From 475e1be393ffd3c5d4bf92738a16c391b8e808a2 Mon Sep 17 00:00:00 2001 From: Zhang Yi Date: Mon, 20 May 2024 21:55:48 +0800 Subject: [PATCH] jbd2: speed up jbd2_transaction_committed() commit 7c73ddb7589fb8ddb1136b6306dfb72089c81511 upstream. jbd2_transaction_committed() is used to check whether a transaction with the given tid has already committed, it holds 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: overwrite 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 Suggested-by: Dave Chinner Link: https://lore.kernel.org/linux-ext4/ZjILCPNZRHeazSqV@dread.disaster.area/ Signed-off-by: huwentao --- fs/jbd2/commit.c | 2 +- fs/jbd2/journal.c | 12 +----------- 2 files changed, 2 insertions(+), 12 deletions(-) diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 7bd4b1d4224e..a93ce76b13ee 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -1099,7 +1099,7 @@ restart_loop: commit_transaction->t_state = T_COMMIT_CALLBACK; J_ASSERT(commit_transaction == journal->j_committing_transaction); - journal->j_commit_sequence = commit_transaction->t_tid; + WRITE_ONCE(journal->j_commit_sequence, commit_transaction->t_tid); journal->j_committing_transaction = NULL; commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time)); diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index b7c5819bfc41..7e4dd64464a3 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -717,17 +717,7 @@ int jbd2_log_wait_commit(journal_t *journal, tid_t tid) /* 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; + return tid_geq(READ_ONCE(journal->j_commit_sequence), tid); } EXPORT_SYMBOL(jbd2_transaction_committed);