From: Zhang Yi <yi.zhang@xxxxxxxxxx>
jbd2_transaction_committed() is used to check whether a transaction with
the given tid has already committed, it hold j_state_lock in read mode
and check the tid of current running transaction and committing
transaction, but holding the j_state_lock is expensive.
We have already stored the sequence number of the most recently
committed transaction in journal t->j_commit_sequence, we could do this
check by comparing it with the given tid instead. If the given tid isn't
smaller than j_commit_sequence, we can ensure that the given transaction
has been committed. That way we could drop the expensive lock and
achieve about 10% ~ 20% performance gains in concurrent DIOs on may
virtual machine with 100G ramdisk.
fio -filename=/mnt/foo -direct=1 -iodepth=10 -rw=$rw -ioengine=libaio \
-bs=4k -size=10G -numjobs=10 -runtime=60 -overwrite=1 -name=test \
-group_reporting
Before:
overwrite IOPS=88.2k, BW=344MiB/s
read IOPS=95.7k, BW=374MiB/s
rand overwrite IOPS=98.7k, BW=386MiB/s
randread IOPS=102k, BW=397MiB/s
After:
verwrite: IOPS=105k, BW=410MiB/s
read: IOPS=112k, BW=436MiB/s
rand overwrite: IOPS=104k, BW=404MiB/s
randread: IOPS=111k, BW=432MiB/s
CC: Dave Chinner <david@xxxxxxxxxxxxx>
Suggested-by: Dave Chinner <david@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/linux-ext4/493ab4c5-505c-a351-eefa-7d2677cdf800@xxxxxxxxxxxxxxx/T/#m6a14df5d085527a188c5a151191e87a3252dc4e2
Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
---
fs/ext4/inode.c | 4 ++--
fs/jbd2/journal.c | 17 -----------------
include/linux/jbd2.h | 1 -
3 files changed, 2 insertions(+), 20 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 537803250ca9..e8e2865bf9ac 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3199,8 +3199,8 @@ static bool ext4_inode_datasync_dirty(struct inode *inode)
journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
if (journal) {
- if (jbd2_transaction_committed(journal,
- EXT4_I(inode)->i_datasync_tid))
+ if (tid_geq(journal->j_commit_sequence,
+ EXT4_I(inode)->i_datasync_tid))
return false;
if (test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT))
return !list_empty(&EXT4_I(inode)->i_fc_list);
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index b6c114c11b97..73737cd1106f 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -786,23 +786,6 @@ int jbd2_fc_end_commit_fallback(journal_t *journal)
}
EXPORT_SYMBOL(jbd2_fc_end_commit_fallback);
-/* Return 1 when transaction with given tid has already committed. */
-int jbd2_transaction_committed(journal_t *journal, tid_t tid)
-{
- int ret = 1;
-
- read_lock(&journal->j_state_lock);
- if (journal->j_running_transaction &&
- journal->j_running_transaction->t_tid == tid)
- ret = 0;
- if (journal->j_committing_transaction &&
- journal->j_committing_transaction->t_tid == tid)
- ret = 0;
- read_unlock(&journal->j_state_lock);
- return ret;
-}
-EXPORT_SYMBOL(jbd2_transaction_committed);
-
/*
* When this function returns the transaction corresponding to tid
* will be completed. If the transaction has currently running, start
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 971f3e826e15..e15ae324169d 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1643,7 +1643,6 @@ extern void jbd2_clear_buffer_revoked_flags(journal_t *journal);
int jbd2_log_start_commit(journal_t *journal, tid_t tid);
int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
-int jbd2_transaction_committed(journal_t *journal, tid_t tid);
int jbd2_complete_transaction(journal_t *journal, tid_t tid);
int jbd2_log_do_checkpoint(journal_t *journal);
int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
--
2.39.2
