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    DateThu, 8 Apr 2004 11:50:43 +1000
    FromDavid Gibson <>
    SubjectRe: RFC: COW for hugepages
    On Wed, Apr 07, 2004 at 02:34:47PM +0200, Andi Kleen wrote:
    > On Wed, 7 Apr 2004 17:42:39 +1000
    > David Gibson <david@gibson.dropbear.id.au> wrote:
    > 
    > > Currently the kernel does not implement copy-on-write for huge pages -
    > > in fact any sort of page fault on a hugepage results in a SIGBUS.
    > > This means that hugepages *always* have MAP_SHARED semantics, even if
    > > MAP_PRIVATE is requested, and in particular that they are always
    > > shared across a fork().  Particularly when using hugetlbfs as just a
    > > source of quasi-anonymous memory, those are rather strange semantics.
    > 
    > [...]
    > 
    > Implementing this for ppc64 only is just wrong. Before you do this 
    > I would suggest to factor out the common code in the various hugetlbpage
    > implementations and then implement it in common code.
    
    Yes, I know it needs to be implemented for the other archs, but I
    wanted to get some feedback on the concept before diving into the
    other arch details to figure out how to implement it there.
    
    -- 
    David Gibson			| For every complex problem there is a
    david AT gibson.dropbear.id.au	| solution which is simple, neat and
    				| wrong.
    http://www.ozlabs.org/people/dgibson
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