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  1. Lustre
  2. LU-487

procfs stats file incorrectly records brw_read and brw_write values

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: Lustre 2.1.0, Lustre 1.8.6
    • Fix Version/s: Lustre 2.1.0
    • Labels:
      None
    • Severity:
      3
    • Epic:
    • Rank (Obsolete):
      4929

      Description

      brw_read in llite client procfs stats file claims to measure in units of pages. For example:

      # cat /proc/fs/lustre/llite/lustre-ffff88000449a800/stats
      snapshot_time             1308264214.464257 secs.usecs
      dirty_pages_hits          1419716 samples [regs]
      dirty_pages_misses        833472 samples [regs]
      read_bytes                322963 samples [bytes] 1 2684356 154236888794
      write_bytes               225001 samples [bytes] 0 125912 3323679002
      brw_read                  15285 samples [pages] 4096 4096 62607360
      

      However, in ./lustre/llite/lloop.c the tallying of the LPROC_LL_BRW_WRITE/READ counter increments by the value of:

      page_count << PAGE_CACHE_SHIFT
      

      Using this value has the effect of not measure pages, but the total bytes of the pages. A simple fix maybe to remove the PAGE_CACHE_SHIFT. Or, rename '[pages]' to '[bytes]' in the output.

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              • Assignee:
                rhenwood Richard Henwood (Inactive)
                Reporter:
                rhenwood Richard Henwood (Inactive)
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                • Created:
                  Updated:
                  Resolved: