Messages in this thread | | | Date | Wed, 08 Oct 2008 11:17:59 -0500 | From | Christoph Lameter <> | Subject | Re: [PATCH 1/1] hugetlbfs: handle pages higher order than MAX_ORDER |
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Andy Whitcroft wrote: > When working with hugepages, hugetlbfs assumes that those hugepages > are smaller than MAX_ORDER. Specifically it assumes that the mem_map > is contigious and uses that to optimise access to the elements of the > mem_map that represent the hugepage. Gigantic pages (such as 16GB pages > on powerpc) by definition are of greater order than MAX_ORDER (larger > than MAX_ORDER_NR_PAGES in size). This means that we can no longer make > use of the buddy alloctor guarentees for the contiguity of the mem_map, > which ensures that the mem_map is at least contigious for maximmally > aligned areas of MAX_ORDER_NR_PAGES pages.
But the memmap is contiguous in most cases. FLATMEM, VMEMMAP etc. Its only some special sparsemem configurations that couldhave the issue because they break up the vmemmap. x86_64 uses VMEMMAP by default. Is this for i386?
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