0e57f6a36f
When inserting items into the AIL from the transaction committed callbacks, we take the AIL lock for every single item that is to be inserted. For a CIL checkpoint commit, this can be tens of thousands of individual inserts, yet almost all of the items will be inserted at the same point in the AIL because they have the same index. To reduce the overhead and contention on the AIL lock for such operations, introduce a "bulk insert" operation which allows a list of log items with the same LSN to be inserted in a single operation via a list splice. To do this, we need to pre-sort the log items being committed into a temporary list for insertion. The complexity is that not every log item will end up with the same LSN, and not every item is actually inserted into the AIL. Items that don't match the commit LSN will be inserted and unpinned as per the current one-at-a-time method (relatively rare), while items that are not to be inserted will be unpinned and freed immediately. Items that are to be inserted at the given commit lsn are placed in a temporary array and inserted into the AIL in bulk each time the array fills up. As a result of this, we trade off AIL hold time for a significant reduction in traffic. lock_stat output shows that the worst case hold time is unchanged, but contention from AIL inserts drops by an order of magnitude and the number of lock traversal decreases significantly. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
131 lines
4.1 KiB
C
131 lines
4.1 KiB
C
/*
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* Copyright (c) 2000,2002,2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef __XFS_TRANS_PRIV_H__
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#define __XFS_TRANS_PRIV_H__
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struct xfs_log_item;
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struct xfs_log_item_desc;
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struct xfs_mount;
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struct xfs_trans;
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struct xfs_ail;
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struct xfs_log_vec;
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void xfs_trans_add_item(struct xfs_trans *, struct xfs_log_item *);
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void xfs_trans_del_item(struct xfs_log_item *);
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void xfs_trans_free_items(struct xfs_trans *tp, xfs_lsn_t commit_lsn,
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int flags);
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void xfs_trans_unreserve_and_mod_sb(struct xfs_trans *tp);
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void xfs_trans_committed_bulk(struct xfs_ail *ailp, struct xfs_log_vec *lv,
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xfs_lsn_t commit_lsn, int aborted);
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/*
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* AIL traversal cursor.
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*
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* Rather than using a generation number for detecting changes in the ail, use
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* a cursor that is protected by the ail lock. The aild cursor exists in the
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* struct xfs_ail, but other traversals can declare it on the stack and link it
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* to the ail list.
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*
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* When an object is deleted from or moved int the AIL, the cursor list is
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* searched to see if the object is a designated cursor item. If it is, it is
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* deleted from the cursor so that the next time the cursor is used traversal
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* will return to the start.
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*
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* This means a traversal colliding with a removal will cause a restart of the
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* list scan, rather than any insertion or deletion anywhere in the list. The
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* low bit of the item pointer is set if the cursor has been invalidated so
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* that we can tell the difference between invalidation and reaching the end
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* of the list to trigger traversal restarts.
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*/
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struct xfs_ail_cursor {
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struct xfs_ail_cursor *next;
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struct xfs_log_item *item;
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};
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/*
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* Private AIL structures.
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*
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* Eventually we need to drive the locking in here as well.
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*/
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struct xfs_ail {
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struct xfs_mount *xa_mount;
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struct list_head xa_ail;
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uint xa_gen;
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struct task_struct *xa_task;
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xfs_lsn_t xa_target;
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struct xfs_ail_cursor xa_cursors;
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spinlock_t xa_lock;
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};
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/*
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* From xfs_trans_ail.c
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*/
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void xfs_trans_ail_update(struct xfs_ail *ailp,
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struct xfs_log_item *lip, xfs_lsn_t lsn)
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__releases(ailp->xa_lock);
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void xfs_trans_ail_update_bulk(struct xfs_ail *ailp,
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struct xfs_log_item **log_items,
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int nr_items, xfs_lsn_t lsn)
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__releases(ailp->xa_lock);
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void xfs_trans_ail_delete(struct xfs_ail *ailp,
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struct xfs_log_item *lip)
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__releases(ailp->xa_lock);
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void xfs_trans_ail_push(struct xfs_ail *, xfs_lsn_t);
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void xfs_trans_unlocked_item(struct xfs_ail *,
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xfs_log_item_t *);
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xfs_lsn_t xfs_trans_ail_tail(struct xfs_ail *ailp);
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struct xfs_log_item *xfs_trans_ail_cursor_first(struct xfs_ail *ailp,
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struct xfs_ail_cursor *cur,
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xfs_lsn_t lsn);
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struct xfs_log_item *xfs_trans_ail_cursor_next(struct xfs_ail *ailp,
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struct xfs_ail_cursor *cur);
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void xfs_trans_ail_cursor_done(struct xfs_ail *ailp,
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struct xfs_ail_cursor *cur);
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long xfsaild_push(struct xfs_ail *, xfs_lsn_t *);
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void xfsaild_wakeup(struct xfs_ail *, xfs_lsn_t);
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int xfsaild_start(struct xfs_ail *);
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void xfsaild_stop(struct xfs_ail *);
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#if BITS_PER_LONG != 64
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static inline void
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xfs_trans_ail_copy_lsn(
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struct xfs_ail *ailp,
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xfs_lsn_t *dst,
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xfs_lsn_t *src)
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{
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ASSERT(sizeof(xfs_lsn_t) == 8); /* don't lock if it shrinks */
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spin_lock(&ailp->xa_lock);
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*dst = *src;
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spin_unlock(&ailp->xa_lock);
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}
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#else
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static inline void
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xfs_trans_ail_copy_lsn(
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struct xfs_ail *ailp,
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xfs_lsn_t *dst,
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xfs_lsn_t *src)
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{
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ASSERT(sizeof(xfs_lsn_t) == 8);
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*dst = *src;
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}
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#endif
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#endif /* __XFS_TRANS_PRIV_H__ */
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