[dpdk-dev] [PATCH v1 1/5] doc: add performance-thread sample application guide

[ibetts <ian.betts@intel.com>]

From: Ian Betts <ian.betts@intel.com>

This commit adds documentation for the performance-thread
sample application.

Signed-off-by: Ian Betts <ian.betts@intel.com>
---
 doc/guides/rel_notes/release_2_2.rst            |    6 +
 doc/guides/sample_app_ug/index.rst              |    1 +
 doc/guides/sample_app_ug/performance_thread.rst | 1221 +++++++++++++++++++++++
 3 files changed, 1228 insertions(+)
 create mode 100644 doc/guides/sample_app_ug/performance_thread.rst

diff --git a/doc/guides/rel_notes/release_2_2.rst b/doc/guides/rel_notes/release_2_2.rst
index 5687676..e9772d3 100644
--- a/doc/guides/rel_notes/release_2_2.rst
+++ b/doc/guides/rel_notes/release_2_2.rst
@@ -52,6 +52,12 @@ Libraries
 Examples
 ~~~~~~~~
 
+* **examples: Introducing a performance thread example**
+
+  This an l3fwd derivative focused to enable characterization of performance
+  with different threading models, including multiple EAL threads per physical
+  core, and multiple Lightweight threads running in an EAL thread.
+  The examples includes a simple cooperative scheduler.
 
 Other
 ~~~~~
diff --git a/doc/guides/sample_app_ug/index.rst b/doc/guides/sample_app_ug/index.rst
index 9beedd9..70d4a5c 100644
--- a/doc/guides/sample_app_ug/index.rst
+++ b/doc/guides/sample_app_ug/index.rst
@@ -73,6 +73,7 @@ Sample Applications User Guide
     vm_power_management
     tep_termination
     proc_info
+    performance_thread
 
 **Figures**
 
diff --git a/doc/guides/sample_app_ug/performance_thread.rst b/doc/guides/sample_app_ug/performance_thread.rst
new file mode 100644
index 0000000..497d729
--- /dev/null
+++ b/doc/guides/sample_app_ug/performance_thread.rst
@@ -0,0 +1,1220 @@
+..  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:
+
+    * Re-distributions 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.
+
+
+Performance Thread Sample Application
+=====================================
+
+The performance thread sample application is a derivative of the standard L3
+forwarding application that demonstrates different threading models.
+
+Overview
+--------
+For a general description of the L3 forwarding applications capabilities
+please refer to the documentation of the standard application in
+:doc:`l3_forward`.
+
+The performance thread sample application differs from the standard L3 forward
+example in that it divides the TX and Rx processing between different threads,
+and makes it possible to assign individual threads to different cores.
+
+Three threading models are considered:-
+
+#.  When there is EAL thread per physical core
+#.  When there are multiple EAL threads per physical core
+#.  When there are multiple lightweight threads per EAL thread
+
+Since DPDK release 2.0 it is possible to launch applications using the –lcores
+EAL parameter, specifying CPU sets for a physical core. With the  performance
+thread sample application its is now also possible to assign individual Rx
+and TX functions to different cores.
+
+As an alternative to dividing the L3 forwarding work between different EAL
+threads the performance thread sample introduces the possibility to run the
+application threads as lightweight threads (L-threads) within one or
+more EAL threads.
+
+In order to facilitate this threading model the example includes a primitive
+cooperative scheduler (L-thread) subsystem. More details of the L-thread
+subsystem can be found in :ref:`lthread_subsystem`
+
+**Note:** Whilst theoretcially possible it is not anticipated that multiple
+L-thread schedulers would be run on the same physical core, this mode of
+operataion should not be expected to yield useful performance and is considered
+invalid.
+
+Compiling the Application
+-------------------------
+The application is located in the sample application in the
+performance-thread folder.
+
+#.  Go to the example applications folder
+
+    .. code-block:: console
+
+       export RTE_SDK=/path/to/rte_sdk cd ${RTE_SDK}/examples/performance-thread/l3fwd-thread
+
+#.  Set the target (a default target is used if not specified). For example:
+
+    .. code-block:: console
+
+       export RTE_TARGET=x86_64-native-linuxapp-gcc
+
+    See the DPDK Getting Started Guide for possible RTE_TARGET values.
+
+#.  Build the application:
+
+	make
+
+
+
+Running the Application
+-----------------------
+
+The application has a number of command line options:
+
+.. code-block:: console
+
+    ./build/l3fwd-thread [EAL options] -- -p PORTMASK [-P] --rx(port,queue,lcore,thread)[,(port,queue,lcore,thread)] --tx(port,lcore,thread)[,(port,lcore,thread)] [--enable-jumbo [--max-pkt-len PKTLEN]]  [--no-numa][--hash-entry-num][--ipv6] [--no-lthreads]
+
+where,
+
+*   -p PORTMASK: Hexadecimal bitmask of ports to configure
+
+*   -P: optional, sets all ports to promiscuous mode so that packets are
+     accepted regardless of the packet's Ethernet MAC destination address.
+     Without this option, only packets with the Ethernet MAC destination
+     address set to the Ethernet address of the port are accepted.
+
+*   --rx (port,queue,lcore,thread)[,(port,queue,lcore,thread)]:
+	the list of NIC RX ports and queues handled by the RX lcores and threads
+
+*   --tx (port,lcore,thread)[,(port,lcore,thread)]:
+	the list of NIC TX ports handled by the I/O TX lcores and threads.
+
+*   --enable-jumbo: optional, enables jumbo frames
+
+*   --max-pkt-len: optional, maximum packet length in decimal (64-9600)
+
+*   --no-numa: optional, disables numa awareness
+
+*   --hash-entry-num: optional, specifies the hash entry number in hex to be setup
+
+*   --ipv6: optional, set it if running ipv6 packets
+
+*   --no-lthreads: optional, disables lthread model and uses EAL threading model
+
+The l3fwd-threads application allows you to start packet processing in two threading
+models: L-Threads (default) and EAL Threads (when "--no-lthreads" parameter is used).
