On 8/27/24 1:08 AM, Shin'ichiro Kawasaki wrote: > When write_lat_log option is set, fio outputs the 'clat' completion > latency log file. This clat log can be used to analyze IO latency. This > file can also be considered as an IO trace file as each IO entry can > fully describe an IO when the --log_offset and --log_prio options are > also used. However, using the clat log file as an IO trace is inaccurate > because the time field of each entry uses millisecond units, which is > too coarse for fast IOs (e.g. when using SSDs). This series proposes the > new option 'log_issue_time' to address the inaccuracy problem. When this > option is set, fio adds another field to the log file entries to log an > IO issuing time in nanoseconds. > > The first four patches in the series clean up the current code as > preparation. The 5th patch introduces the 'log_issue_time' option. The > following two patches document the new option. The last two patches add > two test cases to check the log file format. In general this looks fine, and I think it's a useful feature. However, should we have an option to make the generic time in the log entry be in nsec as well? -- Jens Axboe
