memtx: apply review suggestions (part 1)

Apply review suggestions

Author: xuniq

doc/code_snippets/snippets/config/instances.enabled/memtx/config.yaml

@@ -1,8 +1,8 @@
 memtx:
-  memory: 100000000
+  memory: 1073741824
   allocator: 'small'
   min_tuple_size: 8
-  max_tuple_size: 1048576
+  max_tuple_size: 5242880
   slab_alloc_factor: 1.05
   slab_alloc_granularity: 8
   sort_threads: 256

doc/concepts/configuration/configuration_memtx.rst

@@ -9,40 +9,42 @@ In Tarantool, all data is stored in random-access memory (RAM) by default.
 For this purpose, the :ref:`memtx <engines-memtx>` storage engine is used.
 
 This topic describes how to define settings related to in-memory storage in the
-:ref:`memtx <configuration_reference_memtx>` section of a :ref:`YAML configuration <configuration>`.
+:ref:`memtx <configuration_reference_memtx>` section of a :ref:`YAML configuration <configuration>`
+-- for example, :ref:`memory size <configuration_reference_memtx_memory>` and :ref:`maximum tuple size <>configuration_reference_memtx_max_size`.
 
 ..  NOTE::
 
-    To calculate the required amount of memory, you can use the
+    To estimate the required amount of memory, you can use the
     `sizing calculator <https://www.tarantool.io/en/sizing_calculator/>`_.
 
 ..  _configuration_memtx-memory:
 
-Configure the memory size
--------------------------
+Memory size
+-----------
 
 In Tarantool, data is stored in spaces.
 Each space consists of tuples -- the database records.
-To specify the amount of memory that Tarantool allocates to actually store tuples, use the
-:ref:`memtx.memory <configuration_reference_snapshot_dir>` configuration option.
+To specify the amount of memory that Tarantool allocates to store tuples, use the
+:ref:`memtx.memory <configuration_reference_memtx_memory>` configuration option.
 
-In the example below, the memory size is 100000000 bytes, which is about 95 MB.
-The server does not exceeds this limit to allocate tuples.
-For indexes and connection information, the additional memory is used.
-
-When the ``memtx.memory`` limit is reached, ``INSERT`` or ``UPDATE`` requests fail with
-:ref:`ER_MEMORY_ISSUE <admin-troubleshoot-memory-issues>`.
+In the example below, the memory size is set to 1 GB (1073741824 bytes).
 
 ..  literalinclude:: /code_snippets/snippets/config/instances.enabled/memtx/config.yaml
     :language: yaml
     :start-at: memtx:
-    :end-at: 100000000
+    :end-at: 1073741824
     :dedent:
 
+The server does not exceed this limit to allocate tuples.
+For indexes and connection information, additional memory is used.
+
+When the ``memtx.memory`` limit is reached, ``INSERT`` or ``UPDATE`` requests fail with
+:ref:`ER_MEMORY_ISSUE <admin-troubleshoot-memory-issues>`.
+
 ..  _configuration_memtx-allocator:
 
-Specify the allocator type
---------------------------
+Allocator type
+--------------
 
 The allocators are the memory managers used for different purposes.
 To set the allocator type that manages memory for ``memtx`` tuples, use the :ref:`memtx.allocator <configuration_reference_memtx_allocator>`
@@ -64,14 +66,12 @@ The example below shows how to specify the ``small`` allocator type:
 
 ..  _configuration_memtx-min-max:
 
-Specify the size limitations of the allocation unit
----------------------------------------------------
+Tuple size
+----------
 
 You can configure the sizes of the smallest and the largest units to allocate.
 
-To set the minimum size in bytes, use the :ref:`memtx.min_tuple_size <configuration_reference_memtx_min_size>` configuration option.
-The setting can be useful if the tuples that you store are small.
-The minimum size is a value between 8 and 1048280 inclusive.
+To set the minimum size in bytes, use the :ref:`memtx.min_tuple_size <configuration_reference_memtx_min_size>` configuration option:
 
 ..  literalinclude:: /code_snippets/snippets/config/instances.enabled/memtx/config.yaml
     :language: yaml
@@ -80,19 +80,19 @@ The minimum size is a value between 8 and 1048280 inclusive.
     :dedent:
 
 To set the maximum size in bytes, use the :ref:`memtx.max_tuple_size <configuration_reference_memtx_max_size>` configuration option.
-The setting can be useful if the tuples that you store are large.
+In the example, the maximum size is set to 5 MB:
 
 ..  literalinclude:: /code_snippets/snippets/config/instances.enabled/memtx/config.yaml
     :language: yaml
     :start-at: max_tuple_size:
-    :end-at: 1048576
+    :end-at: 5242880
     :dedent:
 
 
 ..  _configuration_memtx-slab-alloc-granularity:
 
