Messages in this thread | | | Date | Fri, 11 Mar 2016 13:40:20 -0800 | Subject | Re: [PATCH 1/3] pfn_t: Change the encoding | From | Dan Williams <> |
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On Fri, Mar 11, 2016 at 1:13 PM, Matthew Wilcox <matthew.r.wilcox@intel.com> wrote: > By moving the flag bits to the bottom, we encourage commonality > between SGs with pages and those using pfn_t. We can also then insert > a pfn_t into a radix tree, as it uses the same two bits for indirect & > exceptional indicators.
It's not immediately clear to me what we gain with SG entry commonality. The down side is that we lose the property that pfn_to_pfn_t() is a nop. This was Dave's suggestion so that the nominal case did not change the binary layout of a typical pfn.
Can we just bit swizzle a pfn_t on insertion/retrieval from the radix?
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