mbuf: introduce routine to get private mbuf pool flags

[dpdk.git] / doc / guides / prog_guide / writing_efficient_code.rst

diff --git a/doc/guides/prog_guide/writing_efficient_code.rst b/doc/guides/prog_guide/writing_efficient_code.rst
index 78d2afa..849f63e 100644 (file)
--- a/doc/guides/prog_guide/writing_efficient_code.rst
+++ b/doc/guides/prog_guide/writing_efficient_code.rst
@@ -1,32 +1,5 @@
-..  BSD LICENSE
-    Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
-    All rights reserved.
-
-    Redistribution and use in source and binary forms, with or without
-    modification, are permitted provided that the following conditions
-    are met:
-
-    * Redistributions of source code must retain the above copyright
-    notice, this list of conditions and the following disclaimer.
-    * Redistributions in binary form must reproduce the above copyright
-    notice, this list of conditions and the following disclaimer in
-    the documentation and/or other materials provided with the
-    distribution.
-    * Neither the name of Intel Corporation nor the names of its
-    contributors may be used to endorse or promote products derived
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-
-    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright(c) 2010-2014 Intel Corporation.
 
 Writing Efficient Code
 ======================
@@ -105,6 +78,21 @@ meaning that if all memory access operations are done on the first channel only,
 
 By default, the  :ref:`Mempool Library <Mempool_Library>` spreads the addresses of objects among memory channels.
 
+Locking memory pages
+~~~~~~~~~~~~~~~~~~~~
+
+The underlying operating system is allowed to load/unload memory pages at its own discretion.
+These page loads could impact the performance, as the process is on hold when the kernel fetches them.
+
+To avoid these you could pre-load, and lock them into memory with the ``mlockall()`` call.
+
+.. code-block:: c
+
+    if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
+        RTE_LOG(NOTICE, USER1, "mlockall() failed with error \"%s\"\n",
+                strerror(errno));
+    }
+
 Communication Between lcores
 ----------------------------
 
@@ -124,7 +112,7 @@ The code algorithm that dequeues messages may be something similar to the follow
 
     while (1) {
         /* Process as many elements as can be dequeued. */
-        count = rte_ring_dequeue_burst(ring, obj_table, MAX_BULK);
+        count = rte_ring_dequeue_burst(ring, obj_table, MAX_BULK, NULL);
         if (unlikely(count == 0))
             continue;