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Date:   Thu, 30 Aug 2018 17:55:03 -0400
From:   Waiman Long <>
To:     Alexander Viro <>,
        Jonathan Corbet <>
        "Luis R. Rodriguez" <>,
        Kees Cook <>,
        Linus Torvalds <>,
        Jan Kara <>,
        "Paul E. McKenney" <>,
        Andrew Morton <>,
        Ingo Molnar <>,
        Miklos Szeredi <>,
        Matthew Wilcox <>,
        Larry Woodman <>,
        James Bottomley <>,
        "Wangkai (Kevin C)" <>,
        Michal Hocko <>,
        Waiman Long <>
Subject: [PATCH v2 0/4] fs/dcache: Track # of negative dentries

  - Clarify what the new nr_dentry_negative per-cpu counter is tracking
    and open-code the increment and decrement as suggested by Dave Chinner.
  - Append the new nr_dentry_negative count as the 7th element of dentry-state
    instead of replacing one of the dummy entries.
  - Remove patch "fs/dcache: Make negative dentries easier to be
    reclaimed" for now as I need more time to think about what
    to do with it.
  - Add 2 more patches to address issues found while reviewing the
    dentry code.
  - Add another patch to change the conditional branch of
    nr_dentry_negative accounting to conditional move so as to reduce
    the performance impact of the accounting code.

This patchset addresses 2 issues found in the dentry code and adds a
new nr_dentry_negative per-cpu counter to track the total number of
negative dentries in all the LRU lists.

Patch 1 fixes a bug in the accounting of nr_dentry_unused in

Patch 2 removes the ____cacheline_aligned_in_smp tag from super_block
LRU lists.

Patch 3 adds the new nr_dentry_negative per-cpu counter.

Patch 4 removes conditional branches in nr_dentry_negative accounting

Various filesystem related tests were run and no statistically
significant changes in performance was observed.

Waiman Long (4):
  fs/dcache: Fix incorrect nr_dentry_unused accounting in
  fs: Don't need to put list_lru into its own cacheline
  fs/dcache: Track & report number of negative dentries
  fs/dcache: Eliminate branches in nr_dentry_negative accounting

 Documentation/sysctl/fs.txt | 22 +++++++++++-------
 fs/dcache.c                 | 54 ++++++++++++++++++++++++++++++++++++++++-----
 include/linux/dcache.h      |  5 +++--
 include/linux/fs.h          |  9 ++++----
 kernel/sysctl.c             |  2 +-
 5 files changed, 72 insertions(+), 20 deletions(-)


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