• Goldwyn Rodrigues's avatar
    ocfs2: revert iput deferring code in ocfs2_drop_dentry_lock · 8ed6b237
    Goldwyn Rodrigues authored
    The following patches are reverted in this patch because these patches
    caused performance regression in the remote unlink() calls.
      ea455f8a - ocfs2: Push out dropping of dentry lock to ocfs2_wq
      f7b1aa69 - ocfs2: Fix deadlock on umount
      5fd13189 - ocfs2: Don't oops in ocfs2_kill_sb on a failed mount
    Previous patches in this series removed the possible deadlocks from
    downconvert thread so the above patches shouldn't be needed anymore.
    The regression is caused because these patches delay the iput() in case
    of dentry unlocks.  This also delays the unlocking of the open lockres.
    The open lockresource is required to test if the inode can be wiped from
    disk or not.  When the deleting node does not get the open lock, it
    marks it as orphan (even though it is not in use by another
    node/process) and causes a journal checkpoint.  This delays operations
    following the inode eviction.  This also moves the inode to the orphaned
    inode which further causes more I/O and a lot of unneccessary orphans.
    The following script can be used to generate the load causing issues:
      declare -a create
      declare -a remove
      declare -a iterations=(1 2 4 8 16 32 64 128 256 512 1024 2048 4096 8192 16384)
      unique="`mktemp -u XXXXX`"
      cat <<EOF > "${script}"
      for n in {1..8}; do mkdir -p test/dir\${n}
        eval touch test/dir\${n}/foo{1.."\$1"}
      chmod 700 "${script}"
      function fcreate ()
        exec 2>&1 /usr/bin/time --format=%E "${script}" "$1"
      function fremove ()
        exec 2>&1 /usr/bin/time --format=%E ssh node2 "cd `pwd`; rm -Rf test*"
      function fcp ()
        exec 2>&1 /usr/bin/time --format=%E ssh node3 "cd `pwd`; cp -R test test.new"
      echo -------------------------------------------------
      echo "| # files | create #s | copy #s | remove #s |"
      echo -------------------------------------------------
      for ((x=0; x < ${#iterations[*]} ; x++)) do
        create[$x]="`fcreate ${iterations[$x]}`"
        copy[$x]="`fcp ${iterations[$x]}`"
        printf "| %8d | %9s | %9s | %9s |\n" ${iterations[$x]} ${create[$x]} ${copy[$x]} ${remove[$x]}
      rm "${script}"
      echo "------------------------"
    Signed-off-by: default avatarSrinivas Eeda <srinivas.eeda@oracle.com>
    Signed-off-by: default avatarGoldwyn Rodrigues <rgoldwyn@suse.com>
    Signed-off-by: default avatarJan Kara <jack@suse.cz>
    Reviewed-by: default avatarMark Fasheh <mfasheh@suse.de>
    Cc: Joel Becker <jlbec@evilplan.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
dcache.c 12.9 KB