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doc: add external memory feature

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Document the addition of external memory support to DPDK.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
This commit is contained in:
Anatoly Burakov 2018-10-02 14:34:58 +01:00 committed by Thomas Monjalon
parent c7f5dba7d4
commit 66498f0ffe
2 changed files with 43 additions and 0 deletions
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37
doc/guides/prog_guide/env_abstraction_layer.rst
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@ -213,6 +213,43 @@ Normally, these options do not need to be changed.
can later be mapped into that preallocated VA space (if dynamic memory mode
is enabled), and can optionally be mapped into it at startup.
Support for Externally Allocated Memory
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It is possible to use externally allocated memory in DPDK, using a set of malloc
heap API's. Support for externally allocated memory is implemented through
overloading the socket ID - externally allocated heaps will have socket ID's
that would be considered invalid under normal circumstances. Requesting an
allocation to take place from a specified externally allocated memory is a
matter of supplying the correct socket ID to DPDK allocator, either directly
(e.g. through a call to ``rte_malloc``) or indirectly (through data
structure-specific allocation API's such as ``rte_ring_create``).
Since there is no way DPDK can verify whether memory are is available or valid,
this responsibility falls on the shoulders of the user. All multiprocess
synchronization is also user's responsibility, as well as ensuring that all
calls to add/attach/detach/remove memory are done in the correct order. It is
not required to attach to a memory area in all processes - only attach to memory
areas as needed.
The expected workflow is as follows:
* Get a pointer to memory area
* Create a named heap
* Add memory area(s) to the heap
- If IOVA table is not specified, IOVA addresses will be assumed to be
unavailable, and DMA mappings will not be performed
- Other processes must attach to the memory area before they can use it
* Get socket ID used for the heap
* Use normal DPDK allocation procedures, using supplied socket ID
* If memory area is no longer needed, it can be removed from the heap
- Other processes must detach from this memory area before it can be removed
* If heap is no longer needed, remove it
- Socket ID will become invalid and will not be reused
For more information, please refer to ``rte_malloc`` API documentation,
specifically the ``rte_malloc_heap_*`` family of function calls.
PCI Access
~~~~~~~~~~

6
doc/guides/rel_notes/release_18_11.rst
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@ -54,6 +54,12 @@ New Features
Also, make sure to start the actual text at the margin.
=========================================================
* **Added support for using externally allocated memory in DPDK.**
DPDK has gained support for creating new ``rte_malloc`` heaps referencing
memory that was created outside of DPDK's own page allocator, and using that
memory natively with any other DPDK library or data structure.
* **Add support to offload more flow match and actions for CXGBE PMD**
Flow API support has been enhanced for CXGBE Poll Mode Driver to offload: