All of lore.kernel.org
 help / color / mirror / Atom feed
From: Dave Chinner <david@fromorbit.com>
To: xfs@oss.sgi.com
Subject: [PATCH 06/14] xfs: convert l_last_sync_lsn to an atomic variable
Date: Mon, 29 Nov 2010 12:38:24 +1100	[thread overview]
Message-ID: <1290994712-21376-7-git-send-email-david@fromorbit.com> (raw)
In-Reply-To: <1290994712-21376-1-git-send-email-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

log->l_last_sync_lsn is updated in only one critical spot - log
buffer Io completion - and is protected by the grant lock here. This
requires the grant lock to be taken for every log buffer IO
completion. Converting the l_last_sync_lsn variable to an atomic64_t
means that we do not need to take the grant lock in log buffer IO
completion to update it.

This also removes the need for explicitly holding a spinlock to read
the l_last_sync_lsn on 32 bit platforms.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log.c         |   57 ++++++++++++++++++++-------------------------
 fs/xfs/xfs_log_priv.h    |    9 ++++++-
 fs/xfs/xfs_log_recover.c |    6 ++--
 3 files changed, 36 insertions(+), 36 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index a35ef8f..90a605cc 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -360,7 +360,7 @@ xfs_log_reserve(
 
 		spin_lock(&log->l_grant_lock);
 		xlog_grant_push_ail(log, log->l_tail_lsn,
-				    log->l_last_sync_lsn,
+				    atomic64_read(&log->l_last_sync_lsn),
 				    internal_ticket->t_unit_res);
 		spin_unlock(&log->l_grant_lock);
 		retval = xlog_regrant_write_log_space(log, internal_ticket);
@@ -378,7 +378,7 @@ xfs_log_reserve(
 
 		spin_lock(&log->l_grant_lock);
 		xlog_grant_push_ail(log, log->l_tail_lsn,
-				    log->l_last_sync_lsn,
+				    atomic64_read(&log->l_last_sync_lsn),
 				    (internal_ticket->t_unit_res *
 				     internal_ticket->t_cnt));
 		spin_unlock(&log->l_grant_lock);
@@ -718,12 +718,8 @@ xfs_log_move_tail(xfs_mount_t	*mp,
 	if (XLOG_FORCED_SHUTDOWN(log))
 		return;
 
-	if (tail_lsn == 0) {
-		/* needed since sync_lsn is 64 bits */
-		spin_lock(&log->l_icloglock);
-		tail_lsn = log->l_last_sync_lsn;
-		spin_unlock(&log->l_icloglock);
-	}
+	if (tail_lsn == 0)
+		tail_lsn = atomic64_read(&log->l_last_sync_lsn);
 
 	spin_lock(&log->l_grant_lock);
 
@@ -845,11 +841,9 @@ xlog_assign_tail_lsn(xfs_mount_t *mp)
 
 	tail_lsn = xfs_trans_ail_tail(mp->m_ail);
 	spin_lock(&log->l_grant_lock);
-	if (tail_lsn != 0) {
-		log->l_tail_lsn = tail_lsn;
-	} else {
-		tail_lsn = log->l_tail_lsn = log->l_last_sync_lsn;
-	}
+	if (!tail_lsn)
+		tail_lsn = atomic64_read(&log->l_last_sync_lsn);
+	log->l_tail_lsn = tail_lsn;
 	spin_unlock(&log->l_grant_lock);
 
 	return tail_lsn;
@@ -1057,10 +1051,9 @@ xlog_alloc_log(xfs_mount_t	*mp,
 	log->l_flags	   |= XLOG_ACTIVE_RECOVERY;
 
 	log->l_prev_block  = -1;
-	log->l_tail_lsn	   = xlog_assign_lsn(1, 0);
-	/* log->l_tail_lsn = 0x100000000LL; cycle = 1; current block = 0 */
-	log->l_last_sync_lsn = log->l_tail_lsn;
 	log->l_curr_cycle  = 1;	    /* 0 is bad since this is initial value */
+	log->l_tail_lsn	   = xlog_assign_lsn(1, 0);
+	atomic64_set(&log->l_last_sync_lsn, log->l_tail_lsn);
 	log->l_grant_reserve_lsn = xlog_assign_lsn(1, 0);
 	log->l_grant_write_lsn = xlog_assign_lsn(1, 0);
 	INIT_LIST_HEAD(&log->l_reserveq);
@@ -2241,7 +2234,7 @@ xlog_state_do_callback(
 				lowest_lsn = xlog_get_lowest_lsn(log);
 				if (lowest_lsn &&
 				    XFS_LSN_CMP(lowest_lsn,
-				    		be64_to_cpu(iclog->ic_header.h_lsn)) < 0) {
+						be64_to_cpu(iclog->ic_header.h_lsn)) < 0) {
 					iclog = iclog->ic_next;
 					continue; /* Leave this iclog for
 						   * another thread */
@@ -2249,23 +2242,21 @@ xlog_state_do_callback(
 
 				iclog->ic_state = XLOG_STATE_CALLBACK;
 
