diff options
| author | Jan Kara <jack@suse.cz> | 2014-09-18 00:42:16 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2014-09-18 00:42:16 -0400 |
| commit | cc97f1a7c7eed970e674b84be0e68f479c80228d (patch) | |
| tree | 43d4358c0792994358968b8d1dc2ebef654ba396 | |
| parent | 844749764b416ee2c4ba2da328c04eaad7388242 (diff) | |
| download | linux-cc97f1a7c7eed970e674b84be0e68f479c80228d.tar.bz2 | |
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). The workload can be generated by:
fs_mark -d /fs/ram0/1 -D 2 -N 2560 -n 1000000 -L 1 -S 1 -s 4096
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-and-tested-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/jbd2/checkpoint.c | 32 |
1 files changed, 18 insertions, 14 deletions
diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c index 1fbf59938cc0..3ab4c5ee12ce 100644 --- a/fs/jbd2/checkpoint.c +++ b/fs/jbd2/checkpoint.c @@ -420,7 +420,6 @@ 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) */ @@ -440,12 +439,12 @@ 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 @@ -465,7 +464,6 @@ 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) */ @@ -473,7 +471,8 @@ 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; @@ -485,17 +484,21 @@ 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 @@ -503,11 +506,12 @@ 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; } /* |