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  1. Lustre
  2. LU-17853

Negative value reported in req_waittime mdt

Details

    • Bug
    • Resolution: Fixed
    • Minor
    • Lustre 2.16.0
    • Lustre 2.14.0
    • 3
    • 9223372036854775807

    Description

      ldlm.services.ldlm_canceld.stats=
snapshot_time             1714662722.986857642 secs.nsecs
req_waittime              101358239600 samples [usecs] -36 1855805 5530720965329 21563670935443407
req_qdepth                101358239600 samples [reqs] 0 1164 1893537183 7828947261
req_active                101358239600 samples [reqs] 1 23 152657095033 281200017837
req_timeout               101358239600 samples [secs] 1 218 6892805470378 468801155450006
reqbuf_avail              210996467581 samples [bufs] 0 155 13398749465845 850967459690601
ldlm_cancel               101358239600 samples [usecs] 1 211241571 1436530054018 108103493490971286

      This doesn't appear to be a math error like LU-9683, but possibly caused by NTP.

      ptlrpc uses ktime_get_real() for timing events where other modules use ktime_get() for timing.

      ktime_get_real() "can jump backwards due to a leap second update, NTP adjustment settimeofday() operation from user space."

      Attachments

        Issue Links

          is related to

          Bug - A problem which impairs or prevents the functions of the product. LU-9683 Negative value reported for req_waittime mdt stat

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Activity

            [LU-17853] Negative value reported in req_waittime mdt
            pjones Peter Jones made changes -
            Fix Version/s New: Lustre 2.16.0 [ 15190 ]
            Resolution New: Fixed [ 1 ]
            Status Original: Open [ 1 ] New: Resolved [ 5 ]
            adilger Andreas Dilger made changes -
            Assignee Original: WC Triage [ wc-triage ] New: Fred Dilger [ fdilger ]
            adilger Andreas Dilger made changes -
            Labels New: easy
            adilger Andreas Dilger made changes -
            Summary Original: Netagive value reported in req_waittime mdt New: Negative value reported in req_waittime mdt
            utopiabound Nathaniel Clark made changes -
            Summary Original: Netagive value reported in req_wait mdt New: Netagive value reported in req_waittime mdt
            utopiabound Nathaniel Clark made changes -
            Link New: This issue is related to DDN-4992 [ DDN-4992 ]
            utopiabound Nathaniel Clark made changes -
            Link New: This issue is related to LU-9683 [ LU-9683 ]
            utopiabound Nathaniel Clark created issue -

            People

              fdilger Fred Dilger
              utopiabound Nathaniel Clark
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              Dates

                Created:
                Updated:
                Resolved: