From 4ae9f32eccef0e12ec7282889fc2a2e444b8ec4d Mon Sep 17 00:00:00 2001 From: Gage Eads Date: Thu, 20 Jun 2019 17:07:35 -0500 Subject: [PATCH] doc: add a note for multi-process in mempool guide 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: stable@dpdk.org Signed-off-by: Gage Eads Acked-by: Andrew Rybchenko --- doc/guides/prog_guide/mempool_lib.rst | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/doc/guides/prog_guide/mempool_lib.rst b/doc/guides/prog_guide/mempool_lib.rst index 52a569f576..3bb84b0a6f 100644 --- a/doc/guides/prog_guide/mempool_lib.rst +++ b/doc/guides/prog_guide/mempool_lib.rst @@ -133,6 +133,14 @@ 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 --------- -- 2.20.1