diff options
| -rw-r--r-- | fs/jbd2/commit.c | 14 | ||||
| -rw-r--r-- | fs/jbd2/transaction.c | 58 | ||||
| -rw-r--r-- | include/linux/jbd2.h | 15 |
3 files changed, 73 insertions, 14 deletions
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 6393fd0..f22d182 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -355,6 +355,8 @@ void jbd2_journal_commit_transaction(journal_t *journal) int flags; int err; unsigned long long blocknr; + ktime_t start_time; + u64 commit_time; char *tagp = NULL; journal_header_t *header; journal_block_tag_t *tag = NULL; @@ -481,6 +483,7 @@ void jbd2_journal_commit_transaction(journal_t *journal) commit_transaction->t_state = T_FLUSH; journal->j_committing_transaction = commit_transaction; journal->j_running_transaction = NULL; + start_time = ktime_get(); commit_transaction->t_log_start = journal->j_head; wake_up(&journal->j_wait_transaction_locked); spin_unlock(&journal->j_state_lock); @@ -995,6 +998,17 @@ restart_loop: J_ASSERT(commit_transaction == journal->j_committing_transaction); journal->j_commit_sequence = commit_transaction->t_tid; journal->j_committing_transaction = NULL; + commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time)); + + /* + * weight the commit time higher than the average time so we don't + * react too strongly to vast changes in the commit time + */ + if (likely(journal->j_average_commit_time)) + journal->j_average_commit_time = (commit_time + + journal->j_average_commit_time*3) / 4; + else + journal->j_average_commit_time = commit_time; spin_unlock(&journal->j_state_lock); if (journal->j_commit_callback) diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index 39b7805..13dcbc9 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -25,6 +25,7 @@ #include <linux/timer.h> #include <linux/mm.h> #include <linux/highmem.h> +#include <linux/hrtimer.h> static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh); @@ -48,6 +49,7 @@ jbd2_get_transaction(journal_t *journal, transaction_t *transaction) { transaction->t_journal = journal; transaction->t_state = T_RUNNING; + transaction->t_start_time = ktime_get(); transaction->t_tid = journal->j_transaction_sequence++; transaction->t_expires = jiffies + journal->j_commit_interval; spin_lock_init(&transaction->t_handle_lock); @@ -1193,7 +1195,7 @@ int jbd2_journal_stop(handle_t *handle) { transaction_t *transaction = handle->h_transaction; journal_t *journal = transaction->t_journal; - int old_handle_count, err; + int err; pid_t pid; J_ASSERT(journal_current_handle() == handle); @@ -1216,24 +1218,52 @@ int jbd2_journal_stop(handle_t *handle) /* * Implement synchronous transaction batching. If the handle * was synchronous, don't force a commit immediately. Let's - * yield and let another thread piggyback onto this transaction. - * Keep doing that while new threads continue to arrive. - * It doesn't cost much - we're about to run a commit and sleep - * on IO anyway. Speeds up many-threaded, many-dir operations - * by 30x or more... + * yield and let another thread piggyback onto this + * transaction. Keep doing that while new threads continue to + * arrive. It doesn't cost much - we're about to run a commit + * and sleep on IO anyway. Speeds up many-threaded, many-dir + * operations by 30x or more... + * + * We try and optimize the sleep time against what the + * underlying disk can do, instead of having a static sleep + * time. This is useful for the case where our storage is so + * fast that it is more optimal to go ahead and force a flush + * and wait for the transaction to be committed than it is to + * wait for an arbitrary amount of time for new writers to + * join the transaction. We achieve this by measuring how + * long it takes to commit a transaction, and compare it with + * how long this transaction has been running, and if run time + * < commit time then we sleep for the delta and commit. This + * greatly helps super fast disks that would see slowdowns as + * more threads started doing fsyncs. * - * But don't do this if this process was the most recent one to - * perform a synchronous write. We do this to detect the case where a - * single process is doing a stream of sync writes. No point in waiting - * for joiners in that case. + * But don't do this if this process was the most recent one + * to perform a synchronous write. We do this to detect the + * case where a single process is doing a stream of sync + * writes. No point in waiting for joiners in that case. */ pid = current->pid; if (handle->h_sync && journal->j_last_sync_writer != pid) { + u64 commit_time, trans_time; + journal->j_last_sync_writer = pid; - do { - old_handle_count = transaction->t_handle_count; - schedule_timeout_uninterruptible(1); - } while (old_handle_count != transaction->t_handle_count); + + spin_lock(&journal->j_state_lock); + commit_time = journal->j_average_commit_time; + spin_unlock(&journal->j_state_lock); + + trans_time = ktime_to_ns(ktime_sub(ktime_get(), + transaction->t_start_time)); + + commit_time = min_t(u64, commit_time, + 1000*jiffies_to_usecs(1)); + + if (trans_time < commit_time) { + ktime_t expires = ktime_add_ns(ktime_get(), + commit_time); + set_current_state(TASK_UNINTERRUPTIBLE); + schedule_hrtimeout(&expires, HRTIMER_MODE_ABS); + } } current->journal_info = NULL; diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index f366457..ab8cef1 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -638,6 +638,11 @@ struct transaction_s unsigned long t_expires; /* + * When this transaction started, in nanoseconds [no locking] + */ + ktime_t t_start_time; + + /* * How many handles used this transaction? [t_handle_lock] */ int t_handle_count; @@ -939,8 +944,18 @@ struct journal_s struct buffer_head **j_wbuf; int j_wbufsize; + /* + * this is the pid of hte last person to run a synchronous operation + * through the journal + */ pid_t j_last_sync_writer; + /* + * the average amount of time in nanoseconds it takes to commit a + * transaction to disk. [j_state_lock] + */ + u64 j_average_commit_time; + /* This function is called when a transaction is closed */ void (*j_commit_callback)(journal_t *, transaction_t *); |
