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  1. Lustre
  2. LU-9161

mount_utils_ldiskfs.c is_feature_enabled() should pass '-c' to debugfs

Details

    • Bug
    • Resolution: Fixed
    • Minor
    • Lustre 2.10.0
    • None
    • 3
    • 9223372036854775807

    Description

      The meta_bg feature unfortunately fragments the group descriptor block across the whole filesystem, rather than continuously at the start of the device. This causes a large amount of seeking (at least 32768 seeks for a 256TB filesystem).

      Skipping the loading of inode tables and bitmaps via -c will avoid reading many GB of data.

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            [LU-9161] mount_utils_ldiskfs.c is_feature_enabled() should pass '-c' to debugfs
            pjones Peter Jones added a comment -

            Landed for 2.10

            pjones Peter Jones added a comment - Landed for 2.10

            Oleg Drokin (oleg.drokin@intel.com) merged in patch https://review.whamcloud.com/25671/
            Subject: LU-9161 utils: don't load bitmaps when checking features
            Project: fs/lustre-release
            Branch: master
            Current Patch Set:
            Commit: 153c25f280d3db722005619ea0db6fbd3d26bc97

            gerrit Gerrit Updater added a comment - Oleg Drokin (oleg.drokin@intel.com) merged in patch https://review.whamcloud.com/25671/ Subject: LU-9161 utils: don't load bitmaps when checking features Project: fs/lustre-release Branch: master Current Patch Set: Commit: 153c25f280d3db722005619ea0db6fbd3d26bc97

            Andreas Dilger (andreas.dilger@intel.com) uploaded a new patch: https://review.whamcloud.com/25671
            Subject: LU-9161 utils: don't load bitmaps when checking features
            Project: fs/lustre-release
            Branch: master
            Current Patch Set: 1
            Commit: e9d8b14e3f893b1e82561b47c84b2000e7e2c2c3

            gerrit Gerrit Updater added a comment - Andreas Dilger (andreas.dilger@intel.com) uploaded a new patch: https://review.whamcloud.com/25671 Subject: LU-9161 utils: don't load bitmaps when checking features Project: fs/lustre-release Branch: master Current Patch Set: 1 Commit: e9d8b14e3f893b1e82561b47c84b2000e7e2c2c3

            Instead of running debugfs in a shell and parsing the text output, we might consider just reading struct ext4_super_block at offset 1024 bytes, and then checking the binary feature flags directly. That will avoid all overhead from reading the group descriptors and any other metadata. Another alternative is to modify debugfs to avoid loading the bitmaps until required (possibly only starting a background prefetch at filesystem open time) as an extension of the LU-9160 patch.

            adilger Andreas Dilger added a comment - Instead of running debugfs in a shell and parsing the text output, we might consider just reading struct ext4_super_block at offset 1024 bytes, and then checking the binary feature flags directly. That will avoid all overhead from reading the group descriptors and any other metadata. Another alternative is to modify debugfs to avoid loading the bitmaps until required (possibly only starting a background prefetch at filesystem open time) as an extension of the LU-9160 patch.

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              wc-triage WC Triage
              jhammond John Hammond
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              Dates

                Created:
                Updated:
                Resolved: