43ff2122e6
Queue delwri buffers on a local on-stack list instead of a per-buftarg one, and write back the buffers per-process instead of by waking up xfsbufd. This is now easily doable given that we have very few places left that write delwri buffers: - log recovery: Only done at mount time, and already forcing out the buffers synchronously using xfs_flush_buftarg - quotacheck: Same story. - dquot reclaim: Writes out dirty dquots on the LRU under memory pressure. We might want to look into doing more of this via xfsaild, but it's already more optimal than the synchronous inode reclaim that writes each buffer synchronously. - xfsaild: This is the main beneficiary of the change. By keeping a local list of buffers to write we reduce latency of writing out buffers, and more importably we can remove all the delwri list promotions which were hitting the buffer cache hard under sustained metadata loads. The implementation is very straight forward - xfs_buf_delwri_queue now gets a new list_head pointer that it adds the delwri buffers to, and all callers need to eventually submit the list using xfs_buf_delwi_submit or xfs_buf_delwi_submit_nowait. Buffers that already are on a delwri list are skipped in xfs_buf_delwri_queue, assuming they already are on another delwri list. The biggest change to pass down the buffer list was done to the AIL pushing. Now that we operate on buffers the trylock, push and pushbuf log item methods are merged into a single push routine, which tries to lock the item, and if possible add the buffer that needs writeback to the buffer list. This leads to much simpler code than the previous split but requires the individual IOP_PUSH instances to unlock and reacquire the AIL around calls to blocking routines. Given that xfsailds now also handle writing out buffers, the conditions for log forcing and the sleep times needed some small changes. The most important one is that we consider an AIL busy as long we still have buffers to push, and the other one is that we do increment the pushed LSN for buffers that are under flushing at this moment, but still count them towards the stuck items for restart purposes. Without this we could hammer on stuck items without ever forcing the log and not make progress under heavy random delete workloads on fast flash storage devices. [ Dave Chinner: - rebase on previous patches. - improved comments for XBF_DELWRI_Q handling - fix XBF_ASYNC handling in queue submission (test 106 failure) - rename delwri submit function buffer list parameters for clarity - xfs_efd_item_push() should return XFS_ITEM_PINNED ] Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
146 lines
4.4 KiB
C
146 lines
4.4 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 list_head list;
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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 task_struct *xa_task;
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struct list_head xa_ail;
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xfs_lsn_t xa_target;
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struct list_head xa_cursors;
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spinlock_t xa_lock;
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xfs_lsn_t xa_last_pushed_lsn;
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int xa_log_flush;
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struct list_head xa_buf_list;
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wait_queue_head_t xa_empty;
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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_bulk(struct xfs_ail *ailp,
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struct xfs_ail_cursor *cur,
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struct xfs_log_item **log_items, int nr_items,
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xfs_lsn_t lsn) __releases(ailp->xa_lock);
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static inline void
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xfs_trans_ail_update(
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struct xfs_ail *ailp,
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struct xfs_log_item *lip,
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xfs_lsn_t lsn) __releases(ailp->xa_lock)
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{
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xfs_trans_ail_update_bulk(ailp, NULL, &lip, 1, lsn);
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}
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void xfs_trans_ail_delete_bulk(struct xfs_ail *ailp,
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struct xfs_log_item **log_items, int nr_items)
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__releases(ailp->xa_lock);
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static inline void
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xfs_trans_ail_delete(
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struct xfs_ail *ailp,
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xfs_log_item_t *lip) __releases(ailp->xa_lock)
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{
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xfs_trans_ail_delete_bulk(ailp, &lip, 1);
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}
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void xfs_ail_push(struct xfs_ail *, xfs_lsn_t);
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void xfs_ail_push_all(struct xfs_ail *);
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void xfs_ail_push_all_sync(struct xfs_ail *);
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struct xfs_log_item *xfs_ail_min(struct xfs_ail *ailp);
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xfs_lsn_t xfs_ail_min_lsn(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_last(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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#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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