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-rw-r--r--fs/xfs/linux-2.6/xfs_trace.h2
-rw-r--r--fs/xfs/xfs_log.c139
-rw-r--r--fs/xfs/xfs_log_priv.h16
3 files changed, 97 insertions, 60 deletions
diff --git a/fs/xfs/linux-2.6/xfs_trace.h b/fs/xfs/linux-2.6/xfs_trace.h
index b180e1b..647af2a 100644
--- a/fs/xfs/linux-2.6/xfs_trace.h
+++ b/fs/xfs/linux-2.6/xfs_trace.h
@@ -837,6 +837,7 @@ DEFINE_LOGGRANT_EVENT(xfs_log_grant_sleep1);
DEFINE_LOGGRANT_EVENT(xfs_log_grant_wake1);
DEFINE_LOGGRANT_EVENT(xfs_log_grant_sleep2);
DEFINE_LOGGRANT_EVENT(xfs_log_grant_wake2);
+DEFINE_LOGGRANT_EVENT(xfs_log_grant_wake_up);
DEFINE_LOGGRANT_EVENT(xfs_log_regrant_write_enter);
DEFINE_LOGGRANT_EVENT(xfs_log_regrant_write_exit);
DEFINE_LOGGRANT_EVENT(xfs_log_regrant_write_error);
@@ -844,6 +845,7 @@ DEFINE_LOGGRANT_EVENT(xfs_log_regrant_write_sleep1);
DEFINE_LOGGRANT_EVENT(xfs_log_regrant_write_wake1);
DEFINE_LOGGRANT_EVENT(xfs_log_regrant_write_sleep2);
DEFINE_LOGGRANT_EVENT(xfs_log_regrant_write_wake2);
+DEFINE_LOGGRANT_EVENT(xfs_log_regrant_write_wake_up);
DEFINE_LOGGRANT_EVENT(xfs_log_regrant_reserve_enter);
DEFINE_LOGGRANT_EVENT(xfs_log_regrant_reserve_exit);
DEFINE_LOGGRANT_EVENT(xfs_log_regrant_reserve_sub);
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index a1d7d12..6fcc9d0 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -682,12 +682,12 @@ xfs_log_move_tail(xfs_mount_t *mp,
if (tail_lsn != 1)
atomic64_set(&log->l_tail_lsn, tail_lsn);
- spin_lock(&log->l_grant_lock);
- if (!list_empty(&log->l_writeq)) {
+ if (!list_empty_careful(&log->l_writeq)) {
#ifdef DEBUG
if (log->l_flags & XLOG_ACTIVE_RECOVERY)
panic("Recovery problem");
#endif
+ spin_lock(&log->l_grant_write_lock);
free_bytes = xlog_space_left(log, &log->l_grant_write_head);
list_for_each_entry(tic, &log->l_writeq, t_queue) {
ASSERT(tic->t_flags & XLOG_TIC_PERM_RESERV);
@@ -696,15 +696,18 @@ xfs_log_move_tail(xfs_mount_t *mp,
break;
tail_lsn = 0;
free_bytes -= tic->t_unit_res;
+ trace_xfs_log_regrant_write_wake_up(log, tic);
wake_up(&tic->t_wait);
}
+ spin_unlock(&log->l_grant_write_lock);
}
- if (!list_empty(&log->l_reserveq)) {
+ if (!list_empty_careful(&log->l_reserveq)) {
#ifdef DEBUG
if (log->l_flags & XLOG_ACTIVE_RECOVERY)
panic("Recovery problem");
#endif
+ spin_lock(&log->l_grant_reserve_lock);
free_bytes = xlog_space_left(log, &log->l_grant_reserve_head);
list_for_each_entry(tic, &log->l_reserveq, t_queue) {
if (tic->t_flags & XLOG_TIC_PERM_RESERV)
@@ -715,11 +718,12 @@ xfs_log_move_tail(xfs_mount_t *mp,
break;
tail_lsn = 0;
free_bytes -= need_bytes;
+ trace_xfs_log_grant_wake_up(log, tic);
wake_up(&tic->t_wait);
}
+ spin_unlock(&log->l_grant_reserve_lock);
}
- spin_unlock(&log->l_grant_lock);
-} /* xfs_log_move_tail */
+}
/*
* Determine if we have a transaction that has gone to disk
@@ -1010,6 +1014,8 @@ xlog_alloc_log(xfs_mount_t *mp,
xlog_assign_grant_head(&log->l_grant_write_head, 1, 0);
INIT_LIST_HEAD(&log->l_reserveq);
INIT_LIST_HEAD(&log->l_writeq);
+ spin_lock_init(&log->l_grant_reserve_lock);
+ spin_lock_init(&log->l_grant_write_lock);
error = EFSCORRUPTED;
if (xfs_sb_version_hassector(&mp->m_sb)) {
@@ -2477,6 +2483,18 @@ restart:
*
* Once a ticket gets put onto the reserveq, it will only return after
* the needed reservation is satisfied.
