Signed-off-by: Mike Rapoport
Reviewed-by: Randy Dunlap
---
v2: address Matthew's feedback
Documentation/admin-guide/mm/concepts.rst | 51 ---
1 file changed, 26 insertions(+), 25 deletions(-)
diff --git a/Documentation/admin-guide/mm/concepts.rst
b/Documentation/admin-guide/mm/concepts.rst
index 291699c..c2531b1 100644
--- a/Documentation/admin-guide/mm/concepts.rst
+++ b/Documentation/admin-guide/mm/concepts.rst
@@ -4,13 +4,13 @@
Concepts overview
=
-The memory management in Linux is complex system that evolved over the
-years and included more and more functionality to support variety of
+The memory management in Linux is a complex system that evolved over the
+years and included more and more functionality to support a variety of
systems from MMU-less microcontrollers to supercomputers. The memory
-management for systems without MMU is called ``nommu`` and it
+management for systems without an MMU is called ``nommu`` and it
definitely deserves a dedicated document, which hopefully will be
eventually written. Yet, although some of the concepts are the same,
-here we assume that MMU is available and CPU can translate a virtual
+here we assume that an MMU is available and a CPU can translate a virtual
address to a physical address.
.. contents:: :local:
@@ -21,10 +21,10 @@ Virtual Memory Primer
The physical memory in a computer system is a limited resource and
even for systems that support memory hotplug there is a hard limit on
the amount of memory that can be installed. The physical memory is not
-necessary contiguous, it might be accessible as a set of distinct
+necessarily contiguous; it might be accessible as a set of distinct
address ranges. Besides, different CPU architectures, and even
-different implementations of the same architecture have different view
-how these address ranges defined.
+different implementations of the same architecture have different views
+of how these address ranges are defined.
All this makes dealing directly with physical memory quite complex and
to avoid this complexity a concept of virtual memory was developed.
@@ -48,8 +48,8 @@ appropriate kernel configuration option.
Each physical memory page can be mapped as one or more virtual
pages. These mappings are described by page tables that allow
-translation from virtual address used by programs to real address in
-the physical memory. The page tables organized hierarchically.
+translation from a virtual address used by programs to the physical
+memory address. The page tables are organized hierarchically.
The tables at the lowest level of the hierarchy contain physical
addresses of actual pages used by the software. The tables at higher
@@ -121,8 +121,8 @@ Nodes
Many multi-processor machines are NUMA - Non-Uniform Memory Access -
systems. In such systems the memory is arranged into banks that have
different access latency depending on the "distance" from the
-processor. Each bank is referred as `node` and for each node Linux
-constructs an independent memory management subsystem. A node has it's
+processor. Each bank is referred to as a `node` and for each node Linux
+constructs an independent memory management subsystem. A node has its
own set of zones, lists of free and used pages and various statistics
counters. You can find more details about NUMA in
:ref:`Documentation/vm/numa.rst ` and in
@@ -149,9 +149,9 @@ for program's stack and heap or by explicit calls to
mmap(2) system
call. Usually, the anonymous mappings only define virtual memory areas
that the program is allowed to access. The read accesses will result
in creation of a page table entry that references a special physical
-page filled with zeroes. When the program performs a write, regular
+page filled with zeroes. When the program performs a write, a regular
physical page will be allocated to hold the written data. The page
-will be marked dirty and if the kernel will decide to repurpose it,
+will be marked dirty and if the kernel decides to repurpose it,
the dirty page will be swapped out.
Reclaim
@@ -181,8 +181,8 @@ pressure.
The process of freeing the reclaimable physical memory pages and
repurposing them is called (surprise!) `reclaim`. Linux can reclaim
pages either asynchronously or synchronously, depending on the state
-of the system. When system is not loaded, most of the memory is free
-and allocation request will be satisfied immediately from the free
+of the system. When the system is not loaded, most of the memory is free
+and allocation requests will be satisfied immediately from the free
pages supply. As the load increases, the amount of the free pages goes
down and when it reaches a certain threshold (high watermark), an
allocation request will awaken the ``kswapd`` daemon. It will
@@ -190,7 +190,7 @@ asynchronously scan memory pages and either just free them
if the data
they contain is available elsewhere, or evict to the backing storage
