grant space may be consuming almost all the log space and there is almost nothing in the AIL. In this situation, the AIL pins the tail and moving the tail forwards is the only way the grant space will come available, so we have to force the AIL to push everything to guarantee grant space will eventually be returned. Hence triggering a "push all" just before sleeping removes all the nasty corner cases we have in other parts of the code that work around the "we didn't ask the AIL to push enough to free grant space" condition that leads to log space hangs... Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org> |
||
|---|---|---|
| .. | ||
| xfs_ag_resv.c | ||
| xfs_ag_resv.h | ||
| xfs_ag.c | ||
| xfs_ag.h | ||
| xfs_alloc_btree.c | ||
| xfs_alloc_btree.h | ||
| xfs_alloc.c | ||
| xfs_alloc.h | ||
| xfs_attr_leaf.c | ||
| xfs_attr_leaf.h | ||
| xfs_attr_remote.c | ||
| xfs_attr_remote.h | ||
| xfs_attr_sf.h | ||
| xfs_attr.c | ||
| xfs_attr.h | ||
| xfs_bit.c | ||
| xfs_bit.h | ||
| xfs_bmap_btree.c | ||
| xfs_bmap_btree.h | ||
| xfs_bmap.c | ||
| xfs_bmap.h | ||
| xfs_btree_mem.c | ||
| xfs_btree_mem.h | ||
| xfs_btree_staging.c | ||
| xfs_btree_staging.h | ||
| xfs_btree.c | ||
| xfs_btree.h | ||
| xfs_cksum.h | ||
| xfs_da_btree.c | ||
| xfs_da_btree.h | ||
| xfs_da_format.h | ||
| xfs_defer.c | ||
| xfs_defer.h | ||
| xfs_dir2_block.c | ||
| xfs_dir2_data.c | ||
| xfs_dir2_leaf.c | ||
| xfs_dir2_node.c | ||
| xfs_dir2_priv.h | ||
| xfs_dir2_sf.c | ||
| xfs_dir2.c | ||
| xfs_dir2.h | ||
| xfs_dquot_buf.c | ||
| xfs_errortag.h | ||
| xfs_exchmaps.c | ||
| xfs_exchmaps.h | ||
| xfs_format.h | ||
| xfs_fs.h | ||
| xfs_health.h | ||
| xfs_ialloc_btree.c | ||
| xfs_ialloc_btree.h | ||
| xfs_ialloc.c | ||
| xfs_ialloc.h | ||
| xfs_iext_tree.c | ||
| xfs_inode_buf.c | ||
| xfs_inode_buf.h | ||
| xfs_inode_fork.c | ||
| xfs_inode_fork.h | ||
| xfs_inode_util.c | ||
| xfs_inode_util.h | ||
| xfs_log_format.h | ||
| xfs_log_recover.h | ||
| xfs_log_rlimit.c | ||
| xfs_ondisk.h | ||
| xfs_parent.c | ||
| xfs_parent.h | ||
| xfs_quota_defs.h | ||
| xfs_refcount_btree.c | ||
| xfs_refcount_btree.h | ||
| xfs_refcount.c | ||
| xfs_refcount.h | ||
| xfs_rmap_btree.c | ||
| xfs_rmap_btree.h | ||
| xfs_rmap.c | ||
| xfs_rmap.h | ||
| xfs_rtbitmap.c | ||
| xfs_rtbitmap.h | ||
| xfs_sb.c | ||
| xfs_sb.h | ||
| xfs_shared.h | ||
| xfs_symlink_remote.c | ||
| xfs_symlink_remote.h | ||
| xfs_trans_inode.c | ||
| xfs_trans_resv.c | ||
| xfs_trans_resv.h | ||
| xfs_trans_space.c | ||
| xfs_trans_space.h | ||
| xfs_types.c | ||
| xfs_types.h | ||