The two hottest locks, and thus the biggest scalability bottlenecks, in the jbd2 layer, are the j_list_lock and j_state_lock. This has inspired some people to do some truly unnatural things[1]. [1] https://www.usenix.org/system/files/conference/fast14/fast14-paper_kang.pdf We don't need to be holding both j_state_lock and j_list_lock while calculating the journal statistics, so move those calculations to the very end of jbd2_journal_commit_transaction. Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx> --- fs/jbd2/commit.c | 36 ++++++++++++++++++------------------ 1 file changed, 18 insertions(+), 18 deletions(-) diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 765b31d..af36252 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -1083,24 +1083,7 @@ restart_loop: atomic_read(&commit_transaction->t_handle_count); trace_jbd2_run_stats(journal->j_fs_dev->bd_dev, commit_transaction->t_tid, &stats.run); - - /* - * Calculate overall stats - */ - spin_lock(&journal->j_history_lock); - journal->j_stats.ts_tid++; - if (commit_transaction->t_requested) - journal->j_stats.ts_requested++; - journal->j_stats.run.rs_wait += stats.run.rs_wait; - journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay; - journal->j_stats.run.rs_running += stats.run.rs_running; - journal->j_stats.run.rs_locked += stats.run.rs_locked; - journal->j_stats.run.rs_flushing += stats.run.rs_flushing; - journal->j_stats.run.rs_logging += stats.run.rs_logging; - journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count; - journal->j_stats.run.rs_blocks += stats.run.rs_blocks; - journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged; - spin_unlock(&journal->j_history_lock); + stats.ts_requested = (commit_transaction->t_requested) ? 1 : 0; commit_transaction->t_state = T_COMMIT_CALLBACK; J_ASSERT(commit_transaction == journal->j_committing_transaction); @@ -1157,4 +1140,21 @@ restart_loop: spin_unlock(&journal->j_list_lock); write_unlock(&journal->j_state_lock); wake_up(&journal->j_wait_done_commit); + + /* + * Calculate overall stats + */ + spin_lock(&journal->j_history_lock); + journal->j_stats.ts_tid++; + journal->j_stats.ts_requested += stats.ts_requested; + journal->j_stats.run.rs_wait += stats.run.rs_wait; + journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay; + journal->j_stats.run.rs_running += stats.run.rs_running; + journal->j_stats.run.rs_locked += stats.run.rs_locked; + journal->j_stats.run.rs_flushing += stats.run.rs_flushing; + journal->j_stats.run.rs_logging += stats.run.rs_logging; + journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count; + journal->j_stats.run.rs_blocks += stats.run.rs_blocks; + journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged; + spin_unlock(&journal->j_history_lock); } -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
