On Wed, Jun 05, 2019 at 02:57:59PM -0700, Dan Williams wrote:
> Prepare for hot{plug,remove} of sub-ranges of a section by tracking a
> sub-section active bitmask, each bit representing a PMD_SIZE span of the
> architecture's memory hotplug section size.
>
> The implications of a partially populated section is that pfn_valid()
> needs to go beyond a valid_section() check and read the sub-section
> active ranges from the bitmask. The expectation is that the bitmask
> (subsection_map) fits in the same cacheline as the valid_section() data,
> so the incremental performance overhead to pfn_valid() should be
> negligible.
>
> Cc: Michal Hocko <[email protected]>
> Cc: Vlastimil Babka <[email protected]>
> Cc: Logan Gunthorpe <[email protected]>
> Cc: Oscar Salvador <[email protected]>
> Cc: Pavel Tatashin <[email protected]>
> Tested-by: Jane Chu <[email protected]>
> Signed-off-by: Dan Williams <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
--
Oscar Salvador
SUSE L3
