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    SubjectRe: userspace pagecache management tool
    On Sat, 3 Mar 2007 20:16:09 -0500 "Lee Revell" <rlrevell@joe-job.com> wrote:

    > On 3/3/07, Andrew Morton <akpm@linux-foundation.org> wrote:
    > > The tool uses an LD_PRELOAD hack to intercept glibc's read(), pread(),
    > > write(), pwrite(), close() and dup2() functions. pagecache control is done
    > > via posix_fadvise() and sync_file_range().
    > >
    >
    > How could this have any effect on the updatedb problem? updatedb does
    > not read() anything, it just open()s and stat()s every file on the
    > disk.
    >

    err, good point. _one_ of those dang things which goes off when you've
    stayed up too late does a lot of pagecache IO, not sure which one. Maybe
    rpmq? But I'd expect that to be doing direct-io.

    But yes, updatedb's pagecache usage will be mainly metadata, and this tool
    doesn't address metadata pagecache, although it could do so.

    <does an updatedb on a modest system>

    It instantiated 5MB of pagecache and 20MB of slab, took about one minute.

    <runs all the other things in /etc/cron.daily>

    rpm uses rather a lot of pagecache.

    So yes, it looks like updatedb is a slab problem.
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