+ *
+ * This function is structured so that it has a lock free fast path. This is
+ * necessary because every new transaction reservation will come through this
+ * path. Hence any lock will be globally hot if we take it unconditionally on
+ * every pass.
+ *
+ * As tickets are only ever moved on and off the reserveq under the
+ * l_grant_reserve_lock, we only need to take that lock if we are going
+ * to add the ticket to the queue and sleep. We can avoid taking the lock if the
+ * ticket was never added to the reserveq because the t_queue list head will be
+ * empty and we hold the only reference to it so it can safely be checked
+ * unlocked.
*/
STATIC int
xlog_grant_log_space(xlog_t *log,
@@ -2490,13 +2508,20 @@ xlog_grant_log_space(xlog_t *log,
panic("grant Recovery problem");
#endif
- /* Is there space or do we need to sleep? */
- spin_lock(&log->l_grant_lock);
-
trace_xfs_log_grant_enter(log, tic);
+ need_bytes = tic->t_unit_res;
+ if (tic->t_flags & XFS_LOG_PERM_RESERV)
+ need_bytes *= tic->t_ocnt;
+
/* something is already sleeping; insert new transaction at end */
- if (!list_empty(&log->l_reserveq)) {
+ if (!list_empty_careful(&log->l_reserveq)) {
+ spin_lock(&log->l_grant_reserve_lock);
+ /* recheck the queue now we are locked */
+ if (list_empty(&log->l_reserveq)) {
+ spin_unlock(&log->l_grant_reserve_lock);
+ goto redo;
+ }
list_add_tail(&tic->t_queue, &log->l_reserveq);
trace_xfs_log_grant_sleep1(log, tic);
@@ -2509,48 +2534,47 @@ xlog_grant_log_space(xlog_t *log,
goto error_return;
XFS_STATS_INC(xs_sleep_logspace);
- xlog_wait(&tic->t_wait, &log->l_grant_lock);
+ xlog_wait(&tic->t_wait, &log->l_grant_reserve_lock);
/*
* If we got an error, and the filesystem is shutting down,
* we'll catch it down below. So just continue...
*/
trace_xfs_log_grant_wake1(log, tic);
- spin_lock(&log->l_grant_lock);
}
- if (tic->t_flags & XFS_LOG_PERM_RESERV)
- need_bytes = tic->t_unit_res*tic->t_ocnt;
- else
- need_bytes = tic->t_unit_res;
redo:
if (XLOG_FORCED_SHUTDOWN(log))
- goto error_return;
+ goto error_return_unlocked;
free_bytes = xlog_space_left(log, &log->l_grant_reserve_head);
if (free_bytes < need_bytes) {
+ spin_lock(&log->l_grant_reserve_lock);
if (list_empty(&tic->t_queue))
list_add_tail(&tic->t_queue, &log->l_reserveq);
trace_xfs_log_grant_sleep2(log, tic);
+ if (XLOG_FORCED_SHUTDOWN(log))
+ goto error_return;
+
xlog_grant_push_ail(log, need_bytes);
XFS_STATS_INC(xs_sleep_logspace);
- xlog_wait(&tic->t_wait, &log->l_grant_lock);
-
- spin_lock(&log->l_grant_lock);
- if (XLOG_FORCED_SHUTDOWN(log))
- goto error_return;
+ xlog_wait(&tic->t_wait, &log->l_grant_reserve_lock);
trace_xfs_log_grant_wake2(log, tic);
-
goto redo;
}
- list_del_init(&tic->t_queue);
+ if (!list_empty(&tic->t_queue)) {
+ spin_lock(&log->l_grant_reserve_lock);
+ list_del_init(&tic->t_queue);
+ spin_unlock(&log->l_grant_reserve_lock);
+ }
/* we've got enough space */
+ spin_lock(&log->l_grant_lock);
xlog_grant_add_space(log, &log->l_grant_reserve_head, need_bytes);
xlog_grant_add_space(log, &log->l_grant_write_head, need_bytes);
trace_xfs_log_grant_exit(log, tic);
@@ -2559,8 +2583,11 @@ redo:
spin_unlock(&log->l_grant_lock);
return 0;
- error_return:
+error_return_unlocked:
+ spin_lock(&log->l_grant_reserve_lock);
+error_return:
list_del_init(&tic->t_queue);
+ spin_unlock(&log->l_grant_reserve_lock);
trace_xfs_log_grant_error(log, tic);
/*
@@ -2570,7 +2597,6 @@ redo:
*/
tic->t_curr_res = 0;
tic->t_cnt = 0; /* ungrant will give back unit_res * t_cnt. */
- spin_unlock(&log->l_grant_lock);
return XFS_ERROR(EIO);
} /* xlog_grant_log_space */
@@ -2578,7 +2604,8 @@ redo:
/*
* Replenish the byte reservation required by moving the grant write head.