+For consistency all parameters are used the same way for both models.
+
+* rx  parameters
+
+.. _table_l3fwd_rx_parameters:
+
++--------+------------------------------------------------------+
+| port   | rx port                                              |
++--------+------------------------------------------------------+
+| queue  | rx queue that will be read on the specified rx port  |
++--------+------------------------------------------------------+
+| lcore  | core to use for the thread                           |
++--------+------------------------------------------------------+
+| thread | thread id (continuously from 0 to N)                 |
++--------+------------------------------------------------------+
+
+
+* tx parameters
+
+.. _table_l3fwd_tx_parameters:
+
++--------+------------------------------------------------------+
+| port   | default port to transmit (if lookup fails nor found) |
++--------+------------------------------------------------------+
+| lcore  | core to use for L3 route match and transmit          |
++--------+------------------------------------------------------+
+| thread | thread id (continuously from 0 to N)                 |
++--------+------------------------------------------------------+
+
+
+
+Running with L-threads
+~~~~~~~~~~~~~~~~~~~~~~
+
+When the L-thread model is used (default option), lcore and thread parameters in
+--rx/--tx are used to affine threads to the selected scheduler using the rules:
+
+**If lcores are the same, l-threads are placed on the same scheduler**
+
+**If both lcore and l-thread id are the same, only one l-thread is used and
+queues / rings are polled inside it**
+
+e.g.
+
+
+    .. code-block:: console
+
+l3fwd-thread -c ff -n 2 -- -P -p 3 \
+        --rx="(0,0,0,0)(1,0,1,1)" \
+        --tx="(0,2,0)(1,3,1)(0,4,2)(1,5,3)(0,6,4)(1,7,5)"
+
+Places every l-thread on different lcore
+
+    .. code-block:: console
+
+l3fwd-thread -c ff -n 2 -- -P -p 3 \
+        --rx="(0,0,0,0)(1,0,0,1)" \
+        --tx="(0,1,0)(1,1,1)(0,2,2)(1,2,3)"
+
+Places rx lthreads on lcore 0 and tx l-threads on lcore 1 and 2
+
+and so on.
+
+Running with EAL threads
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+When --no-lthreads parameter is used, L-threading model is turned off and EAL
+threads are used for all processing. EAL Threads are enumerated in the same way as L-threads,
+but --lcores EAL parameter is used to affine thread to the selected cpu-set (scheduler).
+
+Thus it is possible to place every Rx and TX thread on different lcores
+a) If lcore id is the same, only one EAL thread is used and queues / rings are
+polled inside it.
+
+e.g.
+
+    .. code-block:: console
+
+l3fwd-thread -c ff -n 2 -- -P -p 3 \
+        --rx="(0,0,0,0)(1,0,1,1)" \
+        --tx="(0,2,0)(1,3,1)(0,4,2)(1,5,3)(0,6,4)(1,7,5)" \
+	--no-lthreads
+
+Places every EAL thread on different lcore.
+
+To affine two ore more EAL threads to one cpu-set, eal --lcores parameter is used
+
+    .. code-block:: console
+
+l3fwd-thread -c ff -n 2 --lcores="(0,1)@0,(2,3)@1,(4,5)@2" -- -P -p 3 \
+        --rx="(0,0,0,0)(1,0,1,1)" \
+        --tx="(0,2,0)(1,3,1)(0,4,2)(1,5,3)" \
+	--no-lthreads
+
+Places rx EAL threads on lcore 0 and tx eal threads on lcore 1 and 2 and so on.
+
+
+Examples
+~~~~~~~~
+
+For selected scenarios the command line configuration of the application for L-Threads
+and its corresponding EAL Threads command line can be realized as follows:
+
+a) Start every thread on different scheduler (1:1)
+
+    .. code-block:: console
+
+l3fwd-thread -c ff -n 2 -- -P -p 3 \
+	--rx="(0,0,0,0)(0,1,1,1)(1,0,2,2)(0,1,3,3)" \
+	--tx="(0,4,0)(1,5,1)"
+
+    .. code-block:: console
+
+l3fwd-thread -c ff -n 2 -- -P -p 3 \
+		--rx="(0,0,0,0)(0,1,1,1)(1,0,2,2)(0,1,3,3)" \
+		--tx="(0,4,0)(1,5,1)" \
+		--no-lthreads
+
+b) Start all threads on one scheduler (N:1)
+
+    .. code-block:: console
+
+l3fwd-thread -c ff -n 2 -- -P -p 3 \
+		--rx="(0,0,0,0)(0,1,0,1)(1,0,0,2)(0,1,0,3)" \
+		--tx="(0,0,0)(1,0,1)"
+
+Example above, starts 6 L-threads on lcore 0.
+
+    .. code-block:: console
+
+l3fwd-thread -c ff -n 2 --lcores="(0-5)@0" -- -P -p 3 \
+		--rx="(0,0,0,0)(0,1,1,1)(1,0,2,2)(0,1,3,3)" \
+		--tx="(0,4,0)(1,5,1)" \
+		--no-lthreads
+
+Example above, starts 6 EAL threads on cpu-set 0.
+
+
+c) Start threads on different schedulers (N:M)
+
+    .. code-block:: console
+
+l3fwd-thread -c ff -n 2 -- -P -p 3 \
+		--rx="(0,0,0,0)(0,1,0,1)(1,0,0,2)(0,1,0,3)" \
+		--tx="(0,1,0)(1,1,1)"
+
+Example above, starts 4 L-threads (0,1,2,3) for rx on lcore 0, and 2 L-threads
+for tx on lcore 1.
+
+    .. code-block:: console
+
+l3fwd-thread -c ff -n 2 --lcores="(0-3)@0,(4,5)@1" -- -P -p 3 \
+		--rx="(0,0,0,0)(0,1,1,1)(1,0,2,2)(0,1,3,3)" \
+		--tx="(0,4,0)(1,5,1)" \
+		--no-lthreads
+
+Example above, starts 4 EAL threads (0,1,2,3) for rx on cpu-set 0, and
+2 EAL threads for tx on cpu-set 1.
+
+
+Explanation
+-----------
+
+To a great extent the sample application differs little from the standard L3
+forwarding application, and readers are advised to familiarize themselves with the
+material covered in the :doc:`l3_forward` documentation before proceeding.
+
+The following explanation is focused on the way threading is handled in the
+performance thread example.
+
+
+Mode of operation with EAL threads
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The performance thread sample application has split the Rx and TX functionality
+into two different threads, and the pairs of Rx and TX threads are
+interconnected via software rings. With respect to these rings the Rx threads
+are producers and the TX threads are consumers.
+
+On initialization the tx and rx threads are started according to the command
+line parameters.
+
+The Rx threads poll the network interface queues and post received packets to a
+TX thread via the corresponding software ring.
+
+The TX threads poll software rings, perform the L3 forwarding hash/LPM match,
+and assemble packet bursts before performing burst transmit on the network
+interface.
+
+As with the standard L3 forward application, burst draining of residual packets
+is performed periodically with the period calculated from elapsed time using
+the timestamps counter.
+
+
+Mode of operation with L-threads
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Like the EAL thread configuration the application has split the Rx and TX
+functionality into different threads, and the pairs of Rx and TX threads are
+interconnected via software rings.
+
+On initialization an L-thread scheduler is started on every EAL thread. On all
+but the master EAL thread only a a dummy L-thread is initially started.
+The L-thread started on the master EAL thread then spawns other L-threads on
+different L-thread shedulers according the the command line parameters.
+
+The Rx threads poll the network interface queues and post received packets
+to a TX thread via the corresponding software ring.
+
+The ring interface is augmented by means of an L-thread condition variable that
+enables the TX thread to be suspended when the TX ring is empty. The Rx thread
+signals the condition whenever it posts to the TX ring, causing the TX thread
+to be resumed.
+
+Additionally the TX L-thread spawns a worker L-thread to take care of
+polling the software rings, whilst it handles burst draining of the transmit
+buffer.
+
+The worker threads poll the software rings, perform L3 route lookup and
+assemble packet bursts. If the TX ring is empty the worker thread suspends
+itself by waiting on the condition variable associated with the ring.
+
+Burst draining of residual packets is performed by the  TX thread which sleeps
+(using an L-thread sleep function) and resumes periodically to flush the TX
+buffer.
+
+This design means that L-threads that have no work, can yield the CPU to other
+L-threads and avoid having to constantly poll the software rings.
+
+
+.. _lthread_subsystem:
+
+The L-thread subsystem
+----------------------
+The L-thread subsystem resides in the examples/performance-thread/common
+directory and is built and linked automatically when building the l3fwd-lthread
+example.
+
+The subsystem provides a simple cooperative scheduler to enable arbitrary
+functions to run as cooperative threads within a single EAL thread.
+The subsystem provides a pthread like API that is intended to assist in
+reuse of legacy code written for POSIX pthreads.
+
+The following sections provide some detail on the features, constraints,
+performance and porting considerations when using L-threads.
+
+.. _comparison_between_lthreads_and_pthreads:
+
+Comparison between L-threads and POSIX pthreads
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The fundamental difference between the L-thread and pthread models is the
+way which threads are scheduled. The simplest way to think about this is to
+consider the case of a processor with a single CPU.  To run multiple threads
+on a single CPU, then the scheduler must frequently switch between the threads,
+in order that each thread is able to make timely progress.
+This is the basis of any multitasking operating system.
+
+This section explores the differences between the pthread model and the
+L-thread model as implemented in the provided L-thread subsystem. If needed a
+theoretical discussion of preemptive vs cooperative multithreading can be
+found in any good text on operating system design.
+
+Sceduling and context switching
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+The POSIX pthread library provides an application programming interface to
+create and synchronize threads. Scheduling policy is determined by the host OS,
+and may be configurable. The OS may use sophisticated rules to determine which
+thread should be run next, threads may suspend themselves or make other threads
+ready, and the scheduler may employ a time slice giving each thread a maximum
+time quantum after which it will be preempted in favor of another thread that
+is ready to run. To complicate matters further threads may be assigned
+different scheduling priorities.
+
+By contrast the L-thread subsystem is considerably simpler. Logically the
+L-thread scheduler performs the same multiplexing function for L-threads
+within a single pthread as the OS scheduler does for pthreads within an
+application process. The L-thread scheduler is simply the main loop of a
+pthread, and in so far as the host OS is concerned it is just a regular
+pthread like any other.  The host OS is oblivious about the existence of and
+not at all involved in the scheduling of L-threads.
+
+The other and most significant difference between the two models is that
+L-threads are scheduled cooperatively. L-threads cannot not preempt each
+other, nor can the L-thread scheduler preempt a running L-thread ( i.e.
+there is no time slicing). The consequence is that programs implemented with
+L-threads must possess frequent rescheduling points, meaning that they must
+explicitly and of their own volition return to the scheduler at frequent
+intervals, in order to allow other L-threads an opportunity to proceed.
+
+In both models switching between threads requires that the current CPU
+context is saved and a new context (belonging to the next thread ready to run)
+is restored. With pthreads this context switching is handled transparently
+and the set of CPU registers that must be preserved between context switches
+is as per an interrupt handler.
+
+An L-thread context switch is achieved by the thread itself making a function
+call to the L-thread scheduler. Thus it is only necessary to preserve the
+callee registers. The caller is responsible to save and restore any other
+registers it is using before a function call, and restore them on return,
+and this is handled by the compiler. For X86_64 on both Linux and BSD the
+System V calling convention is used, this defines registers RSP,RBP,and R12-R15
+as callee-save registers (for more detailed discussion a good reference
+can be found here https://en.wikipedia.org/wiki/X86_calling_conventions).Taking
+advantage of this, and due to the absence of preemption, an L-thread context
+switch is acheived with less than 20 load/store instructions.
