arm64/sparsemem: reduce SECTION_SIZE_BITS
Status from this message: Applied to arm64 (for-next/misc), thanks!
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Patches in v1 Applied
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/1 | arm64/sparsemem: reduce SECTION_SIZE_BITSarch/ | +21 | 8 replies |
Reviews trailers per patch
The patch has a Reviewed-by or Acked-by.
| Patch | David Hildenbrand | Mike Rapoport | Catalin Marinas | Anshuman Khandual |
|---|---|---|---|---|
| 1/1 | R-b | A-b | R-b | R-b |
Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes. Scroll the table sideways for all 4 reviewers.
Cover letter [PATCH 0/1] arm64/sparsemem: reduce SECTION_SIZE_BITS
This patch is the follow-up from the discussions in the thread [1]. Reducing the section size has the merit of reducing wastage of reserved memory for vmmemmap mappings for sections with large memory holes. Also with smaller section size gives more grunularity and agility for memory hot(un)plugging.
But there are also constraints in reducing SECTION_SIZE_BIT:
- Should accommodate highest order page for a given config
- Should not break PMD mapping in vmemmap for 4K pages
- Should not consume too many page->flags bits reducing space for other info
This patch uses the suggestions from Anshuman Khandual and David Hildenbrand in thread [1] to set the least possible section size to 128MB for 4K and 16K base page size configs for simplicity, and to 512MB for 64K base page size config.
[1] https://lore.kernel.org/lkml/[email protected]/T/#m8ee60ae69db5e9eb06ca7999c43828d49ccb9626
Sudarshan Rajagopalan (1):
arm64/sparsemem: reduce SECTION_SIZE_BITS
arch/arm64/include/asm/sparsemem.h | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-)
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