The mempool library assigns handler ops indexes based on the dynamic load
order of mempool handlers. Indexes are used so a mempool can be used by
multiple processes, but this only works if all processes agree on the
mapping from index to mempool handler.
When using the '-d' argument, it's possible for different processes to load
mempool handlers in different orders, and thus have different
index->handler mappings. Using a mempool in multiple of such processes will
result in undefined behavior.
This commit adds a note to the mempool library programmer's guide warning
users against this.
Fixes: 449c49b93a6b ("mempool: support handler operations")
Cc: [email protected]
Signed-off-by: Gage Eads <[email protected]>
---
doc/guides/prog_guide/mempool_lib.rst | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/doc/guides/prog_guide/mempool_lib.rst
b/doc/guides/prog_guide/mempool_lib.rst
index 52a569f57..4470f6b38 100644
--- a/doc/guides/prog_guide/mempool_lib.rst
+++ b/doc/guides/prog_guide/mempool_lib.rst
@@ -133,6 +133,13 @@ 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.
+ .. note::
+
+ When running a DPDK application with shared libraries, mempool handler
+ shared objects specified with the '-d' EAL command-line parameter are
+ dynamically loaded. When running a multi-process application with shared
+ libraries, the -d arguments for mempool handlers *must be specified in the
+ same order for all processes* to ensure correct operation.
Use Cases
---------
--
2.13.6
