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    SubjectRe: Purpose of the mm/slab.c changes
    On Sun, Sep 09, 2001 at 01:58:44PM -0700, Davide Libenzi wrote:

    > >> Do You see it as a plus ?
    > >> The new allocated slab will be very likely written ( w/o regard
    > >> about the old content ) and an L2 mapping will generate
    > >> invalidate traffic.
    > >
    > > If your invalidates are slower than your RAM, you should
    > > consider getting another computer.
    >
    > You mean a Sun, that uses a separate bus for snooping ? :)
    > Besides to not under estimate the cache coherency traffic ( that on many CPUs
    > uses the main memory bus ) there's the fact that the old data eventually
    > present in L2 won't be used by the new slab user.

    That's actually what having a slab cache of pre-initialized elements tries
    to achieve.

    On anything that uses a MESI-like cache coherence protocol a cached dirty
    cache line that is written to will not cause any coherency traffic and
    thus be faster.

    Ralf

    --
    "Embrace, Enhance, Eliminate" - it worked for the pope, it'll work for Bill.
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