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Message-Id: <1359654788-6078-1-git-send-email-tytso@mit.edu> Date: Thu, 31 Jan 2013 12:53:05 -0500 From: Theodore Ts'o <tytso@....edu> To: Ext4 Developers List <linux-ext4@...r.kernel.org> Cc: Theodore Ts'o <tytso@....edu> Subject: [PATCH 0/3 v2] jbd2 performance improvements I've added a patch which tracks the delay between when a commit was first requested, and when the commit thread actually starts processing the commit. In addition to helping to assess the effects of the "commit as soon as possible after log_start_commit", it is also useful in debugging problems caused by real time processes which might interfere with the kjournald thread (since we've had one user ask a question about this already). There are other performance metrics that we should consider adding, including: *) using a per-cpu variable to track t_max_wait, so we can measure this performance metric without incurring a scalability penalty; we currently disable this unless debugging is enabled, which is unfortunate. *) how many handles are getting blocked waiting for a transaction to finish, and not just the max wait time *) keeping statistics of why various commits have been started (was it due to an explicit fsync, or due to O_SYNC, or due to the transaction time expiring --- and in the latter case, whether it is due to an expiry while the file system was idle, and hence was picked up by kjournald, or during the stop_this_handle processing) But these are things we can save for another time... - Ted Eric Sandeen (1): jbd2: don't wake kjournald unnecessarily Theodore Ts'o (2): jbd2: commit as soon as possible after log_start_commit jbd2: track request delay statistics fs/jbd2/commit.c | 13 ++++++++++++- fs/jbd2/journal.c | 17 ++++++++++++++--- fs/jbd2/transaction.c | 7 +++++-- include/linux/jbd2.h | 8 ++++++++ include/trace/events/jbd2.h | 8 ++++++-- 5 files changed, 45 insertions(+), 8 deletions(-) -- 1.7.12.rc0.22.gcdd159b -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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