+
+The scheduling policy for L-threads is fixed, there is no prioritization of
+L-threads, all L-threads are equal and scheduling is based on a FIFO
+ready queue.
+
+An L-thread is a struct containing the CPU context of the thread
+(saved on context switch) and other useful items. The ready queue contains
+pointers to threads that are ready to run. The L-thread scheduler is a simple
+loop that polls the ready queue, reads from it the next thread ready to run,
+which it resumes by saving the current context (the current position in the
+scheduler loop) and restoring the context of the next thread from its thread
+struct. Thus an L-thread is always resumed at the last place it yielded.
+
+A well behaved L-thread will call the context switch regularly (at least once
+in its main loop) thus returning to the schedulers own main loop. Yielding
+inserts the current thread at the back of the ready queue, and the process of
+servicing the ready queue is repeated, thus the system runs by flipping back
+and forth the between L-threads and scheduler loop.
+
+In the case of pthreads, the preemptive scheduling, time slicing, and support
+for thread prioritization means that progress is normally possible for any
+thread that is ready to run. This comes at the price of a relatively heavier
+context switch and scheduling overhead.
+
+With L-threads the progress of any particular thread is determined by the
+frequency of rescheduling opportunities in the other L-threads. This means that
+an errant L-thread monopolizing the CPU might cause scheduling of other threads
+to be stalled. Due to the lower cost of context switching, however, voluntary
+rescheduling to ensure progress of other threads, if managed sensibly, is not
+a prohibitive overhead, and overall performance can exceed that of an
+application using pthreads.
+
+Mutual exclusion
+^^^^^^^^^^^^^^^^
+With pthreads preemption means that threads which share data must observe
+some form of mutual exclusion protocol.
+
+The fact that L-threads cannot preempt each other means that mutual exclusion
+devices can be completely avoided.
+
+Locking to protect shared data can be a significant bottleneck in
+multi-threaded applications so a carefully designed cooperatively scheduled
+program can enjoy significant performance advantages.
+
+So far we have considered only the simplistic case of a single core CPU,
+when multiple CPUs are considered things are somewhat more complex.
+
+First of all it is inevitable that there must be multiple L-thread schedulers,
+one on each EAL thread. So long as these schedulers remain isolated from each
+other the above assertions about the potential advantages of cooperative
+scheduling hold true.
+
+A configuration with isolated cooperative schedulers is less flexible than the
+pthread model where threads can be affined to run on any CPU. With isolated
+schedulers scaling of applications to utilize fewer or more CPUs accorindg to
+system demand is very difficult to achieve.
+
+The L-thread subsystem makes it possible for L-threads to migrate between
+schedulers running on different CPUs. Needless to say if the migration means
+that threads that share data end up running on different CPUs then this will
+introduce the need for some kind mutual exclusion device.
+
+Of course rte_ring s/w rings can always be used to interconnect threads running
+on different cores, however to protect other kinds of shared data structures,
+lock free constructs or else explicit locking will be required. This is a
+consideration for the application design.
+
+In support of this extended functionality, the L-thread subsystem implements
+thread safe mutexes and condition variables.
+
+The cost of affining and of condition variable signaling is significantly
+lower than the equivalent pthread operations, and so applications using
+these features will see a performance benefit.
+
+
+Thread local storage
+^^^^^^^^^^^^^^^^^^^^
+
+As with applications written for pthreads an application written for L-threads
+can take advantage of thread local storage, in this case local to an L-thread.
+An application may save and retrieve a single pointer to application data in
+the L-thread struct.
+
+For legacy and backward compatibility reasons two alternative methods are also
+offered, the first is modelled directly on the pthread get/set specific APIs,
+the second approach is modelled on the RTE_PER_LCORE macros, whereby PER_LTHREAD
+macros are introduced, in both cases the storage is local to the L-thread.
+
+
+.. _constraints_and_performance_implications:
+
+Constraints and performance implications when using L-threads
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+.. _API_compatibility:
+
+API compatibility
+^^^^^^^^^^^^^^^^^
+
+The L-thread subsystem provides a set of functions that are logically equivalent
+to the corresponding functions offered by the POSIX pthread library, however not
+all pthread functions have a corresponding L-thread equivalent, and not all
+features available to pthreads are implemented for L-threads.
+
+The pthread library offers considerable flexibility via programmable attributes
+that can be associated with threads, mutexes, and condition variables.
+
+By contrast the L-thread subsystem has fixed functionality, the scheduler policy
+cannot be varied, and L-threads cannot be prioritized. There are no variable
+attributes associated with any L-thread objects. L-threads, mutexs and
+conditional variables, all have fixed functionality. (Note: reserved parameters
+are included in the APIs to facilitate possible future support for attributes).
+
+The table below lists the pthread and equivalent L-thread APIs with notes on
+differences and/or constraints. Where there is no L-thread entry in the table,
+then the L-thread subsystem provides no equivalent function.
+
+.. _table_lthread_pthread:
+
++-----------------------------+-----------------------------+--------------------+
+| **Pthread function**        | **L-thread function**       | **Notes**          |
++=============================+=============================+====================+
+| pthread_barrier_destroy     |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_barrier_init        |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_barrier_wait        |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_cond_broadcast      | lthread_cond_broadcast      | See note 1         |
++-----------------------------+-----------------------------+--------------------+
+| pthread_cond_destroy        | lthread_cond_destroy        |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_cond_init           | lthread_cond_init           |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_cond_signal         | lthread_cond_signal         | See note 1         |
++-----------------------------+-----------------------------+--------------------+
+| pthread_cond_timedwait      |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_cond_wait           | lthread_cond_wait           | See note 5         |
++-----------------------------+-----------------------------+--------------------+
+| pthread_create              | lthread_create              | See notes 2, 3     |
++-----------------------------+-----------------------------+--------------------+
+| pthread_detach              | lthread_detach              | See note 4         |
++-----------------------------+-----------------------------+--------------------+
+| pthread_equal               |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_exit                | lthread_exit                |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_getspecific         | lthread_getspecific         |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_getcpuclockid       |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_join                | lthread_join                |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_key_create          | lthread_key_create          |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_key_delete          | lthread_key_delete          |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_mutex_destroy       | lthread_mutex_destroy       |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_mutex_init          | lthread_mutex_init          |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_mutex_lock          | lthread_mutex_lock          | See note 6         |
++-----------------------------+-----------------------------+--------------------+
+| pthread_mutex_trylock       | lthread_mutex_trylock       | See note 6         |
++-----------------------------+-----------------------------+--------------------+
+| pthread_mutex_timedlock     |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_mutex_unlock        | lthread_mutex_unlock        |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_once                |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_rwlock_destroy      |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_rwlock_init         |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_rwlock_rdlock       |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_rwlock_timedrdlock  |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_rwlock_timedwrlock  |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_rwlock_tryrdlock    |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_rwlock_trywrlock    |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_rwlock_unlock       |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_rwlock_wrlock       |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_self                | lthread_current             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_setspecific         | lthread_setspecific         |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_spin_init           |                             | See note 10        |
++-----------------------------+-----------------------------+--------------------+
+| pthread_spin_destroy        |                             | See note 10        |
++-----------------------------+-----------------------------+--------------------+
+| pthread_spin_lock           |                             | See note 10        |
++-----------------------------+-----------------------------+--------------------+
+| pthread_spin_trylock        |                             | See note 10        |
++-----------------------------+-----------------------------+--------------------+
+| pthread_spin_unlock         |                             | See note 10        |
++-----------------------------+-----------------------------+--------------------+
+| pthread_cancel              | lthread_cancel              |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_setcancelstate      |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_setcanceltype       |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_testcancel          |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_getschedparam       |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_setschedparam       |                             |                    |
++-----------------------------+-----------------------------+--------------------+
+| pthread_yield               | lthread_yield               | See note 7         |
++-----------------------------+-----------------------------+--------------------+
+| pthread_setaffinity_np      | lthread_set_affinity        | See notes 2, 3, 8  |
++-----------------------------+-----------------------------+--------------------+
+|                             | lthread_sleep               | See note 9         |
++-----------------------------+-----------------------------+--------------------+
+|                             | lthread_sleep_clks          | See note 9         |
++-----------------------------+-----------------------------+--------------------+
+
+
+Note 1:
+
+neither lthread_signal nor broadcast may be called concurrently by L-threads
+running on different schedulers, although multiple L-threads running in the
+same scheduler may freely perform signal or broadcast operations. L-threads
+running on the same or different schedulers may always safely wait on a condition
+variable.
+
+
+Note 2:
+
+pthread attributes may be used to affine a pthread with a cpu-set. The L-thread
+subsystem does not support a cpu-set. An L-thread may be affined only with a
+single CPU at any time.
+
+
+Note 3:
+
+if an L-thread is intended to run on a different NUMA node than the node that
+creates it then, when calling lthread_create() it is advantageous to specify
+the destination core as a parameter of lthread_create()
+See :ref:`memory_allocation_and_NUMA_awareness` for details.
+
+
+Note 4:
+
+an L-thread can only detach itself, and cannot detach other L-threads.
+
+
+Note 5:
+
+a wait operation on a pthread condition variable is always associated with and
+protected by a mutex which must be owned by the thread at the time it invokes
+pthread_wait(). By contrast L-thread condition variables are thread safe
+(for waiters) and do not use an associated mutex. Multiple L-threads (including
+L-threads running on other schedulers) can safely wait on a L-thread condition
+variable. As a consequence the performance of an L-thread condition variable is
+typically an order of magnitude faster than its pthread counterpart.
+
+
+Note 6:
+
+recursive locking is not supported with L-threads, attempts to take a lock
+recursively will be detected and rejected.
+
+
+Note 7:
+
+lthread_yield() will save the current context, insert the current thread to the
+back of the ready queue, and resume the next ready thread. Yielding increases
+ready queue backlog, see :ref:`ready_queue_backlog` for more details about the
+implications of this.
+
+
+N.B. The context switch time as measured from immediately before the call to
+lthread_yield() to the point at which the next ready thread is resumed, can be
+an order of magnitude faster that the same measurement for pthread_yield.
+
+
+Note 8:
+
+lthread_set_affinity() is similar to a yield apart from the fact that the
+yielding thread is inserted into a peer ready queue of another scheduler.
+The peer ready queue is actually a separate thread safe queue, which means that
+threads appearing in the peer ready queue can jump any backlog in the local
+ready queue on the destination scheduler.
+
+The context switch time as measured from the time just before the call to
+lthread_set_affinity() to just after the same thread is resumed on the new
+scheduler can be orders of magnitude faster than the same measurement for
+pthread_setaffinity_np().
+
+
+Note 9:
+
+although there is no pthread_sleep() function, lthread_sleep() and
+lthread_sleep_clks() can be used wherever sleep(), usleep() or  nanosleep()
+might ordinarily be used. The L-thread sleep functions suspend the current
+thread, start an rte_timer and resume the thread when the timer matures.
+The rte_timer_manage() entry point is called on every pass of the scheduler
+loop. This means that the worst case jitter on timer expiry is determined by
+the longest period between context switches of any running L-threads.
+
+In a synthetic test with many threads sleeping and resuming then the measured
+jitter is typically orders of magnitude lower than the same measurement made
+for nanosleep().
+
+
+Note 10:
+
+spin locks are not provided because they are problematical in a cooperative
+environment, see :ref:`porting_locks_and_spinlocks` for a more detailed
+discussion on how to avoid spin locks.
+
+.. _Thread_local_storage_performance:
+
+Thread local storage
+^^^^^^^^^^^^^^^^^^^^
+
+Of the three L-thread local storage options the simplest and most efficient is
+storing a single application data pointer in the L-thread struct.
