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    SubjectRe: [PATCH 24/25] r/o bind mounts: track number of mount writers
    On Mon, Sep 24, 2007 at 12:10:35PM -0700, Andrew Morton wrote:
    > > As we already say in various messages the percpu counters in here
    > > look rather fishy. I'd recomment to take a look at the per-cpu
    > > superblock counters in XFS as they've been debugged quite well
    > > now and could probably be lifted into a generic library for this
    > > kind of think. The code is mostly in fs/xfs/xfs_mount.c can
    > > can be spotted by beeing under #ifdef HAVE_PERCPU_SB.
    > >
    > > It also handles cases like hotplug cpu nicely that this code
    > > seems to work around by always iterating over all possible cpus
    > > which might not be nice on a dual core laptop with a distro kernel
    > > that also has to support big iron.
    > hm. How come xfs invented a new version of percpu_counters?

    This code actually predates the generic percpu_counters even if it
    was merged to mainline later. Neither Dave who wrote it nor me
    who reviewed it before it was merged thought of percpu_counters
    probably. Then again this code is considerably more complex due
    to features actually needed in a very hot fastpath.
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      Last update: 2007-09-24 21:53    [W:0.019 / U:0.876 seconds]
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