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authorHarshad Shirwadkar <harshadshirwadkar@gmail.com>2020-11-06 06:58:59 +0300
committerTheodore Ts'o <tytso@mit.edu>2020-11-07 07:01:03 +0300
commitcc80586a57f704f806b9a1b99a21cd07e37dbedc (patch)
tree4e6d66192c9d1c2fbe46e812023c41e16283f340 /fs
parent0bce577bf9cae13ae32d391432d0030e3f67fc1d (diff)
downloadlinux-cc80586a57f704f806b9a1b99a21cd07e37dbedc.tar.xz
jbd2: add todo for a fast commit performance optimization
Fast commit performance can be optimized if commit thread doesn't wait for ongoing fast commits to complete until the transaction enters T_FLUSH state. Document this optimization. Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com> Link: https://lore.kernel.org/r/20201106035911.1942128-11-harshadshirwadkar@gmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs')
-rw-r--r--fs/jbd2/commit.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index ec516490cb35..b121d7d434c6 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -450,6 +450,15 @@ void jbd2_journal_commit_transaction(journal_t *journal)
schedule();
write_lock(&journal->j_state_lock);
finish_wait(&journal->j_fc_wait, &wait);
+ /*
+ * TODO: by blocking fast commits here, we are increasing
+ * fsync() latency slightly. Strictly speaking, we don't need
+ * to block fast commits until the transaction enters T_FLUSH
+ * state. So an optimization is possible where we block new fast
+ * commits here and wait for existing ones to complete
+ * just before we enter T_FLUSH. That way, the existing fast
+ * commits and this full commit can proceed parallely.
+ */
}
write_unlock(&journal->j_state_lock);