Commit e7b04ac0 authored Jan 30, 2013 by Eric Sandeen Committed by Theodore Ts'o Jan 30, 2013

jbd2: don't wake kjournald unnecessarily



Don't send an extra wakeup to kjournald in the case where we
already have the proper target in j_commit_request, i.e. that
transaction has already been requested for commit.

commit deeeaf13 "jbd2: fix fsync() tid wraparound bug" changed
the logic leading to a wakeup, but it caused some extra wakeups
which were found to lead to a measurable performance regression.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
[tytso@mit.edu: reworked check to make it clearer]
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

parent 091e26df

fs/jbd2/journal.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -513,6 +513,10 @@ int __jbd2_log_space_left(journal_t *journal)
		*/
		int __jbd2_log_start_commit(journal_t *journal, tid_t target)
		{
		/* Return if the txn has already requested to be committed */
		if (journal->j_commit_request == target)
		return 0;

		/*
		* The only transaction we can possibly wait upon is the
		* currently running transaction (if it exists). Otherwise,