jbd2: don't hold j_state_lock while calling wake_up() (3469a32a) · Commits · 戴 / test

The j_state_lock is one of the hottest locks in the jbd2 layer and thus one of its scalability bottlenecks. We don't need to be holding the j_state_lock while we are calling wake_up(&journal->j_wait_commit), so release the lock a little bit earlier. Signed-off-by:

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

fs/jbd2/journal.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -302,8 +302,8 @@ static void journal_kill_thread(journal_t *journal)
		journal->j_flags \|= JBD2_UNMOUNT;

		while (journal->j_task) {
		wake_up(&journal->j_wait_commit);
		write_unlock(&journal->j_state_lock);
		wake_up(&journal->j_wait_commit);
		wait_event(journal->j_wait_done_commit, journal->j_task == NULL);
		write_lock(&journal->j_state_lock);
		}
		@@ -710,8 +710,8 @@ int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
		while (tid_gt(tid, journal->j_commit_sequence)) {
		jbd_debug(1, "JBD2: want %d, j_commit_sequence=%d\n",
		tid, journal->j_commit_sequence);
		wake_up(&journal->j_wait_commit);
		read_unlock(&journal->j_state_lock);
		wake_up(&journal->j_wait_commit);
		wait_event(journal->j_wait_done_commit,
		!tid_gt(tid, journal->j_commit_sequence));
		read_lock(&journal->j_state_lock);

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