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From: Dave Chinner <david@fromorbit.com>
To: xfs@oss.sgi.com
Subject: [PATCH 28/34] xfs: make AIL tail pushing independent of the grant lock
Date: Tue, 21 Dec 2010 18:29:24 +1100	[thread overview]
Message-ID: <1292916570-25015-29-git-send-email-david@fromorbit.com> (raw)
In-Reply-To: <1292916570-25015-1-git-send-email-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

The xlog_grant_push_ail() currently takes the grant lock internally to sample
the tail lsn, last sync lsn and the reserve grant head. Most of the callers
already hold the grant lock but have to drop it before calling
xlog_grant_push_ail(). This is a left over from when the AIL tail pushing was
done in line and hence xlog_grant_push_ail had to drop the grant lock. AIL push
is now done in another thread and hence we can safely hold the grant lock over
the entire xlog_grant_push_ail call.

Push the grant lock outside of xlog_grant_push_ail() to simplify the locking
and synchronisation needed for tail pushing.  This will reduce traffic on the
grant lock by itself, but this is only one step in preparing for the complete
removal of the grant lock.

While there, clean up the formatting of xlog_grant_push_ail() to match the
rest of the XFS code.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_log.c |  111 ++++++++++++++++++++++++++---------------------------
 1 files changed, 54 insertions(+), 57 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index cc0504e..1e2020d 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -70,7 +70,7 @@ STATIC void xlog_state_want_sync(xlog_t	*log, xlog_in_core_t *iclog);
 /* local functions to manipulate grant head */
 STATIC int  xlog_grant_log_space(xlog_t		*log,
 				 xlog_ticket_t	*xtic);
-STATIC void xlog_grant_push_ail(xfs_mount_t	*mp,
+STATIC void xlog_grant_push_ail(struct log	*log,
 				int		need_bytes);
 STATIC void xlog_regrant_reserve_log_space(xlog_t	 *log,
 					   xlog_ticket_t *ticket);
@@ -318,7 +318,9 @@ xfs_log_reserve(
 
 		trace_xfs_log_reserve(log, internal_ticket);
 
-		xlog_grant_push_ail(mp, internal_ticket->t_unit_res);
+		spin_lock(&log->l_grant_lock);
+		xlog_grant_push_ail(log, internal_ticket->t_unit_res);
+		spin_unlock(&log->l_grant_lock);
 		retval = xlog_regrant_write_log_space(log, internal_ticket);
 	} else {
 		/* may sleep if need to allocate more tickets */
@@ -332,9 +334,11 @@ xfs_log_reserve(
 
 		trace_xfs_log_reserve(log, internal_ticket);
 
-		xlog_grant_push_ail(mp,
+		spin_lock(&log->l_grant_lock);
+		xlog_grant_push_ail(log,
 				    (internal_ticket->t_unit_res *
 				     internal_ticket->t_cnt));
+		spin_unlock(&log->l_grant_lock);
 		retval = xlog_grant_log_space(log, internal_ticket);
 	}
 
