From: Theodore Ts'o <tytso@mit.edu>
To: Roy Yang <bsdnet@outlook.com>
Cc: "linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: fsync stuck at jbd2_log_wait_commit on NVMe devices
Date: Wed, 12 Aug 2015 14:37:50 -0400 [thread overview]
Message-ID: <20150812183750.GB3373@thunk.org> (raw)
In-Reply-To: <COL130-W652BF73D365EBB4F3DDF69D67E0@phx.gbl>
Hi Roy,
My suggestion is to collect information from the jbd2_run_stats and
jbd2_checkpoint_stats tracepoints.
cd /sys/kernel/debug/tracing
echo 1 > events/jbd2/jbd2_run_stats/enable
echo 1 > events/jbd2/jbd2_checkpoint_stats/enable
cat trace_pipe > /tmp/traces &
tail -f /tmp/traces
The jbd2_handle_stats tracepoint can be informative, but it's also far
more voluminous.
That will give us a hint where things are getting bottlenecked.
What sort of workload is your application doing? Is it just primarily
doing random writes into a preallocated file? Is it creating or
deleting files? Extending or truncating files? etc.
- Ted
next prev parent reply other threads:[~2015-08-12 18:37 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-12 16:57 fsync stuck at jbd2_log_wait_commit on NVMe devices Roy Yang
2015-08-12 18:37 ` Theodore Ts'o [this message]
2015-08-12 19:28 ` Roy Yang
2015-08-12 21:43 ` Roy Yang
2015-08-12 22:34 ` Theodore Ts'o
2015-08-12 23:34 ` Roy Yang
2015-08-13 13:09 ` Theodore Ts'o
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