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linux-sg2042/fs/xfs/xfs_trans_priv.h

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Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
/*
[XFS] Update license/copyright notices to match the prefered SGI boilerplate. SGI-PV: 913862 SGI-Modid: xfs-linux:xfs-kern:23903a Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 11:58:39 +08:00
* Copyright (c) 2000,2002,2005 Silicon Graphics, Inc.
* All Rights Reserved.
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
*
[XFS] Update license/copyright notices to match the prefered SGI boilerplate. SGI-PV: 913862 SGI-Modid: xfs-linux:xfs-kern:23903a Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 11:58:39 +08:00
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
* published by the Free Software Foundation.
*
[XFS] Update license/copyright notices to match the prefered SGI boilerplate. SGI-PV: 913862 SGI-Modid: xfs-linux:xfs-kern:23903a Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 11:58:39 +08:00
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
*
[XFS] Update license/copyright notices to match the prefered SGI boilerplate. SGI-PV: 913862 SGI-Modid: xfs-linux:xfs-kern:23903a Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 11:58:39 +08:00
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
*/
#ifndef __XFS_TRANS_PRIV_H__
#define __XFS_TRANS_PRIV_H__
struct xfs_log_item;
struct xfs_log_item_desc;
struct xfs_mount;
struct xfs_trans;
xfs: bulk AIL insertion during transaction commit 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>
2010-12-20 09:02:19 +08:00
struct xfs_ail;
struct xfs_log_vec;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
xfs: sync minor header differences needed by userspace. Little things like exported functions, __KERNEL__ protections, and so on that ensure user and kernel shared headers are identical. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-08-12 18:49:31 +08:00
void xfs_trans_init(struct xfs_mount *);
xfs: simplify log item descriptor tracking Currently we track log item descriptor belonging to a transaction using a complex opencoded chunk allocator. This code has been there since day one and seems to work around the lack of an efficient slab allocator. This patch replaces it with dynamically allocated log item descriptors from a dedicated slab pool, linked to the transaction by a linked list. This allows to greatly simplify the log item descriptor tracking to the point where it's just a couple hundred lines in xfs_trans.c instead of a separate file. The external API has also been simplified while we're at it - the xfs_trans_add_item and xfs_trans_del_item functions to add/ delete items from a transaction have been simplified to the bare minium, and the xfs_trans_find_item function is replaced with a direct dereference of the li_desc field. All debug code walking the list of log items in a transaction is down to a simple list_for_each_entry. Note that we could easily use a singly linked list here instead of the double linked list from list.h as the fastpath only does deletion from sequential traversal. But given that we don't have one available as a library function yet I use the list.h functions for simplicity. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Dave Chinner <dchinner@redhat.com>
2010-06-23 16:11:15 +08:00
void xfs_trans_add_item(struct xfs_trans *, struct xfs_log_item *);
void xfs_trans_del_item(struct xfs_log_item *);
xfs: unlock items before allowing the CIL to commit When we commit a transaction using delayed logging, we need to unlock the items in the transaciton before we unlock the CIL context and allow it to be checkpointed. If we unlock them after we release the CIl context lock, the CIL can checkpoint and complete before we free the log items. This breaks stale buffer item unlock and unpin processing as there is an implicit assumption that the unlock will occur before the unpin. Also, some log items need to store the LSN of the transaction commit in the item (inodes and EFIs) and so can race with other transaction completions if we don't prevent the CIL from checkpointing before the unlock occurs. Cc: <stable@kernel.org> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-08-24 09:42:52 +08:00
void xfs_trans_free_items(struct xfs_trans *tp, xfs_lsn_t commit_lsn,
xfs: pass a boolean flag to xfs_trans_free_items The flags value always was 0 or XFS_TRANS_ABORT. Switch to a bool parameter to allow further cleanups. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
2015-06-04 11:47:43 +08:00
bool abort);
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 12:37:18 +08:00
void xfs_trans_unreserve_and_mod_sb(struct xfs_trans *tp);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
xfs: bulk AIL insertion during transaction commit 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>
2010-12-20 09:02:19 +08:00
void xfs_trans_committed_bulk(struct xfs_ail *ailp, struct xfs_log_vec *lv,
xfs_lsn_t commit_lsn, int aborted);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
/*
[XFS] Use a cursor for AIL traversal. To replace the current generation number ensuring sanity of the AIL traversal, replace it with an external cursor that is linked to the AIL. Basically, we store the next item in the cursor whenever we want to drop the AIL lock to do something to the current item. When we regain the lock. the current item may already be free, so we can't reference it, but the next item in the traversal is already held in the cursor. When we move or delete an object, we search all the active cursors and if there is an item match we clear the cursor(s) that point to the object. This forces the traversal to restart transparently. We don't invalidate the cursor on insert because the cursor still points to a valid item. If the intem is inserted between the current item and the cursor it does not matter; the traversal is considered to be past the insertion point so it will be picked up in the next traversal. Hence traversal restarts pretty much disappear altogether with this method of traversal, which should substantially reduce the overhead of pushing on a busy AIL. Version 2 o add restart logic o comment cursor interface o minor cleanups SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32347a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:38:39 +08:00
* AIL traversal cursor.