@@ -1185,59 +1189,58 @@ xlog_commit_record(
  * water mark.  In this manner, we would be creating a low water mark.
  */
 STATIC void
-xlog_grant_push_ail(xfs_mount_t	*mp,
-		    int		need_bytes)
+xlog_grant_push_ail(
+	struct log	*log,
+	int		need_bytes)
 {
-    xlog_t	*log = mp->m_log;	/* pointer to the log */
-    xfs_lsn_t	tail_lsn;		/* lsn of the log tail */
-    xfs_lsn_t	threshold_lsn = 0;	/* lsn we'd like to be at */
-    int		free_blocks;		/* free blocks left to write to */
-    int		free_bytes;		/* free bytes left to write to */
-    int		threshold_block;	/* block in lsn we'd like to be at */
-    int		threshold_cycle;	/* lsn cycle we'd like to be at */
-    int		free_threshold;
-
-    ASSERT(BTOBB(need_bytes) < log->l_logBBsize);
-
-    spin_lock(&log->l_grant_lock);
-    free_bytes = xlog_space_left(log, &log->l_grant_reserve_head);
-    tail_lsn = log->l_tail_lsn;
-    free_blocks = BTOBBT(free_bytes);
-
-    /*
-     * Set the threshold for the minimum number of free blocks in the
-     * log to the maximum of what the caller needs, one quarter of the
-     * log, and 256 blocks.
-     */
-    free_threshold = BTOBB(need_bytes);
-    free_threshold = MAX(free_threshold, (log->l_logBBsize >> 2));
-    free_threshold = MAX(free_threshold, 256);
-    if (free_blocks < free_threshold) {
+	xfs_lsn_t	threshold_lsn = 0;
+	xfs_lsn_t	tail_lsn;
+	int		free_blocks;
+	int		free_bytes;
+	int		threshold_block;
+	int		threshold_cycle;
+	int		free_threshold;
+
+	ASSERT(BTOBB(need_bytes) < log->l_logBBsize);
+
+	tail_lsn = log->l_tail_lsn;
+	free_bytes = xlog_space_left(log, &log->l_grant_reserve_head);
+	free_blocks = BTOBBT(free_bytes);
+
+	/*
+	 * Set the threshold for the minimum number of free blocks in the
+	 * log to the maximum of what the caller needs, one quarter of the
+	 * log, and 256 blocks.
+	 */
+	free_threshold = BTOBB(need_bytes);
+	free_threshold = MAX(free_threshold, (log->l_logBBsize >> 2));
+	free_threshold = MAX(free_threshold, 256);
+	if (free_blocks >= free_threshold)
+		return;
+
 	threshold_block = BLOCK_LSN(tail_lsn) + free_threshold;
 	threshold_cycle = CYCLE_LSN(tail_lsn);
 	if (threshold_block >= log->l_logBBsize) {
-	    threshold_block -= log->l_logBBsize;
-	    threshold_cycle += 1;
+		threshold_block -= log->l_logBBsize;
+		threshold_cycle += 1;
 	}
-	threshold_lsn = xlog_assign_lsn(threshold_cycle, threshold_block);
-
-	/* Don't pass in an lsn greater than the lsn of the last
+	threshold_lsn = xlog_assign_lsn(threshold_cycle,
+					threshold_block);
+	/*
+	 * Don't pass in an lsn greater than the lsn of the last
 	 * log record known to be on disk.
 	 */
 	if (XFS_LSN_CMP(threshold_lsn, log->l_last_sync_lsn) > 0)
-	    threshold_lsn = log->l_last_sync_lsn;
-    }
-    spin_unlock(&log->l_grant_lock);
-
-    /*
-     * Get the transaction layer to kick the dirty buffers out to
-     * disk asynchronously. No point in trying to do this if
-     * the filesystem is shutting down.
-     */
-    if (threshold_lsn &&
-	!XLOG_FORCED_SHUTDOWN(log))
-	    xfs_trans_ail_push(log->l_ailp, threshold_lsn);
-}	/* xlog_grant_push_ail */
+		threshold_lsn = log->l_last_sync_lsn;
+
+	/*
+	 * Get the transaction layer to kick the dirty buffers out to
+	 * disk asynchronously. No point in trying to do this if
+	 * the filesystem is shutting down.
+	 */
+	if (!XLOG_FORCED_SHUTDOWN(log))
+		xfs_trans_ail_push(log->l_ailp, threshold_lsn);
+}
 
 /*
  * The bdstrat callback function for log bufs. This gives us a central
@@ -2543,9 +2546,7 @@ redo:
 
 		trace_xfs_log_grant_sleep2(log, tic);
 
-		spin_unlock(&log->l_grant_lock);
-		xlog_grant_push_ail(log->l_mp, need_bytes);
-		spin_lock(&log->l_grant_lock);
+		xlog_grant_push_ail(log, need_bytes);
 
 		XFS_STATS_INC(xs_sleep_logspace);
 		xlog_wait(&tic->t_wait, &log->l_grant_lock);
@@ -2641,9 +2642,7 @@ xlog_regrant_write_log_space(xlog_t	   *log,
 
 			trace_xfs_log_regrant_write_sleep1(log, tic);
 
-			spin_unlock(&log->l_grant_lock);
-			xlog_grant_push_ail(log->l_mp, need_bytes);
-			spin_lock(&log->l_grant_lock);
+			xlog_grant_push_ail(log, need_bytes);
 
 			XFS_STATS_INC(xs_sleep_logspace);
 			xlog_wait(&tic->t_wait, &log->l_grant_lock);
@@ -2666,9 +2665,7 @@ redo:
 	if (free_bytes < need_bytes) {
 		if (list_empty(&tic->t_queue))
 			list_add_tail(&tic->t_queue, &log->l_writeq);
-		spin_unlock(&log->l_grant_lock);
-		xlog_grant_push_ail(log->l_mp, need_bytes);
-		spin_lock(&log->l_grant_lock);
+		xlog_grant_push_ail(log, need_bytes);
 
 		XFS_STATS_INC(xs_sleep_logspace);
 		trace_xfs_log_regrant_write_sleep2(log, tic);
-- 
1.7.2.3

