docs: remove description of DISCONTIGMEM

Remove description of DISCONTIGMEM from the "Memory Models" document and
update VM sysctl description so that it won't mention DISCONIGMEM.

Link: https://lkml.kernel.org/r/20210608091316.3622-8-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst
index 2da2573..8387ad0 100644 (file)
--- a/Documentation/admin-guide/sysctl/vm.rst
+++ b/Documentation/admin-guide/sysctl/vm.rst
@@ -938,12 +938,12 @@ allocations, THP and hugetlbfs pages.
 
 To make it sensible with respect to the watermark_scale_factor
 parameter, the unit is in fractions of 10,000. The default value of
 
 To make it sensible with respect to the watermark_scale_factor
 parameter, the unit is in fractions of 10,000. The default value of

-15,000 on !DISCONTIGMEM configurations means that up to 150% of the high
-watermark will be reclaimed in the event of a pageblock being mixed due
-to fragmentation. The level of reclaim is determined by the number of
-fragmentation events that occurred in the recent past. If this value is
-smaller than a pageblock then a pageblocks worth of pages will be reclaimed
-(e.g.  2MB on 64-bit x86). A boost factor of 0 will disable the feature.
+15,000 means that up to 150% of the high watermark will be reclaimed in the
+event of a pageblock being mixed due to fragmentation. The level of reclaim
+is determined by the number of fragmentation events that occurred in the
+recent past. If this value is smaller than a pageblock then a pageblocks
+worth of pages will be reclaimed (e.g.  2MB on 64-bit x86). A boost factor
+of 0 will disable the feature.

 
 
 watermark_scale_factor
 
 
 watermark_scale_factor

diff --git a/Documentation/vm/memory-model.rst b/Documentation/vm/memory-model.rst
index ce398a7..30e8fbe 100644 (file)
--- a/Documentation/vm/memory-model.rst
+++ b/Documentation/vm/memory-model.rst
@@ -14,15 +14,11 @@ for the CPU. Then there could be several contiguous ranges at
 completely distinct addresses. And, don't forget about NUMA, where
 different memory banks are attached to different CPUs.
 
 completely distinct addresses. And, don't forget about NUMA, where
 different memory banks are attached to different CPUs.
 

-Linux abstracts this diversity using one of the three memory models:
-FLATMEM, DISCONTIGMEM and SPARSEMEM. Each architecture defines what
+Linux abstracts this diversity using one of the two memory models:
+FLATMEM and SPARSEMEM. Each architecture defines what

 memory models it supports, what the default memory model is and
 whether it is possible to manually override that default.
 
 memory models it supports, what the default memory model is and
 whether it is possible to manually override that default.
 

-.. note::
-   At time of this writing, DISCONTIGMEM is considered deprecated,
-   although it is still in use by several architectures.
-

 All the memory models track the status of physical page frames using
 struct page arranged in one or more arrays.
 
 All the memory models track the status of physical page frames using
 struct page arranged in one or more arrays.
 


@@ -63,43 +59,6 @@ straightforward: `PFN - ARCH_PFN_OFFSET` is an index to the
 The `ARCH_PFN_OFFSET` defines the first page frame number for
 systems with physical memory starting at address different from 0.
 
 The `ARCH_PFN_OFFSET` defines the first page frame number for
 systems with physical memory starting at address different from 0.
 

-DISCONTIGMEM
-============
-
-The DISCONTIGMEM model treats the physical memory as a collection of
-`nodes` similarly to how Linux NUMA support does. For each node Linux
-constructs an independent memory management subsystem represented by
-`struct pglist_data` (or `pg_data_t` for short). Among other
-things, `pg_data_t` holds the `node_mem_map` array that maps
-physical pages belonging to that node. The `node_start_pfn` field of
-`pg_data_t` is the number of the first page frame belonging to that
-node.
-
-The architecture setup code should call :c:func:`free_area_init_node` for
-each node in the system to initialize the `pg_data_t` object and its
-`node_mem_map`.
-
-Every `node_mem_map` behaves exactly as FLATMEM's `mem_map` -
-every physical page frame in a node has a `struct page` entry in the
-`node_mem_map` array. When DISCONTIGMEM is enabled, a portion of the
-`flags` field of the `struct page` encodes the node number of the
-node hosting that page.
-
-The conversion between a PFN and the `struct page` in the
-DISCONTIGMEM model became slightly more complex as it has to determine
-which node hosts the physical page and which `pg_data_t` object
-holds the `struct page`.
-
-Architectures that support DISCONTIGMEM provide :c:func:`pfn_to_nid`
-to convert PFN to the node number. The opposite conversion helper
-:c:func:`page_to_nid` is generic as it uses the node number encoded in
-page->flags.
-
-Once the node number is known, the PFN can be used to index
-appropriate `node_mem_map` array to access the `struct page` and
-the offset of the `struct page` from the `node_mem_map` plus
-`node_start_pfn` is the PFN of that page.
-

 SPARSEMEM
 =========
 
 SPARSEMEM
 =========