>From ee5a1b87e267a8ae8935952c3c6971fa6cc41c63 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 16 Sep 2014 12:25:20 +0200 Subject: [PATCH 1/2] jbd2: Avoid pointless scanning of checkpoint lists Yuanhan has reported that when he is running fsync(2) heavy workload creating new files over ramdisk, significant amount of time is spent in __jbd2_journal_clean_checkpoint_list() trying to clean old transactions (but they cannot be cleaned up because flusher hasn't yet checkpointed those buffers). Reduce the amount of scanning by stopping to scan the transaction list once we find a transaction that cannot be checkpointed. Note that this way of cleaning is still enough to keep freeing space in the journal after fully checkpointed transactions. Reported-by: Yuanhan Liu Signed-off-by: Jan Kara --- fs/jbd2/checkpoint.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c index 7f34f4716165..e39b2d0e1079 100644 --- a/fs/jbd2/checkpoint.c +++ b/fs/jbd2/checkpoint.c @@ -478,7 +478,6 @@ int jbd2_cleanup_journal_tail(journal_t *journal) * Find all the written-back checkpoint buffers in the given list and * release them. * - * Called with the journal locked. * Called with j_list_lock held. * Returns number of buffers reaped (for debug) */ @@ -498,12 +497,12 @@ static int journal_clean_one_cp_list(struct journal_head *jh, int *released) jh = next_jh; next_jh = jh->b_cpnext; ret = __try_to_free_cp_buf(jh); - if (ret) { - freed++; - if (ret == 2) { - *released = 1; - return freed; - } + if (!ret) + return freed; + freed++; + if (ret == 2) { + *released = 1; + return freed; } /* * This function only frees up some memory @@ -523,7 +522,6 @@ static int journal_clean_one_cp_list(struct journal_head *jh, int *released) * * Find all the written-back checkpoint buffers in the journal and release them. * - * Called with the journal locked. * Called with j_list_lock held. * Returns number of buffers reaped (for debug) */ @@ -531,7 +529,8 @@ static int journal_clean_one_cp_list(struct journal_head *jh, int *released) int __jbd2_journal_clean_checkpoint_list(journal_t *journal) { transaction_t *transaction, *last_transaction, *next_transaction; - int ret = 0; + int ret; + int freed = 0; int released; transaction = journal->j_checkpoint_transactions; @@ -543,17 +542,21 @@ int __jbd2_journal_clean_checkpoint_list(journal_t *journal) do { transaction = next_transaction; next_transaction = transaction->t_cpnext; - ret += journal_clean_one_cp_list(transaction-> + ret = journal_clean_one_cp_list(transaction-> t_checkpoint_list, &released); /* * This function only frees up some memory if possible so we * dont have an obligation to finish processing. Bail out if * preemption requested: */ - if (need_resched()) + if (need_resched()) { + freed += ret; goto out; - if (released) + } + if (released) { + freed += ret; continue; + } /* * It is essential that we are as careful as in the case of * t_checkpoint_list with removing the buffer from the list as @@ -561,11 +564,12 @@ int __jbd2_journal_clean_checkpoint_list(journal_t *journal) */ ret += journal_clean_one_cp_list(transaction-> t_checkpoint_io_list, &released); - if (need_resched()) + freed += ret; + if (need_resched() || !ret) goto out; } while (transaction != last_transaction); out: - return ret; + return freed; } /* -- 1.8.1.4