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From: Gage Eads <gage.eads@intel.com>
To: dev@dpdk.org
Cc: arybchenko@solarflare.com,
olivier.matz@6wind.com,
stable@dpdk.org
Date: Thu, 20 Jun 2019 17:07:35 -0500
Message-Id: <20190620220735.6583-1-gage.eads@intel.com>
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Subject: [dpdk-dev] [PATCH v2] doc: add multi-proc shared lib mempool note
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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 <gage.eads@intel.com>
Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>
---
doc/guides/prog_guide/mempool_lib.rst | 8 ++++++++
1 file changed, 8 insertions(+)
v2: add another empty line
diff --git a/doc/guides/prog_guide/mempool_lib.rst b/doc/guides/prog_guide/mempool_lib.rst
index 52a569f57..3bb84b0a6 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
---------
--
2.13.6