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authorLinus Torvalds <torvalds@linux-foundation.org>2023-04-24 12:35:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2023-04-24 12:35:49 -0700
commitc23f28975abc2eb02cecc8bc1f2c95473a59ed2e (patch)
treed356762219c0d3079d37f1cc3ab3eef5cd37567a /Documentation/mm
parent1be89faab3cf1f3dd6eb4924b60d2b9094e7206b (diff)
parent7e8472c820f04517ae5d5a27c1aecfa2263a0aa5 (diff)
downloadlinux-c23f28975abc2eb02cecc8bc1f2c95473a59ed2e.tar.gz
Merge tag 'docs-6.4' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet: "Commit volume in documentation is relatively low this time, but there is still a fair amount going on, including: - Reorganize the architecture-specific documentation under Documentation/arch This makes the structure match the source directory and helps to clean up the mess that is the top-level Documentation directory a bit. This work creates the new directory and moves x86 and most of the less-active architectures there. The current plan is to move the rest of the architectures in 6.5, with the patches going through the appropriate subsystem trees. - Some more Spanish translations and maintenance of the Italian translation - A new "Kernel contribution maturity model" document from Ted - A new tutorial on quickly building a trimmed kernel from Thorsten Plus the usual set of updates and fixes" * tag 'docs-6.4' of git://git.lwn.net/linux: (47 commits) media: Adjust column width for pdfdocs media: Fix building pdfdocs docs: clk: add documentation to log which clocks have been disabled docs: trace: Fix typo in ftrace.rst Documentation/process: always CC responsible lists docs: kmemleak: adjust to config renaming ELF: document some de-facto PT_* ABI quirks Documentation: arm: remove stih415/stih416 related entries docs: turn off "smart quotes" in the HTML build Documentation: firmware: Clarify firmware path usage docs/mm: Physical Memory: Fix grammar Documentation: Add document for false sharing dma-api-howto: typo fix docs: move m68k architecture documentation under Documentation/arch/ docs: move parisc documentation under Documentation/arch/ docs: move ia64 architecture docs under Documentation/arch/ docs: Move arc architecture docs under Documentation/arch/ docs: move nios2 documentation under Documentation/arch/ docs: move openrisc documentation under Documentation/arch/ docs: move superh documentation under Documentation/arch/ ...
Diffstat (limited to 'Documentation/mm')
-rw-r--r--Documentation/mm/physical_memory.rst21
1 files changed, 20 insertions, 1 deletions
diff --git a/Documentation/mm/physical_memory.rst b/Documentation/mm/physical_memory.rst
index 1bc888d36ea13..531e73b003ddd 100644
--- a/Documentation/mm/physical_memory.rst
+++ b/Documentation/mm/physical_memory.rst
@@ -19,7 +19,7 @@ a bank of memory very suitable for DMA near peripheral devices.
Each bank is called a node and the concept is represented under Linux by a
``struct pglist_data`` even if the architecture is UMA. This structure is
-always referenced to by it's typedef ``pg_data_t``. ``A pg_data_t`` structure
+always referenced by its typedef ``pg_data_t``. A ``pg_data_t`` structure
for a particular node can be referenced by ``NODE_DATA(nid)`` macro where
``nid`` is the ID of that node.
@@ -114,6 +114,25 @@ RAM equally split between two nodes, there will be ``ZONE_DMA32``,
| DMA32 | NORMAL | MOVABLE | | NORMAL | MOVABLE |
+---------+----------+-----------+ +------------+-------------+
+
+Memory banks may belong to interleaving nodes. In the example below an x86
+machine has 16 Gbytes of RAM in 4 memory banks, even banks belong to node 0
+and odd banks belong to node 1::
+
+
+ 0 4G 8G 12G 16G
+ +-------------+ +-------------+ +-------------+ +-------------+
+ | node 0 | | node 1 | | node 0 | | node 1 |
+ +-------------+ +-------------+ +-------------+ +-------------+
+
+ 0 16M 4G
+ +-----+-------+ +-------------+ +-------------+ +-------------+
+ | DMA | DMA32 | | NORMAL | | NORMAL | | NORMAL |
+ +-----+-------+ +-------------+ +-------------+ +-------------+
+
+In this case node 0 will span from 0 to 12 Gbytes and node 1 will span from
+4 to 16 Gbytes.
+
.. _nodes:
Nodes