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B.8. Log tracepoints
The tracepoints in this subsystem track blocks being added to and removed from the journal (
gfs2_pin), as well as the time taken to commit the transactions to the log (
gfs2_log_flush). This can be very useful when trying to debug journaling performance issues.
gfs2_log_blockstracepoint keeps track of the reserved blocks in the log, which can help show if the log is too small for the workload, for example.
gfs2_ail_flushtracepoint is similar to the
gfs2_log_flushtracepoint in that it keeps track of the start and end of flushes of the AIL list. The AIL list contains buffers which have been through the log, but have not yet been written back in place and this is periodically flushed in order to release more log space for use by the file system, or when a process requests a