*
* Rather than using a generation number for detecting changes in the ail, use
* a cursor that is protected by the ail lock. The aild cursor exists in the
* struct xfs_ail, but other traversals can declare it on the stack and link it
* to the ail list.
*
* When an object is deleted from or moved int the AIL, the cursor list is
* searched to see if the object is a designated cursor item. If it is, it is
* deleted from the cursor so that the next time the cursor is used traversal
* will return to the start.
*
* This means a traversal colliding with a removal will cause a restart of the
* list scan, rather than any insertion or deletion anywhere in the list. The
* low bit of the item pointer is set if the cursor has been invalidated so
* that we can tell the difference between invalidation and reaching the end
* of the list to trigger traversal restarts.
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
*/
[XFS] Use a cursor for AIL traversal. To replace the current generation number ensuring sanity of the AIL traversal, replace it with an external cursor that is linked to the AIL. Basically, we store the next item in the cursor whenever we want to drop the AIL lock to do something to the current item. When we regain the lock. the current item may already be free, so we can't reference it, but the next item in the traversal is already held in the cursor. When we move or delete an object, we search all the active cursors and if there is an item match we clear the cursor(s) that point to the object. This forces the traversal to restart transparently. We don't invalidate the cursor on insert because the cursor still points to a valid item. If the intem is inserted between the current item and the cursor it does not matter; the traversal is considered to be past the insertion point so it will be picked up in the next traversal. Hence traversal restarts pretty much disappear altogether with this method of traversal, which should substantially reduce the overhead of pushing on a busy AIL. Version 2 o add restart logic o comment cursor interface o minor cleanups SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32347a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:38:39 +08:00
struct xfs_ail_cursor {
xfs: convert AIL cursors to use struct list_head The list of active AIL cursors uses a roll-your-own linked list with special casing for the AIL push cursor. Simplify this code by replacing the list with standard struct list_head lists, and use a separate list_head to track the active cursors. This allows us to treat the AIL push cursor as a generic cursor rather than as a special case, further simplifying the code. Further, fix the duplicate push cursor initialisation that the special case handling was hiding, and clean up all the comments around the active cursor list handling. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2011-07-18 11:40:18 +08:00
struct list_head list;
[XFS] Use a cursor for AIL traversal. To replace the current generation number ensuring sanity of the AIL traversal, replace it with an external cursor that is linked to the AIL. Basically, we store the next item in the cursor whenever we want to drop the AIL lock to do something to the current item. When we regain the lock. the current item may already be free, so we can't reference it, but the next item in the traversal is already held in the cursor. When we move or delete an object, we search all the active cursors and if there is an item match we clear the cursor(s) that point to the object. This forces the traversal to restart transparently. We don't invalidate the cursor on insert because the cursor still points to a valid item. If the intem is inserted between the current item and the cursor it does not matter; the traversal is considered to be past the insertion point so it will be picked up in the next traversal. Hence traversal restarts pretty much disappear altogether with this method of traversal, which should substantially reduce the overhead of pushing on a busy AIL. Version 2 o add restart logic o comment cursor interface o minor cleanups SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32347a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:38:39 +08:00
struct xfs_log_item *item;
};
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
[XFS] Move AIL pushing into it's own thread When many hundreds to thousands of threads all try to do simultaneous transactions and the log is in a tail-pushing situation (i.e. full), we can get multiple threads walking the AIL list and contending on the AIL lock. The AIL push is, in effect, a simple I/O dispatch algorithm complicated by the ordering constraints placed on it by the transaction subsystem. It really does not need multiple threads to push on it - even when only a single CPU is pushing the AIL, it can push the I/O out far faster that pretty much any disk subsystem can handle. So, to avoid contention problems stemming from multiple list walkers, move the list walk off into another thread and simply provide a "target" to push to. When a thread requires a push, it sets the target and wakes the push thread, then goes to sleep waiting for the required amount of space to become available in the log. This mechanism should also be a lot fairer under heavy load as the waiters will queue in arrival order, rather than queuing in "who completed a push first" order. Also, by moving the pushing to a separate thread we can do more effectively overload detection and prevention as we can keep context from loop iteration to loop iteration. That is, we can push only part of the list each loop and not have to loop back to the start of the list every time we run. This should also help by reducing the number of items we try to lock and/or push items that we cannot move. Note that this patch is not intended to solve the inefficiencies in the AIL structure and the associated issues with extremely large list contents. That needs to be addresses separately; parallel access would cause problems to any new structure as well, so I'm only aiming to isolate the structure from unbounded parallelism here. SGI-PV: 972759 SGI-Modid: xfs-linux-melb:xfs-kern:30371a Signed-off-by: David Chinner <dgc@sgi.