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Diffstat (limited to 'Documentation/admin-guide/mm/concepts.rst')
| -rw-r--r-- | Documentation/admin-guide/mm/concepts.rst | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/Documentation/admin-guide/mm/concepts.rst b/Documentation/admin-guide/mm/concepts.rst index c2531b14bf46..e796b0a7e4a5 100644 --- a/Documentation/admin-guide/mm/concepts.rst +++ b/Documentation/admin-guide/mm/concepts.rst @@ -1,5 +1,3 @@ -.. _mm_concepts: - ================= Concepts overview ================= @@ -35,7 +33,7 @@ physical memory (demand paging) and provides a mechanism for the protection and controlled sharing of data between processes. With virtual memory, each and every memory access uses a virtual -address. When the CPU decodes the an instruction that reads (or +address. When the CPU decodes an instruction that reads (or writes) from (or to) the system memory, it translates the `virtual` address encoded in that instruction to a `physical` address that the memory controller can understand. @@ -86,16 +84,15 @@ memory with the huge pages. The first one is `HugeTLB filesystem`, or hugetlbfs. It is a pseudo filesystem that uses RAM as its backing store. For the files created in this filesystem the data resides in the memory and mapped using huge pages. The hugetlbfs is described at -:ref:`Documentation/admin-guide/mm/hugetlbpage.rst <hugetlbpage>`. +Documentation/admin-guide/mm/hugetlbpage.rst. Another, more recent, mechanism that enables use of the huge pages is called `Transparent HugePages`, or THP. Unlike the hugetlbfs that requires users and/or system administrators to configure what parts of the system memory should and can be mapped by the huge pages, THP manages such mappings transparently to the user and hence the -name. See -:ref:`Documentation/admin-guide/mm/transhuge.rst <admin_guide_transhuge>` -for more details about THP. +name. See Documentation/admin-guide/mm/transhuge.rst for more details +about THP. Zones ===== @@ -125,8 +122,8 @@ 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 <numa>` and in -:ref:`Documentation/admin-guide/mm/numa_memory_policy.rst <numa_memory_policy>`. +Documentation/mm/numa.rst` and in +Documentation/admin-guide/mm/numa_memory_policy.rst. Page cache ========== @@ -184,7 +181,7 @@ pages either asynchronously or synchronously, depending on the state 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 +down and when it reaches a certain threshold (low watermark), an allocation request will awaken the ``kswapd`` daemon. It will asynchronously scan memory pages and either just free them if the data they contain is available elsewhere, or evict to the backing storage |