+
+The PER_LTHREAD macros involve a run time computation to obtain the address
+of the variable being saved/retrieved and also require that the accesses are
+de-referenced  via a pointer. This means that code that has used
+RTE_PER_LCORE macros being ported to L-threads might need some slight
+adjustment (see :ref:`porting_thread_local_storage` for hints about porting
+code that makes use of thread local storage).
+
+The get/set specific APIs are consistent with their pthread counterparts both
+in use and in performance.
+
+.. _memory_allocation_and_NUMA_awareness:
+
+Memory allocation and NUMA awareness
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+All memory allocation is from DPDK huge pages, and is NUMA aware. Each
+scheduler maintains its own caches of objects: lthreads, their stacks, TLS,
+mutexes and condition variables. These caches are implemented as unbounded lock
+free MPSC queues.  When objects are created they are always allocated from the
+caches on the local core (current EAL thread).
+
+If an L-thread has affined to a different sheduler, then it can always safely
+free resources to the caches from which they originated (because the caches are
+MPSC queues).
+
+If the L-thread has affined to a different NUMA node then the memory resources
+associated with it may incur longer access latency.
+
+The commonly used pattern of setting affinity on entry to a thread after it has
+started, means that memory allocation for both the stack and TLS will have been
+made from caches on the NUMA node on which the threads creator is running.
+This has the side effect that access latency will be sub-optimal after
+affining.
+
+This side effect can be mitigated to some extent (although not completely) by
+specifying the destination CPU as a parameter of lthread_create() this causes
+the L-thread’s stack and TLS to be allocated when it is first scheduled on the
+destination scheduler, if the destination is a on another NUMA node it results
+in a more optimal memory allocation.
+
+Note that the lthread struct itself remains allocated from memory on the node
+creating node, this is unavoidable because an L-thread is known everywhere by
+the address of this struct.
+
+.. _object_cache_sizing:
+
+Object cache sizing
+^^^^^^^^^^^^^^^^^^^
+
+The per lcore object caches pre-allocate objects in bulk whenever a request to
+allocate an object finds a cache empty.  By default 100 objects are
+pre-allocated, this is defined by LTHREAD_PREALLOC in the public API header
+file lthread_api.h. This means that the caches constantly grow to meet system
+demand.
+
+In the present implementation there is no mechanism to reduce the cache sizes
+if system demand reduces. Thus the caches will remain at their maximum extent
+indefinitely.
+
+A consequence of the bulk pre-allocation of objects is that every 100
+(default value) additional new object create operations results in a call to
+rte_malloc. For creation of objects such as L-threads, which trigger the
+allocation of even more objects ( i.e. their stacks and TLS) then this can
+cause outliers in scheduling performance.
+
+If this is a problem the simplest mitigation strategy is to dimension the
+system, by setting the bulk object pre-allocation size to some large number
+that you do not expect to be exceeded. This means the caches will be populated
+once only, the very first time a thread is created.
+
+.. _Ready_queue_backlog:
+
+Ready queue backlog
+^^^^^^^^^^^^^^^^^^^
+
+One of the more subtle performance considerations is managing the ready queue
+backlog. The fewer threads that are waiting in the ready queue then the faster
+any particular thread will get serviced.
+
+In a naive L-thread application with N L-threads simply looping and yielding,
+this backlog will always be equal to the number of L-threads, thus the cost of
+a yield to a particular L-thread will be N times the context switch time.
+
+This side effect can be mitigated by arranging for threads to be suspended and
+waiting to be resumed, rather than polling for work by constantly yielding.
+Blocking on a mutex or condition variable or even more obviously having a
+thread sleep if it has a low frequency workload are all mechanisms by which a
+thread can be excluded from the ready queue until it really does need to be
+running.  This can have a significant positive impact on performance.
+
+.. _Initialization_and_shutdown_dependencies:
+
+Initialization, shutdown and dependencies
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The L-thread subsystem depends on DPDK for huge page allocation and depends on
+the rte_timer subsystem. The DPDK EAL initialization and
+rte_timer_subsystem_init()  MUST be completed before the L-thread sub system
+can be used.
+
+Thereafter initialization of the L-thread subsystem is largely transparent to
+the application. Constructor functions ensure that global variables are properly
+initialized. Other than global variables each scheduler is initialized
+independently the first time that an L-thread is created by a particular EAL
+thread.
+
+If the schedulers are to be run as isolated and independent schedulers, with
+no intention that L-threads running on different schedulers will migrate between
+schedulers or synchronize with L-threads running on other schedulers, then
+initialization consists simply of creating an L-thread, and then running the
+L-thread scheduler.
+
+If there will be interaction between L-threads running on different schedulers,
+then it is important that the starting of schedulers on different EAL threads
+is synchronized.
+
+To achieve this an additional initialization step is necessary, this is simply
+to set the number of schedulers by calling the API function
+lthread_num_schedulers_set(n), where n = the number of EAL threads that will
+run L-thread schedulers. Setting the number of schedulers to a number greater
+than 0 will cause all schedulers to wait until the others have started before
+beginning to schedule L-threads.
+
+The L-thread scheduler is started by calling the function
+lthread_scheduler_run() and should be called from the EAL thread and thus
+become the main loop of the EAL thread.
+
+The function lthread_scheduler run(), will not return until all threads running
+on the scheduler have exited, and the scheduler has been explicitly stopped by
+calling lthread_scheduler_shutdown(lcore) or lthread_scheduler_shutdown_all().
+
+All these function do is tell the scheduler that it can exit when there are no
+longer any running L-threads, neither function forces any running L-thread to
+terminate.  Any desired application shutdown behavior must be designed and
+built into the application to ensure that L-threads complete in a timely
+manner.
+
+**Important Note:** It is assumed when the scheduler exits that the application
+is terminating for good, the scheduler does not free resources before exiting
+and running the scheduler a subsequent time will result in undefined behavior.