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
2008-02-05 09:13:32 +08:00
/*
[XFS] Use a cursor for AIL traversal. To replace the current generation number ensuring sanity of the AIL traversal, replace it with an external cursor that is linked to the AIL. Basically, we store the next item in the cursor whenever we want to drop the AIL lock to do something to the current item. When we regain the lock. the current item may already be free, so we can't reference it, but the next item in the traversal is already held in the cursor. When we move or delete an object, we search all the active cursors and if there is an item match we clear the cursor(s) that point to the object. This forces the traversal to restart transparently. We don't invalidate the cursor on insert because the cursor still points to a valid item. If the intem is inserted between the current item and the cursor it does not matter; the traversal is considered to be past the insertion point so it will be picked up in the next traversal. Hence traversal restarts pretty much disappear altogether with this method of traversal, which should substantially reduce the overhead of pushing on a busy AIL. Version 2 o add restart logic o comment cursor interface o minor cleanups SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32347a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:38:39 +08:00
* Private AIL structures.
*
* Eventually we need to drive the locking in here as well.
[XFS] Move AIL pushing into it's own thread When many hundreds to thousands of threads all try to do simultaneous transactions and the log is in a tail-pushing situation (i.e. full), we can get multiple threads walking the AIL list and contending on the AIL lock. The AIL push is, in effect, a simple I/O dispatch algorithm complicated by the ordering constraints placed on it by the transaction subsystem. It really does not need multiple threads to push on it - even when only a single CPU is pushing the AIL, it can push the I/O out far faster that pretty much any disk subsystem can handle. So, to avoid contention problems stemming from multiple list walkers, move the list walk off into another thread and simply provide a "target" to push to. When a thread requires a push, it sets the target and wakes the push thread, then goes to sleep waiting for the required amount of space to become available in the log. This mechanism should also be a lot fairer under heavy load as the waiters will queue in arrival order, rather than queuing in "who completed a push first" order. Also, by moving the pushing to a separate thread we can do more effectively overload detection and prevention as we can keep context from loop iteration to loop iteration. That is, we can push only part of the list each loop and not have to loop back to the start of the list every time we run. This should also help by reducing the number of items we try to lock and/or push items that we cannot move. Note that this patch is not intended to solve the inefficiencies in the AIL structure and the associated issues with extremely large list contents. That needs to be addresses separately; parallel access would cause problems to any new structure as well, so I'm only aiming to isolate the structure from unbounded parallelism here. SGI-PV: 972759 SGI-Modid: xfs-linux-melb:xfs-kern:30371a Signed-off-by: David Chinner <dgc@sgi.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
2008-02-05 09:13:32 +08:00
*/
[XFS] Allocate the struct xfs_ail Rather than embedding the struct xfs_ail in the struct xfs_mount, allocate it during AIL initialisation. Add a back pointer to the struct xfs_ail so that we can pass around the xfs_ail and still be able to access the xfs_mount if need be. This is th first step involved in isolating the AIL implementation from the surrounding filesystem code. SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32346a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:38:26 +08:00
struct xfs_ail {
struct xfs_mount *xa_mount;
xfs: revert to using a kthread for AIL pushing Currently we have a few issues with the way the workqueue code is used to implement AIL pushing: - it accidentally uses the same workqueue as the syncer action, and thus can be prevented from running if there are enough sync actions active in the system. - it doesn't use the HIGHPRI flag to queue at the head of the queue of work items At this point I'm not confident enough in getting all the workqueue flags and tweaks right to provide a perfectly reliable execution context for AIL pushing, which is the most important piece in XFS to make forward progress when the log fills. Revert back to use a kthread per filesystem which fixes all the above issues at the cost of having a task struct and stack around for each mounted filesystem. In addition this also gives us much better ways to diagnose any issues involving hung AIL pushing and removes a small amount of code. Signed-off-by: Christoph Hellwig <hch@lst.de> Reported-by: Stefan Priebe <s.priebe@profihost.ag> Tested-by: Stefan Priebe <s.priebe@profihost.ag> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Alex Elder <aelder@sgi.com>
2011-10-11 23:14:10 +08:00
struct task_struct *xa_task;
[XFS] Allocate the struct xfs_ail Rather than embedding the struct xfs_ail in the struct xfs_mount, allocate it during AIL initialisation. Add a back pointer to the struct xfs_ail so that we can pass around the xfs_ail and still be able to access the xfs_mount if need be. This is th first step involved in isolating the AIL implementation from the surrounding filesystem code. SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32346a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:38:26 +08:00
struct list_head xa_ail;
xfs_lsn_t xa_target;
xfs: re-enable xfsaild idle mode and fix associated races xfsaild idle mode logic currently leads to a couple hangs: 1.) If xfsaild is rescheduled in during an incremental scan (i.e., tout != 0) and the target has been updated since the previous run, we can hit the new target and go into idle mode with a still populated ail. 2.) A wake up is only issued when the target is pushed forward. The wake up can race with xfsaild if it is currently in the process of entering idle mode, causing future wake up events to be lost. These hangs have been reproduced and verified as fixed by running xfstests 273 in a loop on a slightly modified upstream kernel. The kernel is modified to re-enable idle mode as previously implemented (when count == 0) and with a revert of commit 670ce93f, which includes performance improvements that make this harder to reproduce. The solution, the algorithm for which has been outlined by Dave Chinner, is to modify xfsaild to enter idle mode only when the ail is empty and the push target has not been moved forward since the last push. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ben Myers <bpm@sgi.com>
2012-06-28 18:52:56 +08:00
xfs_lsn_t xa_target_prev;
xfs: convert AIL cursors to use struct list_head The list of active AIL cursors uses a roll-your-own linked list with special casing for the AIL push cursor. Simplify this code by replacing the list with standard struct list_head lists, and use a separate list_head to track the active cursors. This allows us to treat the AIL push cursor as a generic cursor rather than as a special case, further simplifying the code. Further, fix the duplicate push cursor initialisation that the special case handling was hiding, and clean up all the comments around the active cursor list handling. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2011-07-18 11:40:18 +08:00
struct list_head xa_cursors;
[XFS] Move the AIL lock into the struct xfs_ail Bring the ail lock inside the struct xfs_ail. This means the AIL can be entirely manipulated via the struct xfs_ail rather than needing both the struct xfs_mount and the struct xfs_ail. SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32350a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:39:23 +08:00
spinlock_t xa_lock;
xfs: convert the xfsaild threads to a workqueue Similar to the xfssyncd, the per-filesystem xfsaild threads can be converted to a global workqueue and run periodically by delayed works. This makes sense for the AIL pushing because it uses variable timeouts depending on the work that needs to be done. By removing the xfsaild, we simplify the AIL pushing code and remove the need to spread the code to implement the threading and pushing across multiple files. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Alex Elder <aelder@sgi.com>
2011-04-08 10:45:07 +08:00
xfs_lsn_t xa_last_pushed_lsn;
xfs: reduce the number of log forces from tail pushing The AIL push code will issue a log force on ever single push loop that it exits and has encountered pinned items. It doesn't rescan these pinned items until it revisits the AIL from the start. Hence we only need to force the log once per walk from the start of the AIL to the target LSN. This results in numbers like this: xs_push_ail_flush..... 1456 xs_log_force......... 1485 For an 8-way 50M inode create workload - almost all the log forces are coming from the AIL pushing code. Reduce the number of log forces by only forcing the log if the previous walk found pinned buffers. This reduces the numbers to: xs_push_ail_flush..... 665 xs_log_force......... 682 For the same test. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2011-09-30 12:45:03 +08:00
int xa_log_flush;
xfs: on-stack delayed write buffer lists 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>
2012-04-23 13:58:39 +08:00
struct list_head xa_buf_list;
