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    SubjectRe: [PATCH 20/20] Get rid of the concept of hot/cold page freeing
    On Tue, 24 Feb 2009 11:51:26 +0000
    Mel Gorman <mel@csn.ul.ie> wrote:

    > > > Almost the opposite with steady improvements almost all the way through.
    > > >
    > > > With the patch applied, we are still using hot/cold information on the
    > > > allocation side so I'm somewhat surprised the patch even makes much of a
    > > > difference. I'd have expected the pages being freed to be mostly hot.
    > >
    > > Oh yeah. Back in the ancient days, hot-cold-pages was using separate
    > > magazines for hot and cold pages. Then Christoph went and mucked with
    > > it, using a single queue. That might have affected things.
    > >
    >
    > It might have. The impact is that requests for cold pages can get hot pages
    > if there are not enough cold pages in the queue so readahead could prevent
    > an active process getting cache hot pages. I don't think that would have
    > showed up in the microbenchmark though.

    We switched to doing non-temporal stores in copy_from_user(), didn't
    we? That would rub out the benefit which that microbenchmark
    demonstrated?



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