-.. 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
- from this software without specific prior written permission.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.. SPDX-License-Identifier: BSD-3-Clause
+ Copyright(c) 2010-2014 Intel Corporation.
Writing Efficient Code
======================
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
----------------------------
The ring supports bulk and burst access,
meaning that it is possible to read several elements from the ring with only one costly atomic operation
-(see Chapter 5 "Ring Library").
+(see :doc:`ring_lib`).
Performance is greatly improved when using bulk access operations.
The code algorithm that dequeues messages may be something similar to the following:
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;
The DPDK supports CPU microarchitecture-specific optimizations by means of CONFIG_RTE_MACHINE option
in the DPDK configuration file.
-The degree of optimization depends on the compiler's ability to optimize for a specitic microarchitecture,
+The degree of optimization depends on the compiler's ability to optimize for a specific microarchitecture,
therefore it is preferable to use the latest compiler versions whenever possible.
If the compiler version does not support the specific feature set (for example, the IntelĀ® AVX instruction set),