xfs: implement freezing by emptying the AIL Now that we write back all metadata either synchronously or through the AIL we can simply implement metadata freezing in terms of emptying the AIL. The implementation for this is fairly simply and straight-forward: A new routine is added that asks the xfsaild to push the AIL to the end and waits for it to complete and send a wakeup. The routine will then loop if the AIL is not actually empty, and continue to do so until the AIL is compeltely empty. We keep an inode reclaim pass in the freeze process to avoid having memory pressure have to reclaim inodes that require dirtying the filesystem to be reclaimed after the freeze has completed. This means we can also treat unmount in the exact same way as freeze. As an upside we can now remove the radix tree based inode writeback and xfs_unmountfs_writesb. [ Dave Chinner: - Cleaned up commit message. - Added inode reclaim passes back into freeze. - Cleaned up wakeup mechanism to avoid the use of a new sleep counter variable. ] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2012-04-23 13:58:34 +08:00
wait_queue_head_t xa_empty;
[XFS] Allocate the struct xfs_ail Rather than embedding the struct xfs_ail in the struct xfs_mount, allocate it during AIL initialisation. Add a back pointer to the struct xfs_ail so that we can pass around the xfs_ail and still be able to access the xfs_mount if need be. This is th first step involved in isolating the AIL implementation from the surrounding filesystem code. SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32346a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:38:26 +08:00
};
[XFS] Use a cursor for AIL traversal. To replace the current generation number ensuring sanity of the AIL traversal, replace it with an external cursor that is linked to the AIL. Basically, we store the next item in the cursor whenever we want to drop the AIL lock to do something to the current item. When we regain the lock. the current item may already be free, so we can't reference it, but the next item in the traversal is already held in the cursor. When we move or delete an object, we search all the active cursors and if there is an item match we clear the cursor(s) that point to the object. This forces the traversal to restart transparently. We don't invalidate the cursor on insert because the cursor still points to a valid item. If the intem is inserted between the current item and the cursor it does not matter; the traversal is considered to be past the insertion point so it will be picked up in the next traversal. Hence traversal restarts pretty much disappear altogether with this method of traversal, which should substantially reduce the overhead of pushing on a busy AIL. Version 2 o add restart logic o comment cursor interface o minor cleanups SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32347a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:38:39 +08:00
/*
* From xfs_trans_ail.c
*/
xfs: use AIL bulk update function to implement single updates We now have two copies of AIL insert operations that are mostly duplicate functionality. The single log item updates can be implemented via the bulk updates by turning xfs_trans_ail_update() into a simple wrapper. This removes all the duplicate insert functionality and associated helpers. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-12-20 09:34:26 +08:00
void xfs_trans_ail_update_bulk(struct xfs_ail *ailp,
xfs: use a cursor for bulk AIL insertion Delayed logging can insert tens of thousands of log items into the AIL at the same LSN. When the committing of log commit records occur, we can get insertions occurring at an LSN that is not at the end of the AIL. If there are thousands of items in the AIL on the tail LSN, each insertion has to walk the AIL to find the correct place to insert the new item into the AIL. This can consume large amounts of CPU time and block other operations from occurring while the traversals are in progress. To avoid this repeated walk, use a AIL cursor to record where we should be inserting the new items into the AIL without having to repeat the walk. The cursor infrastructure already provides this functionality for push walks, so is a simple extension of existing code. While this will not avoid the initial walk, it will avoid repeating it tens of thousands of times during a single checkpoint commit. This version includes logic improvements from Christoph Hellwig. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2011-07-18 11:40:16 +08:00
struct xfs_ail_cursor *cur,
xfs: use AIL bulk update function to implement single updates We now have two copies of AIL insert operations that are mostly duplicate functionality. The single log item updates can be implemented via the bulk updates by turning xfs_trans_ail_update() into a simple wrapper. This removes all the duplicate insert functionality and associated helpers. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-12-20 09:34:26 +08:00
struct xfs_log_item **log_items, int nr_items,
xfs_lsn_t lsn) __releases(ailp->xa_lock);
xfs: Simplify xfs_ail_min() with list_first_entry_or_null() At xfs_ail_min(), we do check if the AIL list is empty or not before returning the first item in it with list_empty() and list_first_entry(). This can be simplified a bit with a new list operation routine that is the list_first_entry_or_null() which has been introduced by: commit 6d7581e62f8be462440d7b22c6361f7c9fa4902b list: introduce list_first_entry_or_null v2: make xfs_ail_min() as a static inline function and move it to xfs_trans_priv.h as per Dave Chinner's comments. Signed-off-by: Jie Liu <jeff.liu@oracle.com> Reviewed-by: Ben Myers <bpm@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-08-15 13:08:35 +08:00
/*
* Return a pointer to the first item in the AIL. If the AIL is empty, then
* return NULL.
