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    SubjectRe: [patch 2/3] slub: scan partial list for free slabs when thrashing
    On Mon, 30 Mar 2009, Christoph Lameter wrote:

    > > Whenever a cpu cache satisfies a fastpath allocation, a fastpath counter
    > > is incrememted. This counter is cleared whenever the slowpath is
    > > invoked. This tracks how many fastpath allocations the cpu slab has
    > > fulfilled before it must be refilled.
    >
    > That adds fastpath overhead and it shows for small objects in your tests.
    >

    Indeed, which is unavoidable in this case. The only other way of tracking
    the "thrashing history" I can think of would be bitshifting a 1 for
    slowpath and 0 for fastpath, for example, into an unsigned long. That,
    however, requires a hamming weight calculation in the slowpath and doesn't
    scale nearly as well as simply an incrementing a counter.

    If there's other approaches on tracking such instances, I'd be interested
    to hear them.

    Btw, is cl@linux.com your new email address or are all
    linux-foundation.org emails going to eventually migrate to the new domain?


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