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Diffstat (limited to 'Documentation/mm/physical_memory.rst')
| -rw-r--r-- | Documentation/mm/physical_memory.rst | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/Documentation/mm/physical_memory.rst b/Documentation/mm/physical_memory.rst index 1bc888d36ea1..531e73b003dd 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 |