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* [PATCH 0/1] arm64: make section size configurable for memory hotplug
@ 2021-01-06  1:28 Sudarshan Rajagopalan
  2021-01-06  1:28 ` [PATCH 1/1] " Sudarshan Rajagopalan
  0 siblings, 1 reply; 11+ messages in thread
From: Sudarshan Rajagopalan @ 2021-01-06  1:28 UTC (permalink / raw)
  To: akpm, linux-mm, linux-kernel; +Cc: Sudarshan Rajagopalan

The section size defines the granularity of memory hotplug. This is currently
hard coded to 1GB on arm64 linux, which defines that the least size of memblock
that can be hotplugged out is 1GB. Some DDR configurations (especially low RAM
and dual-rank DDRs) may have section sizes that are less than 1GB (ex. 512MB, 256MB etc.).
Having an option to reduce the memblock size to section size or lower gives more
granularity of memory hotplug. For example, a system with DDR section size of 512MB
and kernel memblock size of 1GB, we would have to remove two segments of DDR sections
in order to hotplug out atleast 1 memblock from kernel POV. 

Section sizes of DDRs vary based on specs (number of ranks, channels, regions etc.)
Making this section size configurable helps users to assign based on the DDR being used.
The default is set to 1GB which is the current memblock size.

Sudarshan Rajagopalan (1):
  arm64: Make section size configurable for memory hotplug

 arch/arm64/Kconfig                 | 11 +++++++++++
 arch/arm64/include/asm/sparsemem.h |  4 ++++
 2 files changed, 15 insertions(+)

Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

^ permalink raw reply	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2021-01-11 10:26 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-01-06  1:28 [PATCH 0/1] arm64: make section size configurable for memory hotplug Sudarshan Rajagopalan
2021-01-06  1:28 ` [PATCH 1/1] " Sudarshan Rajagopalan
2021-01-06  2:20   ` Randy Dunlap
2021-01-06  6:11   ` Anshuman Khandual
2021-01-07 12:30     ` David Hildenbrand
2021-01-08  7:02       ` Anshuman Khandual
2021-01-08 15:30         ` David Hildenbrand
2021-01-11  4:17           ` Anshuman Khandual
2021-01-11 10:13             ` David Hildenbrand
2021-01-11 10:26               ` Anshuman Khandual
2021-01-08  1:01     ` Sudarshan Rajagopalan

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