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  parent reply	other threads:[~2010-12-21  7:28 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-21  7:28 [PATCH 00/34] xfs: scalability patchset for 2.6.38 Dave Chinner
2010-12-21  7:28 ` [PATCH 01/34] xfs: provide a inode iolock lockdep class Dave Chinner
2010-12-21 15:15   ` Christoph Hellwig
2010-12-21  7:28 ` [PATCH 02/34] xfs: use KM_NOFS for allocations during attribute list operations Dave Chinner
2010-12-21 15:16   ` Christoph Hellwig
2010-12-21  7:28 ` [PATCH 03/34] lib: percpu counter add unless less than functionality Dave Chinner
2010-12-22  2:20   ` Alex Elder
2010-12-22  3:46     ` Dave Chinner
2010-12-21  7:29 ` [PATCH 04/34] xfs: use generic per-cpu counter infrastructure Dave Chinner
2010-12-21  7:29 ` [PATCH 05/34] xfs: demultiplex xfs_icsb_modify_counters() Dave Chinner
2010-12-21  7:29 ` [PATCH 06/34] xfs: dynamic speculative EOF preallocation Dave Chinner
2010-12-21 15:15   ` Christoph Hellwig
2010-12-21 21:42     ` Dave Chinner
2010-12-21 23:44       ` Dave Chinner
2010-12-22  2:29         ` Alex Elder
2010-12-29 12:56         ` Christoph Hellwig
2010-12-27 14:57   ` Alex Elder
2010-12-27 15:00   ` Alex Elder
2011-01-06 18:16   ` Christoph Hellwig
2010-12-21  7:29 ` [PATCH 07/34] xfs: don't truncate prealloc from frequently accessed inodes Dave Chinner
2010-12-21 16:45   ` Christoph Hellwig
2010-12-21  7:29 ` [PATCH 08/34] xfs: rcu free inodes Dave Chinner
2010-12-21  7:29 ` [PATCH 09/34] xfs: convert inode cache lookups to use RCU locking Dave Chinner
2010-12-21  7:29 ` [PATCH 10/34] xfs: convert pag_ici_lock to a spin lock Dave Chinner
2010-12-21  7:29 ` [PATCH 11/34] xfs: convert xfsbud shrinker to a per-buftarg shrinker Dave Chinner
2010-12-21  7:29 ` [PATCH 12/34] xfs: add a lru to the XFS buffer cache Dave Chinner
2010-12-21  7:29 ` [PATCH 13/34] xfs: connect up buffer reclaim priority hooks Dave Chinner
2010-12-21  7:29 ` [PATCH 14/34] xfs: fix EFI transaction cancellation Dave Chinner
2010-12-21  7:29 ` [PATCH 15/34] xfs: Pull EFI/EFD handling out from under the AIL lock Dave Chinner
2010-12-21  7:29 ` [PATCH 16/34] xfs: clean up xfs_ail_delete() Dave Chinner
2010-12-21  7:29 ` [PATCH 17/34] xfs: bulk AIL insertion during transaction commit Dave Chinner
2010-12-21  7:29 ` [PATCH 18/34] xfs: reduce the number of AIL push wakeups Dave Chinner
2010-12-21  7:29 ` [PATCH 19/34] xfs: consume iodone callback items on buffers as they are processed Dave Chinner
2010-12-21  7:29 ` [PATCH 20/34] xfs: remove all the inodes on a buffer from the AIL in bulk Dave Chinner
2010-12-22  2:20   ` Alex Elder
2010-12-22  3:49     ` Dave Chinner
2010-12-21  7:29 ` [PATCH 22/34] xfs: use AIL bulk delete function to implement single delete Dave Chinner
2010-12-21  7:29 ` [PATCH 23/34] xfs: convert log grant ticket queues to list heads Dave Chinner
2010-12-21  7:29 ` [PATCH 24/34] xfs: fact out common grant head/log tail verification code Dave Chinner
2010-12-21  7:29 ` [PATCH 25/34] xfs: rework log grant space calculations Dave Chinner
2010-12-21  7:29 ` [PATCH 26/34] xfs: combine grant heads into a single 64 bit integer Dave Chinner
2010-12-21  7:29 ` [PATCH 27/34] xfs: use wait queues directly for the log wait queues Dave Chinner
2010-12-21  7:29 ` Dave Chinner [this message]
2010-12-21  7:29 ` [PATCH 29/34] xfs: convert l_last_sync_lsn to an atomic variable Dave Chinner
2010-12-21  7:29 ` [PATCH 30/34] xfs: convert l_tail_lsn " Dave Chinner
2010-12-29 12:52   ` Christoph Hellwig
2010-12-29 15:49   ` Alex Elder
2010-12-21  7:29 ` [PATCH 31/34] xfs: convert log grant heads to atomic variables Dave Chinner
2010-12-21  7:29 ` [PATCH 32/34] xfs: introduce new locks for the log grant ticket wait queues Dave Chinner
2010-12-21  7:29 ` [PATCH 33/34] xfs: convert grant head manipulations to lockless algorithm Dave Chinner
2010-12-21  7:29 ` [PATCH 34/34] xfs: kill useless spinlock_destroy macro Dave Chinner
2010-12-23  1:15 ` [PATCH 00/34] xfs: scalability patchset for 2.6.38 Dave Chinner

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