Messages in this thread | | | Date | Fri, 16 Mar 2007 13:52:18 -0700 (PDT) | From | Christoph Lameter <> | Subject | Re: [PATCH 00/18] Make common x86 arch area for i386 and x86_64 - Take 2 |
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On Fri, 16 Mar 2007, David Miller wrote:
> > It is primarily a performance improvement since the sparsemem table > > lookups would no longer be necessary and it also streamlines other > > frequent cacheline uses. These page -> page_struct and vice versa > > operations are key to the performance of various subsystem among them > > the slab allocator. > > If you set the bit range small enough and don't use sparsemem-extreme, > the cost is extremely low considering the flexibility you obtain.
What flexibility?
> There are always going to be holes on large systems, there isn't > really a way to avoid this given how addressing is done on those > machines.
Virtual mmap allows holes in the same way as page tables do. These structures were designed for sparseness. I really do not think we should rediscuss the material here that was discussed on linux-mm. The outcome of that was that we will introduce virtual memmap to reduce sparsemem overhead and to increase flexibility.
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