vhost: add user callbacks for socket open/close

[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 613db88..d7ac677 100644 (file)
--- a/doc/guides/prog_guide/writing_efficient_code.rst
+++ b/doc/guides/prog_guide/writing_efficient_code.rst
@@ -105,6 +105,21 @@ 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.
 
 
 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
 ----------------------------
 
 Communication Between lcores
 ----------------------------
 


@@ -113,7 +128,7 @@ it is advised to use the DPDK ring API, which provides a lockless ring implement
 
 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
 
 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:
 Performance is greatly improved when using bulk access operations.
 
 The code algorithm that dequeues messages may be something similar to the following:


@@ -124,7 +139,7 @@ The code algorithm that dequeues messages may be something similar to the follow
 
     while (1) {
         /* Process as many elements as can be dequeued. */
 
     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;
 
         if (unlikely(count == 0))
             continue;