ext4: add fsync batch tuning knobs
Add new mount options, min_batch_time and max_batch_time, which
controls how long the jbd2 layer should wait for additional filesystem
operations to get batched with a synchronous write transaction.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 74d8729..fd1d755 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -964,6 +964,8 @@
spin_lock_init(&journal->j_state_lock);
journal->j_commit_interval = (HZ * JBD2_DEFAULT_MAX_COMMIT_AGE);
+ journal->j_min_batch_time = 0;
+ journal->j_max_batch_time = 15000; /* 15ms */
/* The journal is marked for error until we succeed with recovery! */
journal->j_flags = JBD2_ABORT;
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 13dcbc9..48c21ba 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1255,8 +1255,10 @@
trans_time = ktime_to_ns(ktime_sub(ktime_get(),
transaction->t_start_time));
+ commit_time = max_t(u64, commit_time,
+ 1000*journal->j_min_batch_time);
commit_time = min_t(u64, commit_time,
- 1000*jiffies_to_usecs(1));
+ 1000*journal->j_max_batch_time);
if (trans_time < commit_time) {
ktime_t expires = ktime_add_ns(ktime_get(),