jbd2: Improve scalability by not taking j_state_lock in jbd2_journal_stop() (c35a56a0) · Commits · 戴 / test

One of the most contended locks in the jbd2 layer is j_state_lock when running dbench. This is especially true if using the real-time kernel with its "sleeping spinlocks" patch that replaces spinlocks with priority inheriting mutexes --- but it also shows up on large SMP benchmarks. Thanks to John Stultz for pointing this out. Reviewed by Mingming Cao and Jan Kara. Signed-off-by:

"Theodore Ts'o" <tytso@mit.edu>

fs/jbd2/transaction.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -1311,7 +1311,6 @@ int jbd2_journal_stop(handle_t *handle)
		if (handle->h_sync)
		transaction->t_synchronous_commit = 1;
		current->journal_info = NULL;
		spin_lock(&journal->j_state_lock);
		spin_lock(&transaction->t_handle_lock);
		transaction->t_outstanding_credits -= handle->h_buffer_credits;
		transaction->t_updates--;
		@@ -1340,8 +1339,7 @@ int jbd2_journal_stop(handle_t *handle)
		jbd_debug(2, "transaction too old, requesting commit for "
		"handle %p\n", handle);
		/* This is non-blocking */
		__jbd2_log_start_commit(journal, transaction->t_tid);
		spin_unlock(&journal->j_state_lock);
		jbd2_log_start_commit(journal, transaction->t_tid);

		/*
		* Special case: JBD2_SYNC synchronous updates require us
		@@ -1351,7 +1349,6 @@ int jbd2_journal_stop(handle_t *handle)
		err = jbd2_log_wait_commit(journal, tid);
		} else {
		spin_unlock(&transaction->t_handle_lock);
		spin_unlock(&journal->j_state_lock);
		}

		lock_map_release(&handle->h_lockdep_map);

Admin message