-				spin_unlock(&log->l_icloglock);
 
-				/* l_last_sync_lsn field protected by
-				 * l_grant_lock. Don't worry about iclog's lsn.
-				 * No one else can be here except us.
+				/*
+				 * update the last_sync_lsn before we drop the
+				 * icloglock to ensure we are the only one that
+				 * can update it.
 				 */
-				spin_lock(&log->l_grant_lock);
-				ASSERT(XFS_LSN_CMP(log->l_last_sync_lsn,
-				       be64_to_cpu(iclog->ic_header.h_lsn)) <= 0);
-				log->l_last_sync_lsn =
-					be64_to_cpu(iclog->ic_header.h_lsn);
-				spin_unlock(&log->l_grant_lock);
+				ASSERT(XFS_LSN_CMP(atomic64_read(&log->l_last_sync_lsn),
+					be64_to_cpu(iclog->ic_header.h_lsn)) <= 0);
+				atomic64_set(&log->l_last_sync_lsn,
+					be64_to_cpu(iclog->ic_header.h_lsn));
 
-			} else {
-				spin_unlock(&log->l_icloglock);
+			} else
 				ioerrors++;
-			}
+
+			spin_unlock(&log->l_icloglock);
 
 			/*
 			 * Keep processing entries in the callback list until
@@ -2576,7 +2567,8 @@ redo:
 			list_add_tail(&tic->t_queue, &log->l_reserveq);
 
 		xlog_grant_push_ail(log, log->l_tail_lsn,
-				    log->l_last_sync_lsn, need_bytes);
+				    atomic64_read(&log->l_last_sync_lsn),
+				    need_bytes);
 
 		XFS_STATS_INC(xs_sleep_logspace);
 		trace_xfs_log_grant_sleep(log, tic);
@@ -2683,7 +2675,8 @@ redo:
 		}
 
 		xlog_grant_push_ail(log, log->l_tail_lsn,
-				    log->l_last_sync_lsn, need_bytes);
+				    atomic64_read(&log->l_last_sync_lsn),
+				    need_bytes);
 
 		XFS_STATS_INC(xs_sleep_logspace);
 		trace_xfs_log_regrant_write_sleep(log, tic);
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 6fcee10..97db8a8 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -508,7 +508,6 @@ typedef struct log {
 	spinlock_t		l_icloglock;    /* grab to change iclog state */
 	xfs_lsn_t		l_tail_lsn;     /* lsn of 1st LR with unflushed
 						 * buffers */
-	xfs_lsn_t		l_last_sync_lsn;/* lsn of last LR on disk */
 	int			l_curr_cycle;   /* Cycle number of log writes */
 	int			l_prev_cycle;   /* Cycle number before last
 						 * block increment */
@@ -522,6 +521,14 @@ typedef struct log {
 	xfs_lsn_t		l_grant_reserve_lsn;
 	xfs_lsn_t		l_grant_write_lsn;
 
+	/*
+	 * l_last_sync_lsn is an atomic so it can be set and read without
+	 * needing to hold specific locks. To avoid operations contending with
+	 * other hot objects, place it on a separate cacheline.
+	 */
+	/* lsn of last LR on disk */
+	atomic64_t		l_last_sync_lsn ____cacheline_aligned_in_smp;
+
 	/* The following field are used for debugging; need to hold icloglock */
 #ifdef DEBUG
 	char			*l_iclog_bak[XLOG_MAX_ICLOGS];
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index d8c62f0..2ce7b48 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -926,7 +926,7 @@ xlog_find_tail(
 	if (found == 2)
 		log->l_curr_cycle++;
 	log->l_tail_lsn = be64_to_cpu(rhead->h_tail_lsn);
-	log->l_last_sync_lsn = be64_to_cpu(rhead->h_lsn);
+	atomic64_set(&log->l_last_sync_lsn, be64_to_cpu(rhead->h_lsn));
 	log->l_grant_reserve_lsn = xlog_assign_lsn(log->l_curr_cycle,
 						BBTOB(log->l_curr_block));
 	log->l_grant_write_lsn = xlog_assign_lsn(log->l_curr_cycle,
@@ -978,9 +978,9 @@ xlog_find_tail(
 			log->l_tail_lsn =
 				xlog_assign_lsn(log->l_curr_cycle,
 						after_umount_blk);
-			log->l_last_sync_lsn =
+			atomic64_set(&log->l_last_sync_lsn,
 				xlog_assign_lsn(log->l_curr_cycle,
-						after_umount_blk);
+						after_umount_blk));
 			*tail_blk = after_umount_blk;
 
