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jbd2: Improve scalability by not taking j_state_lock in jbd2_journal_stop()

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One of the most contended locks in the jbd2 layer is j_state_lock when
running dbench.  This is especially true if using the real-time kernel
with its "sleeping spinlocks" patch that replaces spinlocks with
priority inheriting mutexes --- but it also shows up on large SMP
benchmarks.

Thanks to John Stultz for pointing this out.

Reviewed by Mingming Cao and Jan Kara.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2010-05-16 05:00:00 -04:00
parent c445e3e0a5
commit c35a56a090
1 changed files with 1 additions and 4 deletions
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5
fs/jbd2/transaction.c
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@ -1311,7 +1311,6 @@ int jbd2_journal_stop(handle_t *handle)
if (handle->h_sync)
transaction->t_synchronous_commit = 1;
current->journal_info = NULL;
spin_lock(&journal->j_state_lock);
spin_lock(&transaction->t_handle_lock);
transaction->t_outstanding_credits -= handle->h_buffer_credits;
transaction->t_updates--;
@ -1340,8 +1339,7 @@ int jbd2_journal_stop(handle_t *handle)
jbd_debug(2, "transaction too old, requesting commit for "
"handle %p\n", handle);
/* This is non-blocking */
__jbd2_log_start_commit(journal, transaction->t_tid);
spin_unlock(&journal->j_state_lock);
jbd2_log_start_commit(journal, transaction->t_tid);
/*
* Special case: JBD2_SYNC synchronous updates require us
@ -1351,7 +1349,6 @@ int jbd2_journal_stop(handle_t *handle)
err = jbd2_log_wait_commit(journal, tid);
} else {
spin_unlock(&transaction->t_handle_lock);
spin_unlock(&journal->j_state_lock);
}
lock_map_release(&handle->h_lockdep_map);