Commit 7e2fb2d7 authored Dec 18, 2012 by Eric Sandeen Committed by Jan Kara Jan 14, 2013

jbd: 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
commit has already been requested for commit.

commit d9b01934 "jbd: 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>
Signed-off-by: Jan Kara <jack@suse.cz>

parent b719f430

fs/jbd/journal.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -446,7 +446,8 @@ int __log_start_commit(journal_t *journal, tid_t target)
		* currently running transaction (if it exists). Otherwise,
		* the target tid must be an old one.
		*/
		if (journal->j_running_transaction &&
		if (journal->j_commit_request != target &&
		journal->j_running_transaction &&
		journal->j_running_transaction->t_tid == target) {
		/*
		* We want a new commit: OK, mark the request and wakeup the

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