+
+.. _porting_legacy_code_to_run_on_lthreads:
+
+Porting legacy code to run on L-threads
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Legacy code originally written for a pthread environment may be ported to
+L-threads if the considerations about differences in scheduling policy, and
+constraints discussed in the previous sections can be accommodated.
+
+This section looks in more detail at some of the issues that may have to be
+resolved when porting code.
+
+.. _pthread_API_compatibility:
+
+pthread API compatibility
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The first step is to establish exactly which pthread APIs the legacy
+application uses, and to understand the requirements of those APIs.  If there
+are corresponding L-lthread APIs, and where the default pthread functionality
+is used by the application then, notwithstanding the other issues discussed
+here, it should be feasible to run the application with L-threads. If the
+legacy code modifies the default behavior using attributes then if may be
+necessary to make some adjustments to eliminate those requirements.
+
+.. _blocking_system_calls:
+
+Blocking system API calls
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+It is important to understand what other system services the application may be
+using, bearing in mind that in a cooperatively scheduled environment a thread
+cannot block without stalling the scheduler and with it all other cooperative
+threads. Any kind of blocking system call, for example file or socket IO, is a
+potential problem, a good tool to analyze the application for this purpose is
+the “strace” utility.
+
+There are many strategies to resolve these kind of issues, each with it
+merits. Possible solutions include:-
+
+Adopting a polled mode of the system API concerned (if available).
+
+Arranging for another core to perform the function and synchronizing with that
+core via constructs that will not block the L-thread.
+
+Affining the thread to another scheduler devoted (as a matter of policy) to
+handling threads wishing to make blocking calls, and then back again when
+finished.
+
+
+.. _porting_locks_and_spinlocks:
+
+Locks and spinlocks
+^^^^^^^^^^^^^^^^^^^
+
+Locks and spinlocks are another source of blocking behavior that for the same
+reasons as system calls will need to be addressed.
+
+If the application design ensures that the contending L-threads will always
+run on the same scheduler then it its probably safe to remove locks and spin
+locks completely, the only exception to this rule is if for some reason the
+code performs any kind of context switch whilst holding the lock, this will
+need to determined before deciding to eliminate a lock.
+
+If a lock cannot be eliminated then an L-thread mutex can be substituted for
+either kind of lock.
+
+An L-thread blocking on an L-thread mutex will be suspended and will cause
+another ready L-thread to be resumed, thus not blocking the scheduler. When
+default behaviour is required, it can be used as a direct replacement for a
+pthread mutex lock.
+
+Spin locks are typically used when lock contention is likely to be rare and
+where the period during which the lock is held is relatively short.  When the
+contending L-threads are running on the same scheduler then an L-thread
+blocking on a spin lock will enter an infinite loop stopping the scheduler
+completely (see :ref:`porting_infinite_loops` below ).
+
+If the application design ensures that contending L-threads will always run
+on different schedulers then it might be reasonable to leave a short spin lock
+that rarely experiences contention in place.
+
+If after all considerations it appears that a spin lock can neither be
+eliminated completely, replaced with an L-thread mutex, or left in place as
+is, then an alternative is to loop on a flag, with a call to lthread_yield()
+inside the loop ( n.b. if the contending L-threads might ever run on different
+schedulers the flag will need to be manipulated atomically ).
+
+Spinning and yielding is the least preferred solution since it introduces
+ready queue backlog ( see also :ref:`ready_queue_backlog`).
+
+.. _porting_sleeps_and_delays:
+
+Sleeps and delays
+^^^^^^^^^^^^^^^^^
+
+Yet another kind of blocking behavior (albeit momentary) are delay functions
+like sleep(), usleep(), nanosleep() etc. All will have the consequence of
+stalling the L-thread scheduler and unless the delay is very short ( e.g. a
+very short nanosleep) calls to these functions will need to be eliminated.
+
+The simplest mitigation strategy is to use the L-thread sleep API functions,
+of which two variants exist, lthread_sleep()  and lthread_sleep_clks().
+These functions start an rte_timer against the L-thread, suspend the L-thread
+and cause another ready L-thread to be resumed. The suspended L-thread is
+resumed when the rte_timer matures.
+
+.. _porting_infinite_loops:
+
+Infinite loops
+^^^^^^^^^^^^^^
+
+Some applications have threads with loops that contain no inherent
+rescheduling opportunity, and rely solely on the OS time slicing to share
+the CPU.  In a cooperative environment this will stop everything dead. These
+kind of loops are not hard to identify, in a debug session you will find the
+debugger is always stopping in the same loop.
+
+The simplest solution to this kind of problem is to insert an explicit
+lthread_yield() or lthread_sleep()  into the loop. Another solution might be
+to include the function performed by the loop into the execution path of some
+other loop that does in fact yield, if this is possible.
+
+.. _porting_thread_local_storage:
+
+Thread local storage
+^^^^^^^^^^^^^^^^^^^^
+
+If the application uses thread local storage, the use case should be
+studied carefully.
+
+In a legacy pthread application either or both the __thread  prefix, or the
+pthread set/get specific APIs may have been used to define storage local
+to a pthread.
+
+In some applications it may be a reasonable assumption that the data could
+or in fact most likely should be placed in L-thread local storage.
+
+If the application (like many DPDK applications) has assumed a certain
+relationship between a pthread and the CPU to which it is affined, there is
+a risk that thread local storage may have been used to save some data items
+that are correctly logically associated with the CPU, and others items which
+relate to application context for the thread.  Only a good understanding of
+the application will reveal such cases.
+
+If the application requires an that an L-thread is to be able to move between
+schedulers then care should be taken to separate these kinds of data, into per
+lcore, and per L-thread storage. In this way a migrating thread will bring with
+it the local data it needs, and pick up the new logical core specific values
+from pthread local storage at its new home.
+
+.. _pthread_shim:
+
+Pthread shim
+~~~~~~~~~~~~
+
+A convenient way to get something working with legacy code can be to use a
+shim that adapts pthread API calls to the corresponding L-thread ones.
