PATCH: new GC implementation

[Mark Mitchell]

>>>>> "Andi" == Andi Kleen <ak@muc.de> writes:

    Andi> Yes there is actually. Sorry I was wrong. MAP_ANONYMOUS does
    Andi> not manipulate the the page tables directly, but only
    Andi> creates a vma (a highlevel memory object) for the mapped
    Andi> range. The actual pte is only updated on access.  /dev/zero
    Andi> directly sets up all the ptes, which can be a quite slow
    Andi> operation on x86 especially on SMP (the CPU always flushes
    Andi> page table changes to the memory bus).

    Andi> This is actually a bug, it should really use the same method
    Andi> as MAP_ANONYMOUS.  Thank you for finding it.

Thanks for the explanation.  I think that means we should leave the
use of MAP_ANONYMOUS in the new GC (in contrast to what RTH suggested
in his mail to Alex); lots of us are going to be running our current
kernels for quite some time.

--
Mark Mitchell                   mark@codesourcery.com
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