*
- *
+ * Similar to xlog_grant_log_space, the function is structured to have a lock
+ * free fast path.
*/
STATIC int
xlog_regrant_write_log_space(xlog_t *log,
@@ -2597,12 +2624,9 @@ xlog_regrant_write_log_space(xlog_t *log,
panic("regrant Recovery problem");
#endif
- spin_lock(&log->l_grant_lock);
-
trace_xfs_log_regrant_write_enter(log, tic);
-
if (XLOG_FORCED_SHUTDOWN(log))
- goto error_return;
+ goto error_return_unlocked;
/* If there are other waiters on the queue then give them a
* chance at logspace before us. Wake up the first waiters,
@@ -2611,8 +2635,10 @@ xlog_regrant_write_log_space(xlog_t *log,
* this transaction.
*/
need_bytes = tic->t_unit_res;
- if (!list_empty(&log->l_writeq)) {
+ if (!list_empty_careful(&log->l_writeq)) {
struct xlog_ticket *ntic;
+
+ spin_lock(&log->l_grant_write_lock);
free_bytes = xlog_space_left(log, &log->l_grant_write_head);
list_for_each_entry(ntic, &log->l_writeq, t_queue) {
ASSERT(ntic->t_flags & XLOG_TIC_PERM_RESERV);
@@ -2627,50 +2653,48 @@ xlog_regrant_write_log_space(xlog_t *log,
struct xlog_ticket, t_queue)) {
if (list_empty(&tic->t_queue))
list_add_tail(&tic->t_queue, &log->l_writeq);
-
trace_xfs_log_regrant_write_sleep1(log, tic);
xlog_grant_push_ail(log, need_bytes);
XFS_STATS_INC(xs_sleep_logspace);
- xlog_wait(&tic->t_wait, &log->l_grant_lock);
-
- /* If we're shutting down, this tic is already
- * off the queue */
- spin_lock(&log->l_grant_lock);
- if (XLOG_FORCED_SHUTDOWN(log))
- goto error_return;
-
+ xlog_wait(&tic->t_wait, &log->l_grant_write_lock);
trace_xfs_log_regrant_write_wake1(log, tic);
- }
+ } else
+ spin_unlock(&log->l_grant_write_lock);
}
redo:
if (XLOG_FORCED_SHUTDOWN(log))
- goto error_return;
+ goto error_return_unlocked;
free_bytes = xlog_space_left(log, &log->l_grant_write_head);
if (free_bytes < need_bytes) {
+ spin_lock(&log->l_grant_write_lock);
if (list_empty(&tic->t_queue))
list_add_tail(&tic->t_queue, &log->l_writeq);
+
+ if (XLOG_FORCED_SHUTDOWN(log))
+ goto error_return;
+
xlog_grant_push_ail(log, need_bytes);
XFS_STATS_INC(xs_sleep_logspace);
trace_xfs_log_regrant_write_sleep2(log, tic);
- xlog_wait(&tic->t_wait, &log->l_grant_lock);
-
- /* If we're shutting down, this tic is already off the queue */
- spin_lock(&log->l_grant_lock);
- if (XLOG_FORCED_SHUTDOWN(log))
- goto error_return;
+ xlog_wait(&tic->t_wait, &log->l_grant_write_lock);
trace_xfs_log_regrant_write_wake2(log, tic);
goto redo;
}
- list_del_init(&tic->t_queue);
+ if (!list_empty(&tic->t_queue)) {
+ spin_lock(&log->l_grant_write_lock);
+ list_del_init(&tic->t_queue);
+ spin_unlock(&log->l_grant_write_lock);
+ }
/* we've got enough space */
+ spin_lock(&log->l_grant_lock);
xlog_grant_add_space(log, &log->l_grant_write_head, need_bytes);
trace_xfs_log_regrant_write_exit(log, tic);
xlog_verify_grant_head(log, 1);
@@ -2679,8 +2703,11 @@ redo:
return 0;