 			/*
-- 
1.7.2.3

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

  parent reply	other threads:[~2010-11-29  1:37 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-29  1:38 [PATCH 0/14] xfs: grant lock scaling and removal V2 Dave Chinner
2010-11-29  1:38 ` [PATCH 01/14] xfs: convert log grant ticket queues to list heads Dave Chinner
2010-11-30 22:59   ` Christoph Hellwig
2010-11-29  1:38 ` [PATCH 02/14] xfs: clean up log space grant functions Dave Chinner
2010-12-01 12:30   ` Christoph Hellwig
2010-12-02  1:48     ` Dave Chinner
2010-12-02 11:40       ` Christoph Hellwig
2010-12-03  6:45         ` Dave Chinner
2010-11-29  1:38 ` [PATCH 03/14] xfs: convert log grant heads to LSN notation Dave Chinner
2010-12-01 12:42   ` Christoph Hellwig
2010-12-02  1:49     ` Dave Chinner
2010-12-01 13:05   ` Christoph Hellwig
2010-12-02  2:01     ` Dave Chinner
2010-12-02 11:47       ` Christoph Hellwig
2010-11-29  1:38 ` [PATCH 04/14] xfs: use wait queues directly for log grant queues Dave Chinner
2010-12-01 12:34   ` Christoph Hellwig
2010-12-02  2:02     ` Dave Chinner
2010-11-29  1:38 ` [PATCH 05/14] xfs: make AIL tail pushing independent of the grant lock Dave Chinner
2010-12-01 12:45   ` Christoph Hellwig
2010-12-02  2:04     ` Dave Chinner
2010-11-29  1:38 ` Dave Chinner [this message]
2010-12-01 12:54   ` [PATCH 06/14] xfs: convert l_last_sync_lsn to an atomic variable Christoph Hellwig
2010-11-29  1:38 ` [PATCH 07/14] xfs: convert l_tail_lsn " Dave Chinner
2010-12-01 12:56   ` Christoph Hellwig
2010-11-29  1:38 ` [PATCH 08/14] xfs: convert log grant heads to atomic variables Dave Chinner
2010-12-01 12:59   ` Christoph Hellwig
2010-12-02  2:04     ` Dave Chinner
2010-11-29  1:38 ` [PATCH 09/14] xfs: introduce new locks for the log grant ticket wait queues Dave Chinner
2010-12-01 13:12   ` Christoph Hellwig
2010-12-02  2:10     ` Dave Chinner
2010-12-02 11:48       ` Christoph Hellwig
2010-11-29  1:38 ` [PATCH 10/14] xfs: convert grant head manipulations to lockless algorithm Dave Chinner
2010-12-01 13:15   ` Christoph Hellwig
2010-12-02  2:11     ` Dave Chinner
2010-11-29  1:38 ` [PATCH 11/14] xfs: remove log grant lock Dave Chinner
2010-12-01 13:15   ` Christoph Hellwig
2010-11-29  1:38 ` [PATCH 12/14] xfs: kill useless spinlock_destroy macro Dave Chinner
2010-12-01 13:19   ` Christoph Hellwig
2010-11-29  1:38 ` [PATCH 13/14] xfs: replace use of sv_t with waitqueues in the log Dave Chinner
2010-12-01 13:20   ` Christoph Hellwig
2010-11-29  1:38 ` [PATCH 14/14] xfs: remove sv wrappers Dave Chinner
2010-12-01 13:20   ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1290994712-21376-7-git-send-email-david@fromorbit.com \
    --to=david@fromorbit.com \
    --cc=xfs@oss.sgi.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.