[PATCH 12/14] xfs: avoid cil push lock if possible

Dave Chinner
2021-11-09T01:52:49Z

Because now it hurts when the CIL fills up.

- 37.20% __xfs_trans_commit
- 35.84% xfs_log_commit_cil
- 19.34% _raw_spin_lock
- do_raw_spin_lock
19.01% __pv_queued_spin_lock_slowpath
- 4.20% xfs_log_ticket_ungrant
0.90% xfs_log_space_wake

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/xfs_log_cil.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index 84924da6396d..3355da50d5c0 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -1299,10 +1299,18 @@ xlog_cil_push_background(
ASSERT(!test_bit(XLOG_CIL_EMPTY, &cil->xc_flags));

/*
- * Don't do a background push if we haven't used up all the
- * space available yet.
+ * We are done if:
+ * - we haven't used up all the space available yet; or
+ * - we've already queued up a push; and
+ * - we're not over the hard limit; and
+ * - nothing has been over the hard limit.
+ *
+ * If so, we don't need to take the push lock as there's nothing to do.
*/
- if (space_used < XLOG_CIL_SPACE_LIMIT(log)) {
+ if (space_used < XLOG_CIL_SPACE_LIMIT(log) ||
+ (cil->xc_push_seq == cil->xc_current_sequence &&
+ space_used < XLOG_CIL_BLOCKING_SPACE_LIMIT(log) &&
+ !waitqueue_active(&cil->xc_push_wait))) {
up_read(&cil->xc_ctx_lock);
return;
}
--
2.33.0