[dpdk-dev] [PATCH 0/5] add external mempool manager

David Hunt david.hunt at intel.com
Tue Jan 26 18:25:50 CET 2016

Hi all on the list.

Here's a proposed patch for an external mempool manager

The External Mempool Manager is an extension to the mempool API that allows
users to add and use an external mempool manager, which allows external memory
subsystems such as external hardware memory management systems and software
based memory allocators to be used with DPDK.

The existing API to the internal DPDK mempool manager will remain unchanged
and will be backward compatible.

There are two aspects to external mempool manager.
  1. Adding the code for your new mempool handler. This is achieved by adding a
     new mempool handler source file into the librte_mempool library, and
     using the REGISTER_MEMPOOL_HANDLER macro.
  2. Using the new API to call rte_mempool_create_ext to create a new mempool
     using the name parameter to identify which handler to use.

New API calls added
 1. A new mempool 'create' function which accepts mempool handler name.
 2. A new mempool 'rte_get_mempool_handler' function which accepts mempool
    handler name, and returns the index to the relevant set of callbacks for
    that mempool handler

Several external mempool managers may be used in the same application. A new
mempool can then be created by using the new 'create' function, providing the
mempool handler name to point the mempool to the relevant mempool manager
callback structure.

The old 'create' function can still be called by legacy programs, and will
internally work out the mempool handle based on the flags provided (single
producer, single consumer, etc). By default handles are created internally to
implement the built-in DPDK mempool manager and mempool types.

The external mempool manager needs to provide the following functions.
 1. alloc     - allocates the mempool memory, and adds each object onto a ring
 2. put       - puts an object back into the mempool once an application has
                finished with it
 3. get       - gets an object from the mempool for use by the application
 4. get_count - gets the number of available objects in the mempool
 5. free      - frees the mempool memory

Every time a get/put/get_count is called from the application/PMD, the
callback for that mempool is called. These functions are in the fastpath,
and any unoptimised handlers may limit performance.

The new APIs are as follows:

1. rte_mempool_create_ext

struct rte_mempool *
rte_mempool_create_ext(const char * name, unsigned n,
        unsigned cache_size, unsigned private_data_size,
        int socket_id, unsigned flags,
        const char * handler_name);

2. rte_get_mempool_handler

rte_get_mempool_handler(const char *name);

Please see rte_mempool.h for further information on the parameters.

The important thing to note is that the mempool handler is passed by name
to rte_mempool_create_ext, and that in turn calls rte_get_mempool_handler to
get the handler index, which is stored in the rte_memool structure. This
allow multiple processes to use the same mempool, as the function pointers
are accessed via handler index.

The mempool handler structure contains callbacks to the implementation of
the handler, and is set up for registration as follows:

static struct rte_mempool_handler handler_sp_mc = {
    .name = "ring_sp_mc",
    .alloc = rte_mempool_common_ring_alloc,
    .put = common_ring_sp_put,
    .get = common_ring_mc_get,
    .get_count = common_ring_get_count,
    .free = common_ring_free,

And then the following macro will register the handler in the array of handlers


For and example of a simple malloc based mempool manager, see

For an example of API usage, please see app/test/test_ext_mempool.c, which
implements a rudimentary mempool manager using simple mallocs for each
mempool object (custom_mempool.c).

David Hunt (5):
  mempool: add external mempool manager support
  memool: add stack (lifo) based external mempool handler
  mempool: add custom external mempool handler example
  mempool: add autotest for external mempool custom example
  mempool: allow rte_pktmbuf_pool_create switch between memool handlers

 app/test/Makefile                         |   1 +
 app/test/test_ext_mempool.c               | 470 ++++++++++++++++++++++++++++++
 app/test/test_mempool_perf.c              |   2 -
 lib/librte_mbuf/rte_mbuf.c                |  11 +
 lib/librte_mempool/Makefile               |   3 +
 lib/librte_mempool/custom_mempool.c       | 158 ++++++++++
 lib/librte_mempool/rte_mempool.c          | 208 +++++++++----
 lib/librte_mempool/rte_mempool.h          | 205 +++++++++++--
 lib/librte_mempool/rte_mempool_default.c  | 229 +++++++++++++++
 lib/librte_mempool/rte_mempool_internal.h |  70 +++++
 lib/librte_mempool/rte_mempool_stack.c    | 162 ++++++++++
 11 files changed, 1430 insertions(+), 89 deletions(-)
 create mode 100644 app/test/test_ext_mempool.c
 create mode 100644 lib/librte_mempool/custom_mempool.c
 create mode 100644 lib/librte_mempool/rte_mempool_default.c
 create mode 100644 lib/librte_mempool/rte_mempool_internal.h
 create mode 100644 lib/librte_mempool/rte_mempool_stack.c


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