*/
static inline struct xfs_log_item *
xfs_ail_min(
struct xfs_ail *ailp)
{
return list_first_entry_or_null(&ailp->xa_ail, struct xfs_log_item,
li_ail);
}
xfs: use AIL bulk update function to implement single updates We now have two copies of AIL insert operations that are mostly duplicate functionality. The single log item updates can be implemented via the bulk updates by turning xfs_trans_ail_update() into a simple wrapper. This removes all the duplicate insert functionality and associated helpers. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-12-20 09:34:26 +08:00
static inline void
xfs_trans_ail_update(
struct xfs_ail *ailp,
struct xfs_log_item *lip,
xfs_lsn_t lsn) __releases(ailp->xa_lock)
{
xfs: use a cursor for bulk AIL insertion Delayed logging can insert tens of thousands of log items into the AIL at the same LSN. When the committing of log commit records occur, we can get insertions occurring at an LSN that is not at the end of the AIL. If there are thousands of items in the AIL on the tail LSN, each insertion has to walk the AIL to find the correct place to insert the new item into the AIL. This can consume large amounts of CPU time and block other operations from occurring while the traversals are in progress. To avoid this repeated walk, use a AIL cursor to record where we should be inserting the new items into the AIL without having to repeat the walk. The cursor infrastructure already provides this functionality for push walks, so is a simple extension of existing code. While this will not avoid the initial walk, it will avoid repeating it tens of thousands of times during a single checkpoint commit. This version includes logic improvements from Christoph Hellwig. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2011-07-18 11:40:16 +08:00
xfs_trans_ail_update_bulk(ailp, NULL, &lip, 1, lsn);
xfs: use AIL bulk update function to implement single updates We now have two copies of AIL insert operations that are mostly duplicate functionality. The single log item updates can be implemented via the bulk updates by turning xfs_trans_ail_update() into a simple wrapper. This removes all the duplicate insert functionality and associated helpers. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-12-20 09:34:26 +08:00
}
xfs: remove xfs_trans_ail_delete_bulk xfs_iflush_done uses an on-stack variable length array to pass the log items to be deleted to xfs_trans_ail_delete_bulk. On-stack VLAs are a nasty gcc extension that can lead to unbounded stack allocations, but fortunately we can easily avoid them by simply open coding xfs_trans_ail_delete_bulk in xfs_iflush_done, which is the only caller of it except for the single-item xfs_trans_ail_delete. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2017-04-22 02:24:42 +08:00
bool xfs_ail_delete_one(struct xfs_ail *ailp, struct xfs_log_item *lip);
void xfs_trans_ail_delete(struct xfs_ail *ailp, struct xfs_log_item *lip,
int shutdown_type) __releases(ailp->xa_lock);
xfs: use AIL bulk delete function to implement single delete We now have two copies of AIL delete operations that are mostly duplicate functionality. The single log item deletes can be implemented via the bulk updates by turning xfs_trans_ail_delete() into a simple wrapper. This removes all the duplicate delete functionality and associated helpers. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-12-20 09:36:15 +08:00
xfs: add helper to conditionally remove items from the AIL Several areas of code duplicate a pattern where we take the AIL lock, check whether an item is in the AIL and remove it if so. Create a new helper for this pattern and use it where appropriate. Signed-off-by: Brian Foster <bfoster@redhat.com>
2015-08-19 08:01:08 +08:00
static inline void
xfs_trans_ail_remove(
struct xfs_log_item *lip,
int shutdown_type)
{
struct xfs_ail *ailp = lip->li_ailp;
spin_lock(&ailp->xa_lock);
/* xfs_trans_ail_delete() drops the AIL lock */
if (lip->li_flags & XFS_LI_IN_AIL)
xfs_trans_ail_delete(ailp, lip, shutdown_type);
else
spin_unlock(&ailp->xa_lock);
}
xfs: push the AIL from memory reclaim and periodic sync When we are short on memory, we want to expedite the cleaning of dirty objects. Hence when we run short on memory, we need to kick the AIL flushing into action to clean as many dirty objects as quickly as possible. To implement this, sample the lsn of the log item at the head of the AIL and use that as the push target for the AIL flush. Further, we keep items in the AIL that are dirty that are not tracked any other way, so we can get objects sitting in the AIL that don't get written back until the AIL is pushed. Hence to get the filesystem to the idle state, we might need to push the AIL to flush out any remaining dirty objects sitting in the AIL. This requires the same push mechanism as the reclaim push. This patch also renames xfs_trans_ail_tail() to xfs_ail_min_lsn() to match the new xfs_ail_max_lsn() function introduced in this patch. Similarly for xfs_trans_ail_push -> xfs_ail_push. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Alex Elder <aelder@sgi.com>
2011-04-08 10:45:07 +08:00
void xfs_ail_push(struct xfs_ail *, xfs_lsn_t);
void xfs_ail_push_all(struct xfs_ail *);
xfs: implement freezing by emptying the AIL Now that we write back all metadata either synchronously or through the AIL we can simply implement metadata freezing in terms of emptying the AIL. The implementation for this is fairly simply and straight-forward: A new routine is added that asks the xfsaild to push the AIL to the end and waits for it to complete and send a wakeup. The routine will then loop if the AIL is not actually empty, and continue to do so until the AIL is compeltely empty. We keep an inode reclaim pass in the freeze process to avoid having memory pressure have to reclaim inodes that require dirtying the filesystem to be reclaimed after the freeze has completed. This means we can also treat unmount in the exact same way as freeze. As an upside we can now remove the radix tree based inode writeback and xfs_unmountfs_writesb. [ Dave Chinner: - Cleaned up commit message. - Added inode reclaim passes back into freeze. - Cleaned up wakeup mechanism to avoid the use of a new sleep counter variable. ] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2012-04-23 13:58:34 +08:00
