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 <[email protected]> Signed-off-by: Jan Kara <[email protected]> --- 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 ------------------------------------------------------------------------------ Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://pubads.g.doubleclick.net/gampad/clk?id=154622311&iu=/4140/ostg.clktrk _______________________________________________ Jfs-discussion mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/jfs-discussion
