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Diffstat (limited to 'doc/guides/prog_guide/mempool_lib.rst')
| -rw-r--r-- | doc/guides/prog_guide/mempool_lib.rst | 42 |
1 files changed, 37 insertions, 5 deletions
diff --git a/doc/guides/prog_guide/mempool_lib.rst b/doc/guides/prog_guide/mempool_lib.rst index 5fae79ab..59466752 100644 --- a/doc/guides/prog_guide/mempool_lib.rst +++ b/doc/guides/prog_guide/mempool_lib.rst @@ -34,13 +34,12 @@ Mempool Library =============== A memory pool is an allocator of a fixed-sized object. -In the DPDK, it is identified by name and uses a ring to store free objects. +In the DPDK, it is identified by name and uses a mempool handler to store free objects. +The default mempool handler is ring based. It provides some other optional services such as a per-core object cache and an alignment helper to ensure that objects are padded to spread them equally on all DRAM or DDR3 channels. -This library is used by the -:ref:`Mbuf Library <Mbuf_Library>` and the -:ref:`Environment Abstraction Layer <Environment_Abstraction_Layer>` (for logging history). +This library is used by the :ref:`Mbuf Library <Mbuf_Library>`. Cookies ------- @@ -116,7 +115,7 @@ While this may mean a number of buffers may sit idle on some core's cache, the speed at which a core can access its own cache for a specific memory pool without locks provides performance gains. The cache is composed of a small, per-core table of pointers and its length (used as a stack). -This cache can be enabled or disabled at creation of the pool. +This internal cache can be enabled or disabled at creation of the pool. The maximum size of the cache is static and is defined at compilation time (CONFIG_RTE_MEMPOOL_CACHE_MAX_SIZE). @@ -128,6 +127,39 @@ The maximum size of the cache is static and is defined at compilation time (CONF A mempool in Memory with its Associated Ring +Alternatively to the internal default per-lcore local cache, an application can create and manage external caches through the ``rte_mempool_cache_create()``, ``rte_mempool_cache_free()`` and ``rte_mempool_cache_flush()`` calls. +These user-owned caches can be explicitly passed to ``rte_mempool_generic_put()`` and ``rte_mempool_generic_get()``. +The ``rte_mempool_default_cache()`` call returns the default internal cache if any. +In contrast to the default caches, user-owned caches can be used by non-EAL threads too. + +Mempool Handlers +------------------------ + +This allows external memory subsystems, such as external hardware memory +management systems and software based memory allocators, to be used with DPDK. + +There are two aspects to a mempool handler. + +* Adding the code for your new mempool operations (ops). This is achieved by + adding a new mempool ops code, and using the ``REGISTER_MEMPOOL_OPS`` macro. + +* Using the new API to call ``rte_mempool_create_empty()`` and + ``rte_mempool_set_ops_byname()`` to create a new mempool and specifying which + ops to use. + +Several different mempool handlers may be used in the same application. A new +mempool can be created by using the ``rte_mempool_create_empty()`` function, +then using ``rte_mempool_set_ops_byname()`` to point the mempool to the +relevant mempool handler callback (ops) structure. + +Legacy applications may continue to use the old ``rte_mempool_create()`` API +call, which uses a ring based mempool handler by default. These applications +will need to be modified to use a new mempool handler. + +For applications that use ``rte_pktmbuf_create()``, there is a config setting +(``RTE_MBUF_DEFAULT_MEMPOOL_OPS``) that allows the application to make use of +an alternative mempool handler. + Use Cases --------- |