0889eba5b3
x86_64 uses 2M page table entries to map its 1-1 kernel space. We also implement the virtual memmap using 2M page table entries. So there is no additional runtime overhead over FLATMEM, initialisation is slightly more complex. As FLATMEM still references memory to obtain the mem_map pointer and SPARSEMEM_VMEMMAP uses a compile time constant, SPARSEMEM_VMEMMAP should be superior. With this SPARSEMEM becomes the most efficient way of handling virt_to_page, pfn_to_page and friends for UP, SMP and NUMA on x86_64. [apw@shadowen.org: code resplit, style fixups] [apw@shadowen.org: vmemmap x86_64: ensure end of section memmap is initialised] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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