void xfs_ail_push_all_sync(struct xfs_ail *);
xfs: allow assigning the tail lsn with the AIL lock held Provide a variant of xlog_assign_tail_lsn that has the AIL lock already held. By doing so we do an additional atomic_read + atomic_set under the lock, which comes down to two instructions. Switch xfs_trans_ail_update_bulk and xfs_trans_ail_delete_bulk to the new version to reduce the number of lock roundtrips, and prepare for a new addition that would require a third lock roundtrip in xfs_trans_ail_delete_bulk. This addition is also the reason for slightly rearranging the conditionals and relying on xfs_log_space_wake for checking that the filesystem has been shut down internally. 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>
2012-04-23 13:58:33 +08:00
struct xfs_log_item *xfs_ail_min(struct xfs_ail *ailp);
xfs: push the AIL from memory reclaim and periodic sync When we are short on memory, we want to expedite the cleaning of dirty objects. Hence when we run short on memory, we need to kick the AIL flushing into action to clean as many dirty objects as quickly as possible. To implement this, sample the lsn of the log item at the head of the AIL and use that as the push target for the AIL flush. Further, we keep items in the AIL that are dirty that are not tracked any other way, so we can get objects sitting in the AIL that don't get written back until the AIL is pushed. Hence to get the filesystem to the idle state, we might need to push the AIL to flush out any remaining dirty objects sitting in the AIL. This requires the same push mechanism as the reclaim push. This patch also renames xfs_trans_ail_tail() to xfs_ail_min_lsn() to match the new xfs_ail_max_lsn() function introduced in this patch. Similarly for xfs_trans_ail_push -> xfs_ail_push. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Alex Elder <aelder@sgi.com>
2011-04-08 10:45:07 +08:00
xfs_lsn_t xfs_ail_min_lsn(struct xfs_ail *ailp);
xfs: use a cursor for bulk AIL insertion Delayed logging can insert tens of thousands of log items into the AIL at the same LSN. When the committing of log commit records occur, we can get insertions occurring at an LSN that is not at the end of the AIL. If there are thousands of items in the AIL on the tail LSN, each insertion has to walk the AIL to find the correct place to insert the new item into the AIL. This can consume large amounts of CPU time and block other operations from occurring while the traversals are in progress. To avoid this repeated walk, use a AIL cursor to record where we should be inserting the new items into the AIL without having to repeat the walk. The cursor infrastructure already provides this functionality for push walks, so is a simple extension of existing code. While this will not avoid the initial walk, it will avoid repeating it tens of thousands of times during a single checkpoint commit. This version includes logic improvements from Christoph Hellwig. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2011-07-18 11:40:16 +08:00
struct xfs_log_item * xfs_trans_ail_cursor_first(struct xfs_ail *ailp,
[XFS] move the AIl traversal over to a consistent interface With the new cursor interface, it makes sense to make all the traversing code use the cursor interface and make the old one go away. This means more of the AIL interfacing is done by passing struct xfs_ail pointers around the place instead of struct xfs_mount pointers. We can replace the use of xfs_trans_first_ail() in xfs_log_need_covered() as it is only checking if the AIL is empty. We can do that with a call to xfs_trans_ail_tail() instead, where a zero LSN returned indicates and empty AIL... SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32348a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:39:00 +08:00
struct xfs_ail_cursor *cur,
xfs_lsn_t lsn);
xfs: use a cursor for bulk AIL insertion Delayed logging can insert tens of thousands of log items into the AIL at the same LSN. When the committing of log commit records occur, we can get insertions occurring at an LSN that is not at the end of the AIL. If there are thousands of items in the AIL on the tail LSN, each insertion has to walk the AIL to find the correct place to insert the new item into the AIL. This can consume large amounts of CPU time and block other operations from occurring while the traversals are in progress. To avoid this repeated walk, use a AIL cursor to record where we should be inserting the new items into the AIL without having to repeat the walk. The cursor infrastructure already provides this functionality for push walks, so is a simple extension of existing code. While this will not avoid the initial walk, it will avoid repeating it tens of thousands of times during a single checkpoint commit. This version includes logic improvements from Christoph Hellwig. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2011-07-18 11:40:16 +08:00
struct xfs_log_item * xfs_trans_ail_cursor_last(struct xfs_ail *ailp,
struct xfs_ail_cursor *cur,
xfs_lsn_t lsn);
struct xfs_log_item * xfs_trans_ail_cursor_next(struct xfs_ail *ailp,
