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WSL2-Linux-Kernel/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 02:20:36 +04:00
/*
[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 06:58:39 +03:00
* 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 02:20:36 +04:00
*
[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 06:58:39 +03:00
* 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 02:20:36 +04:00
* 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 06:58:39 +03:00
* 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 02:20:36 +04:00
*
[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 06:58:39 +03:00
* 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 02:20:36 +04:00
*/
#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;
/*
* From xfs_trans_item.c
*/
struct xfs_log_item_desc *xfs_trans_add_item(struct xfs_trans *,
struct xfs_log_item *);
void xfs_trans_free_item(struct xfs_trans *,
struct xfs_log_item_desc *);
struct xfs_log_item_desc *xfs_trans_find_item(struct xfs_trans *,
struct xfs_log_item *);
struct xfs_log_item_desc *xfs_trans_first_item(struct xfs_trans *);
struct xfs_log_item_desc *xfs_trans_next_item(struct xfs_trans *,
struct xfs_log_item_desc *);
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 08:37:18 +04:00
void xfs_trans_unlock_items(struct xfs_trans *tp, xfs_lsn_t commit_lsn);
void xfs_trans_free_items(struct xfs_trans *tp, xfs_lsn_t commit_lsn,
int flags);
void xfs_trans_item_committed(struct xfs_log_item *lip,
xfs_lsn_t commit_lsn, int aborted);
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 02:20:36 +04:00
/*
[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 09:38:39 +03:00
* 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 02:20:36 +04:00
*/
[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 09:38:39 +03:00
struct xfs_ail_cursor {
struct xfs_ail_cursor *next;
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 02:20:36 +04:00
[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 04:13:32 +03:00
/*
[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 09:38:39 +03:00
* 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 04:13:32 +03:00
*/
[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 09:38:26 +03:00
struct xfs_ail {
struct xfs_mount *xa_mount;
struct list_head xa_ail;
uint xa_gen;
struct task_struct *xa_task;
xfs_lsn_t xa_target;
[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 09:38:39 +03:00
struct xfs_ail_cursor 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 09:39:23 +03:00
spinlock_t xa_lock;
[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 09:38:26 +03:00
};
[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 09:38:39 +03:00
/*
* From xfs_trans_ail.c
*/
[XFS] Finish removing the mount pointer from the AIL API Change all the remaining AIL API functions that are passed struct xfs_mount pointers to pass pointers directly to the struct xfs_ail being used. With this conversion, all external access to the AIL is via the struct xfs_ail. Hence the operation and referencing of the AIL is almost entirely independent of the xfs_mount that is using it - it is now much more tightly tied to the log and the items it is tracking in the log than it is tied to the xfs_mount. SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32353a 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 09:39:58 +03:00
void xfs_trans_ail_update(struct xfs_ail *ailp,
struct xfs_log_item *lip, xfs_lsn_t lsn)
__releases(ailp->xa_lock);
void xfs_trans_ail_delete(struct xfs_ail *ailp,
struct xfs_log_item *lip)
__releases(ailp->xa_lock);
void xfs_trans_ail_push(struct xfs_ail *, xfs_lsn_t);
void xfs_trans_unlocked_item(struct xfs_ail *,
xfs_log_item_t *);
[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 09:38:39 +03:00
[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 09:39:00 +03:00
xfs_lsn_t xfs_trans_ail_tail(struct xfs_ail *ailp);
struct xfs_log_item *xfs_trans_ail_cursor_first(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 09:38:39 +03:00
struct xfs_ail_cursor *cur);
[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 09:39:00 +03:00
void xfs_trans_ail_cursor_done(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 09:38:39 +03:00
struct xfs_ail_cursor *cur);
[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 09:38:26 +03:00
long xfsaild_push(struct xfs_ail *, xfs_lsn_t *);
void xfsaild_wakeup(struct xfs_ail *, xfs_lsn_t);
int xfsaild_start(struct xfs_ail *);
void xfsaild_stop(struct xfs_ail *);
[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 04:13:32 +03:00
[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 09:39:12 +03:00
#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 09:39:23 +03:00
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 09:39:12 +03:00
*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 09:39:23 +03:00
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 09:39:12 +03:00
}
#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 02:20:36 +04:00
#endif /* __XFS_TRANS_PRIV_H__ */