On 22/09/07 07:59PM, Alexey Lyashkov wrote: > From: Andrew Perepechko <anserper@xxxxx> > > LIFO wakeup order is unfair and sometimes leads to a journal > user not being able to get a journal handle for hundreds of > transactions in a row. > > FIFO wakeup can make things more fair. prepare_to_wait() will always add the task to the head of the list. While prepare_to_wait_exclusive() will add the task to the tail since all of the exclusive tasks are added to the tail. wake_up() function will wake up all non-exclusive and single exclusive task v/s wake_up_all() function will wake up all tasks irrespective. So your change does makes the ordering to FIFO, in which the task which came in first will be woken up first. Although I was wondering about 2 things - 1. In what scenario this was observed to become a problem/bottleneck for you? Could you kindly give more details of your problem? 2. What about start_this_handle() function where we call wait_event() for j_barrier_count to be 0? I guess that doesn't happen often. -ritesh > > Signed-off-by: Alexey Lyashkov <alexey.lyashkov@xxxxxxxxx> > --- > fs/jbd2/commit.c | 2 +- > fs/jbd2/transaction.c | 6 +++--- > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c > index b2b2bc9b88d9..ec2b55879e3a 100644 > --- a/fs/jbd2/commit.c > +++ b/fs/jbd2/commit.c > @@ -570,7 +570,7 @@ void jbd2_journal_commit_transaction(journal_t *journal) > journal->j_running_transaction = NULL; > start_time = ktime_get(); > commit_transaction->t_log_start = journal->j_head; > - wake_up(&journal->j_wait_transaction_locked); > + wake_up_all(&journal->j_wait_transaction_locked); > write_unlock(&journal->j_state_lock); > > jbd2_debug(3, "JBD2: commit phase 2a\n"); > diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c > index e1be93ccd81c..6a404ac1c178 100644 > --- a/fs/jbd2/transaction.c > +++ b/fs/jbd2/transaction.c > @@ -168,7 +168,7 @@ static void wait_transaction_locked(journal_t *journal) > int need_to_start; > tid_t tid = journal->j_running_transaction->t_tid; > > - prepare_to_wait(&journal->j_wait_transaction_locked, &wait, > + prepare_to_wait_exclusive(&journal->j_wait_transaction_locked, &wait, > TASK_UNINTERRUPTIBLE); > need_to_start = !tid_geq(journal->j_commit_request, tid); > read_unlock(&journal->j_state_lock); > @@ -194,7 +194,7 @@ static void wait_transaction_switching(journal_t *journal) > read_unlock(&journal->j_state_lock); > return; > } > - prepare_to_wait(&journal->j_wait_transaction_locked, &wait, > + prepare_to_wait_exclusive(&journal->j_wait_transaction_locked, &wait, > TASK_UNINTERRUPTIBLE); > read_unlock(&journal->j_state_lock); > /* > @@ -920,7 +920,7 @@ void jbd2_journal_unlock_updates (journal_t *journal) > write_lock(&journal->j_state_lock); > --journal->j_barrier_count; > write_unlock(&journal->j_state_lock); > - wake_up(&journal->j_wait_transaction_locked); > + wake_up_all(&journal->j_wait_transaction_locked); > } > > static void warn_dirty_buffer(struct buffer_head *bh) > -- > 2.31.1 >