[XFS] Use a cursor for AIL traversal. To replace the current generation number ensuring sanity of the AIL traversal, replace it with an external cursor that is linked to the AIL. Basically, we store the next item in the cursor whenever we want to drop the AIL lock to do something to the current item. When we regain the lock. the current item may already be free, so we can't reference it, but the next item in the traversal is already held in the cursor. When we move or delete an object, we search all the active cursors and if there is an item match we clear the cursor(s) that point to the object. This forces the traversal to restart transparently. We don't invalidate the cursor on insert because the cursor still points to a valid item. If the intem is inserted between the current item and the cursor it does not matter; the traversal is considered to be past the insertion point so it will be picked up in the next traversal. Hence traversal restarts pretty much disappear altogether with this method of traversal, which should substantially reduce the overhead of pushing on a busy AIL. Version 2 o add restart logic o comment cursor interface o minor cleanups SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32347a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:38:39 +08:00
struct xfs_ail_cursor *cur);
xfs: remove unused ail pointer arg from xfs_trans_ail_cursor_done() Signed-off-by: Eric Sandeen <sandeen@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
2014-04-14 17:06:05 +08:00
void xfs_trans_ail_cursor_done(struct xfs_ail_cursor *cur);
[XFS] Use a cursor for AIL traversal. To replace the current generation number ensuring sanity of the AIL traversal, replace it with an external cursor that is linked to the AIL. Basically, we store the next item in the cursor whenever we want to drop the AIL lock to do something to the current item. When we regain the lock. the current item may already be free, so we can't reference it, but the next item in the traversal is already held in the cursor. When we move or delete an object, we search all the active cursors and if there is an item match we clear the cursor(s) that point to the object. This forces the traversal to restart transparently. We don't invalidate the cursor on insert because the cursor still points to a valid item. If the intem is inserted between the current item and the cursor it does not matter; the traversal is considered to be past the insertion point so it will be picked up in the next traversal. Hence traversal restarts pretty much disappear altogether with this method of traversal, which should substantially reduce the overhead of pushing on a busy AIL. Version 2 o add restart logic o comment cursor interface o minor cleanups SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32347a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:38:39 +08:00
[XFS] Allow 64 bit machines to avoid the AIL lock during flushes When copying lsn's from the log item to the inode or dquot flush lsn, we currently grab the AIL lock. We do this because the LSN is a 64 bit quantity and it needs to be read atomically. The lock is used to guarantee atomicity for 32 bit platforms. Make the LSN copying a small function, and make the function used conditional on BITS_PER_LONG so that 64 bit machines don't need to take the AIL lock in these places. SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32349a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:39:12 +08:00
#if BITS_PER_LONG != 64
static inline void
xfs_trans_ail_copy_lsn(
struct xfs_ail *ailp,
xfs_lsn_t *dst,
xfs_lsn_t *src)
{
ASSERT(sizeof(xfs_lsn_t) == 8); /* don't lock if it shrinks */
[XFS] Move the AIL lock into the struct xfs_ail Bring the ail lock inside the struct xfs_ail. This means the AIL can be entirely manipulated via the struct xfs_ail rather than needing both the struct xfs_mount and the struct xfs_ail. SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32350a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:39:23 +08:00
spin_lock(&ailp->xa_lock);
[XFS] Allow 64 bit machines to avoid the AIL lock during flushes When copying lsn's from the log item to the inode or dquot flush lsn, we currently grab the AIL lock. We do this because the LSN is a 64 bit quantity and it needs to be read atomically. The lock is used to guarantee atomicity for 32 bit platforms. Make the LSN copying a small function, and make the function used conditional on BITS_PER_LONG so that 64 bit machines don't need to take the AIL lock in these places. SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32349a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:39:12 +08:00
*dst = *src;
[XFS] Move the AIL lock into the struct xfs_ail Bring the ail lock inside the struct xfs_ail. This means the AIL can be entirely manipulated via the struct xfs_ail rather than needing both the struct xfs_mount and the struct xfs_ail. SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32350a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:39:23 +08:00
spin_unlock(&ailp->xa_lock);
[XFS] Allow 64 bit machines to avoid the AIL lock during flushes When copying lsn's from the log item to the inode or dquot flush lsn, we currently grab the AIL lock. We do this because the LSN is a 64 bit quantity and it needs to be read atomically. The lock is used to guarantee atomicity for 32 bit platforms. Make the LSN copying a small function, and make the function used conditional on BITS_PER_LONG so that 64 bit machines don't need to take the AIL lock in these places. SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32349a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
2008-10-30 14:39:12 +08:00
}
#else
static inline void
xfs_trans_ail_copy_lsn(
struct xfs_ail *ailp,
xfs_lsn_t *dst,
xfs_lsn_t *src)
{
ASSERT(sizeof(xfs_lsn_t) == 8);
*dst = *src;
}
#endif
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
#endif /* __XFS_TRANS_PRIV_H__ */