+This approach will not mitigate any of the porting considerations mentioned
+in the previous sections, but it will reduce the amount of code churn that
+would otherwise been involved. It is a reasonable approach to evaluate
+L-threads, before investing effort in porting to the native L-thread APIs.
+
+Overview
+^^^^^^^^
+The L-thread subsystem includes an example pthread shim. This is a partial
+implementation but does contain the API stubs needed to get basic applications
+running.  There is a simple “hello world” application that demonstrates the
+use of the pthread shim.
+
+A subtlety of working with a shim is that the application will still need
+to make use of the genuine pthread library functions, at the very least in
+order to create the EAL threads in which the L-thread schedulers will run.
+This is the case with DPDK initialization, and exit.
+
+To deal with the initialization and shutdown scenarios, the shim is capable
+of switching on or off its adaptor functionality, an application can control
+this behavior by the calling the function pt_override_set(). The default state
+is disabled.
+
+(Note: bearing in mind the preceding discussions about the impact of making
+blocking system API calls in a cooperative environment, then switching the
+shim in and out on the fly is something that should typically be avoided.)
+
+The pthread shim uses the dynamic linker loader and saves the loaded addresses
+of the genuine pthread API functions in an internal table, when the shim
+functionality is enabled it performs the adaptor function, when disabled it
+invokes the genuine pthread function.
+
+The function pthread_exit() has additional special handling. The standard
+system header file pthread.h declares pthread_exit()
+with __attribute__((noreturn))  this is an optimization that is possible
+because the pthread is terminating and this enables the compiler to omit the
+normal handling of stack and protection of registers since the function is not
+expected to return, and in fact the thread is being destroyed.
+These optimizations are applied in both the callee and the caller of the
+pthread_exit() function.
+
+In our cooperative scheduling environment this behavior is inadmissible.
+The pthread is the L-thread scheduler thread, and, although an L-thread is
+terminating, there must be a return to the scheduler in order that system can
+continue to run. Further, returning from a function with attribute noreturn is
+invalid and may result in undefined behavior.
+
+The solution is to redefine the pthread_exit function with a macro, causing it
+to be mapped to a stub function in the shim that does not have the (noreturn)
+attribute.  This macro is defined in the file pthread_shim.h. The stub function
+is otherwise no different than any of the other stub functions in the shim,
+and will switch between the real pthread_exit() function or the lthread_exit()
+function as required. The only difference is that the mapping to the stub by
+macro substitution.
+
+A consequence of this is that the file pthread_shim.h must be included in
+legacy code wishing to make use of the shim. It also means that dynamic linkage
+of a pre-compiled binary that did not include pthread_shim.h is not be supported.
+
+Given the requirements for porting legacy code outlined in
+:ref:`porting_legacy_code_to_run_on_lthreads` most applications will require at
+least some minimal adjustment and recompilation to run on L-threads so
+pre-compiled binaries are unlikely to be met in practice.
+
+In summary the shim approach adds some overhead but can be a useful tool to help
+establish the feasibility of a code reuse project. It is also a fairly
+straightforward task to extend the shim if necessary.
+
+**Note:** Bearing in mind the preceding discussions about the impact of making
+blocking calls then switching the shim in and out on the fly to invoke any
+pthread API this might block is something that should typically be avoided.
+
+
+Building and running the pthread shim
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The shim example application is located in the sample application
+in the performance-thread folder
+
+To build and run the pthread shim example
+
+#.   Go to the example applications folder
+
+    .. code-block:: console
+
+	export RTE_SDK=/path/to/rte_sdk cd ${RTE_SDK}/examples/performance-thread/pthread_shim
+
+
+#.   Set the target (a default target is used if not specified). For example:
+
+    .. code-block:: console
+
+	export RTE_TARGET=x86_64-native-linuxapp-gcc
+
+	See the DPDK Getting Started Guide for possible RTE_TARGET values.
+
+#.   Build the application:
+
+    .. code-block:: console
+
+	make
+
+#.   To run the pthread_shim example
+
+    .. code-block:: console
+
+	lthread-pthread-shim –c < core mask ) –n <number of channels >
+
+.. _lthread_diagnostics:
+
+L-thread Diagnostics
+~~~~~~~~~~~~~~~~~~~~
+
+When debugging you must take account of the fact that the L-threads are run in
+a single pthread. The current scheduler is defined by
+RTE_PER_LCORE(this_sched), and the current lthread is stored at
+RTE_PER_LCORE(this_sched)->current_lthread.
+Thus on a breakpoint in a GDB session the current lthread can be obtained by
+displaying the pthread local variable  "per_lcore_this_sched->current_lthread".
+
+Another useful diagnostic feature is the possibility to trace significant
+events in the life of an L-thread, this feature is enabled by changing the
+value of LTHREAD_DIAG from 0 to 1 in the file lthread_diag_api.h.
+
+Tracing of events can be individually masked, and the mask may be programmed at
+run time.
+An unmasked event results in a callback that provides information
+about the event. The default callback simply prints trace information.
+The default mask is 0 (all events off) the mask can be modified by calling the
+function lthread_diagniostic_set_mask().
+
+It is possible register a user callback to implement more sophisticated
+diagnostic functions.
+Object creation events (lthread, mutex, and condition variable) accept, and
+store in the created object, a user supplied reference value from the callback
+function.
+
+The reference value is passed back in all subsequent event callbacks pertaining
+to the object, enabling a user to monitor, count, or even monitor specific
+vents, on specific objects, for example to monitor for a specific thread
+signalling a specific condition variable, or to monitor on all timer events,
+the possibilities and combinations are endless.
+
+The callback can be set by calling the function lthread_diagnostic_enable()
+supplying a callback and an event mask.
+
+Setting LTHREAD_DIAG also enables counting of statistics about cache and
+queue usage, and these statistics can be displayed by calling the function
+lthread_diag_stats_display(). This function also performs a consistency check
+on the caches and queues. The function should only be called from the master
+EAL thread after all slave threads have stopped and returned to the C main
+program, otherwise the consistency check will fail.
-- 
1.9.3