-Specify the granularity for slab allocation
--------------------------------------------
+Granularity for slab allocation
+-------------------------------
 
 If you use the :ref:`small <configuration_reference_memtx_allocator>` type of allocator, you can set the granularity of
 memory allocation in it.
@@ -115,10 +115,10 @@ In the example below, the value is increased to store different-sized tuples:
 
 ..  _configuration_memtx-slab-alloc-factor:
 
-Specify the slab allocation factor
-----------------------------------
+Slab allocation factor
+----------------------
 
-The size and number of memory pools depends on allocation factor and granularity.
+The size and number of memory pools depend on the allocation factor and granularity.
 The allocation factor is a multiplier used to calculate the sizes of memory chunks that tuples are stored in.
 To configure the allocation factor, use the :ref:`memtx.slab_alloc_factor <configuration_reference_memtx_slab_alloc_factor>`
 configuration option.
@@ -148,86 +148,3 @@ In the example, the maximum number of threads is used (256):
     :start-at: sort_threads:
     :end-at: 256
     :dedent:
-
-..  _configuration_memtx-statistics:
-
-Check the database statistics
------------------------------
-
-Tarantool provides the statistics about memory consumption for the given space or specific tuples.
-Available statistics:
-
-*   The amount of memory used for the :ref:`data of the specified space <configuration_memtx-statistics-space>`.
-*   The amount of :ref:`additional memory <configuration_memtx-statistics-additional>` used for the supplementary information.
-*   The :ref:`total memory usage <configuration_memtx-statistics-total>`.
-
-..  _configuration_memtx-statistics-space:
-
-Space
-~~~~~
-
-To get the get the amount of memory in bytes occupied by the specified space, use the :ref:`space_object:bsize() <box_space-bsize>` method.
-The function returns the total number of bytes in all tuples.
-
-..  code-block:: console
-
-    memtx:instance001> box.space.books:bsize()
-    ---
-    - 70348673
-    ...
-
-..  _configuration_memtx-statistics-additional:
-
-Additional memory
-~~~~~~~~~~~~~~~~~
-
-To check the usage of the additional memory, use the ``space_object:stat()`` method.
-The following information is provided:
-
--   ``header_size`` and ``field_map_size``: the size of service information.
--   ``data_size``: the actual size of data, which equals to ``space_object:bsize()``.
--   ``waste_size``: the size of memory wasted due to internal fragmentation in the `slab allocator <https://github.com/tarantool/small>`_.
-
-.. code-block:: console
-
-    memtx:instance001> box.space.books:stat()
-    ---
-    - tuple:
-        memtx:
-          waste_size: 1744011
-          data_size: 70348673
-          header_size: 2154132
-          field_map_size: 0
-        malloc:
-          waste_size: 0
-          data_size: 0
-          header_size: 0
-          field_map_size: 0
-    ...
-
-To get the usage of the additional memory (5 Mb) for the specified tuple, use ``tuple_object:info()``:
-
-.. code-block:: console
-
-    memtx:instance001> box.space.books:get('1853260622'):info()
-    ---
-    - data_size: 277
-      waste_size: 9
-      arena: memtx
-      field_map_size: 0
-      header_size: 10
-    ...
-
-..  _configuration_memtx-statistics-total:
-
-Total memory usage
-~~~~~~~~~~~~~~~~~~
-
-To get the total memory usage in bytes for the slab allocator, use the :ref:`box.slab.info() <box_slab_info>` function:
-
-..  code-block:: console
-
-    memtx:instance001> box.slab.info().items_used
-    ---
-    - 75302024
-    ...

doc/reference/configuration/cfg_storage.rst

@@ -22,7 +22,7 @@
 
     Since version 1.7.4.
 
-    How much memory Tarantool allocates to actually store tuples.
+    How much memory Tarantool allocates to store tuples.
     When the limit is reached, :ref:`INSERT <box_space-insert>` or
     :ref:`UPDATE <box_space-insert>` requests begin failing with
     error :errcode:`ER_MEMORY_ISSUE`. The server does not go beyond the
@@ -43,7 +43,6 @@
 
     Size of the largest allocation unit, for the memtx storage engine. It can be
     increased if it is necessary to store large tuples.
-    See also: :ref:`vinyl_max_tuple_size <cfg_storage-vinyl_max_tuple_size>`.
 
     | Type: integer
     | Default: 1024 * 1024 = 1048576 bytes
@@ -57,11 +56,11 @@
     Since version 1.7.4.
 
     Size of the smallest allocation unit. It can be decreased if most
-    of the tuples are very small. The value must be between 8 and 1048280
-    inclusive.
+    of the tuples are very small.
 
     | Type: integer
     | Default: 16 bytes
+    | Possible values: between 8 and 1048280 inclusive
     | Environment variable: TT_MEMTX_MIN_TUPLE_SIZE
     | Dynamic: no