+ error_return_unlocked:
+ spin_lock(&log->l_grant_write_lock);
error_return:
list_del_init(&tic->t_queue);
+ spin_unlock(&log->l_grant_write_lock);
trace_xfs_log_regrant_write_error(log, tic);
/*
@@ -2690,7 +2717,6 @@ redo:
*/
tic->t_curr_res = 0;
tic->t_cnt = 0; /* ungrant will give back unit_res * t_cnt. */
- spin_unlock(&log->l_grant_lock);
return XFS_ERROR(EIO);
} /* xlog_regrant_write_log_space */
@@ -3664,12 +3690,10 @@ xfs_log_force_umount(
xlog_cil_force(log);
/*
- * We must hold both the GRANT lock and the LOG lock,
- * before we mark the filesystem SHUTDOWN and wake
- * everybody up to tell the bad news.
+ * mark the filesystem and the as in a shutdown state and wake
+ * everybody up to tell them the bad news.
*/
spin_lock(&log->l_icloglock);
- spin_lock(&log->l_grant_lock);
mp->m_flags |= XFS_MOUNT_FS_SHUTDOWN;
if (mp->m_sb_bp)
XFS_BUF_DONE(mp->m_sb_bp);
@@ -3694,14 +3718,17 @@ xfs_log_force_umount(
* means we have to wake up everybody queued up on reserveq as well as
* writeq. In addition, we make sure in xlog_{re}grant_log_space that
* we don't enqueue anything once the SHUTDOWN flag is set, and this
- * action is protected by the GRANTLOCK.
+ * action is protected by the grant locks.
*/
+ spin_lock(&log->l_grant_reserve_lock);
list_for_each_entry(tic, &log->l_reserveq, t_queue)
wake_up(&tic->t_wait);
+ spin_unlock(&log->l_grant_reserve_lock);
+ spin_lock(&log->l_grant_write_lock);
list_for_each_entry(tic, &log->l_writeq, t_queue)
wake_up(&tic->t_wait);
- spin_unlock(&log->l_grant_lock);
+ spin_unlock(&log->l_grant_write_lock);
if (!(log->l_iclog->ic_state & XLOG_STATE_IOERROR)) {
ASSERT(!logerror);
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 7619d6a..befb2fc 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -512,10 +512,6 @@ typedef struct log {
/* The following block of fields are changed while holding grant_lock */
spinlock_t l_grant_lock ____cacheline_aligned_in_smp;
- struct list_head l_reserveq;
- struct list_head l_writeq;
- atomic64_t l_grant_reserve_head;
- atomic64_t l_grant_write_head;
/*
* l_last_sync_lsn and l_tail_lsn are atomics so they can be set and
@@ -528,6 +524,18 @@ typedef struct log {
/* lsn of 1st LR with unflushed * buffers */
atomic64_t l_tail_lsn ____cacheline_aligned_in_smp;
+ /*
+ * ticket grant locks, queues and accounting have their own cachlines
+ * as these are quite hot and can be operated on concurrently.
+ */
+ spinlock_t l_grant_reserve_lock ____cacheline_aligned_in_smp;
+ struct list_head l_reserveq;
+ atomic64_t l_grant_reserve_head;
+
+ spinlock_t l_grant_write_lock ____cacheline_aligned_in_smp;
+ struct list_head l_writeq;
+ atomic64_t l_grant_write_head;
+
/* The following field are used for debugging; need to hold icloglock */
#ifdef DEBUG
char *l_iclog_bak[XLOG_MAX_ICLOGS];
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