This application includes a P-state power management algorithm to generate a frequency hint to be sent to CPUFreq.
The algorithm uses the number of received and available Rx packets on recent polls to make a heuristic decision to scale frequency up/down.
-Specifically, some thresholds are checked to see whether a specific core running an DPDK polling thread needs to increase frequency
+Specifically, some thresholds are checked to see whether a specific core running a DPDK polling thread needs to increase frequency
a step up based on the near to full trend of polled Rx queues.
Also, it decreases frequency a step if packet processed per loop is far less than the expected threshold
or the thread's sleeping time exceeds a threshold.
.. code-block:: console
- ./build/l3fwd_power [EAL options] -- -p PORTMASK [-P] --config(port,queue,lcore)[,(port,queue,lcore)] [--enable-jumbo [--max-pkt-len PKTLEN]] [--no-numa]
+ ./<build_dir>/examples/dpdk-l3fwd_power [EAL options] -- -p PORTMASK [-P] --config(port,queue,lcore)[,(port,queue,lcore)] [--max-pkt-len PKTLEN] [--no-numa]
where,
* --config (port,queue,lcore)[,(port,queue,lcore)]: determines which queues from which ports are mapped to which cores.
-* --enable-jumbo: optional, enables jumbo frames
-
* --max-pkt-len: optional, maximum packet length in decimal (64-9600)
* --no-numa: optional, disables numa awareness
* --telemetry: Telemetry mode.
+* --pmd-mgmt: PMD power management mode.
+
See :doc:`l3_forward` for details.
The L3fwd-power example reuses the L3fwd command line options.
Only the power management related initialization is shown.
-.. code-block:: c
-
- int main(int argc, char **argv)
- {
- struct lcore_conf *qconf;
- int ret;
- unsigned nb_ports;
- uint16_t queueid, portid;
- unsigned lcore_id;
- uint64_t hz;
- uint32_t n_tx_queue, nb_lcores;
- uint8_t nb_rx_queue, queue, socketid;
-
- // ...
-
- /* init RTE timer library to be used to initialize per-core timers */
-
- rte_timer_subsystem_init();
-
- // ...
-
-
- /* per-core initialization */
-
- for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
- if (rte_lcore_is_enabled(lcore_id) == 0)
- continue;
-
- /* init power management library for a specified core */
-
- ret = rte_power_init(lcore_id);
- if (ret)
- rte_exit(EXIT_FAILURE, "Power management library "
- "initialization failed on core%d\n", lcore_id);
-
- /* init timer structures for each enabled lcore */
-
- rte_timer_init(&power_timers[lcore_id]);
-
- hz = rte_get_hpet_hz();
-
- rte_timer_reset(&power_timers[lcore_id], hz/TIMER_NUMBER_PER_SECOND, SINGLE, lcore_id, power_timer_cb, NULL);
-
- // ...
- }
-
- // ...
- }
+.. literalinclude:: ../../../examples/l3fwd-power/main.c
+ :language: c
+ :start-after: Power library initialized in the main routine. 8<
+ :end-before: >8 End of power library initialization.
Monitoring Loads of Rx Queues
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Only power control related code is shown.
-.. code-block:: c
-
- static
- __rte_noreturn int main_loop(__rte_unused void *dummy)
- {
- // ...
-
- while (1) {
- // ...
-
- /**
- * Read packet from RX queues
- */
-
- lcore_scaleup_hint = FREQ_CURRENT;
- lcore_rx_idle_count = 0;
-
- for (i = 0; i < qconf->n_rx_queue; ++i)
- {
- rx_queue = &(qconf->rx_queue_list[i]);
- rx_queue->idle_hint = 0;
- portid = rx_queue->port_id;
- queueid = rx_queue->queue_id;
-
- nb_rx = rte_eth_rx_burst(portid, queueid, pkts_burst, MAX_PKT_BURST);
- stats[lcore_id].nb_rx_processed += nb_rx;
-
- if (unlikely(nb_rx == 0)) {
- /**
- * no packet received from rx queue, try to
- * sleep for a while forcing CPU enter deeper
- * C states.
- */
-
- rx_queue->zero_rx_packet_count++;
-
- if (rx_queue->zero_rx_packet_count <= MIN_ZERO_POLL_COUNT)
- continue;
-
- rx_queue->idle_hint = power_idle_heuristic(rx_queue->zero_rx_packet_count);
- lcore_rx_idle_count++;
- } else {
- rx_ring_length = rte_eth_rx_queue_count(portid, queueid);
-
- rx_queue->zero_rx_packet_count = 0;
-
- /**
- * do not scale up frequency immediately as
- * user to kernel space communication is costly
- * which might impact packet I/O for received
- * packets.
- */
-
- rx_queue->freq_up_hint = power_freq_scaleup_heuristic(lcore_id, rx_ring_length);
- }
-
- /* Prefetch and forward packets */
-
- // ...
- }
-
- if (likely(lcore_rx_idle_count != qconf->n_rx_queue)) {
- for (i = 1, lcore_scaleup_hint = qconf->rx_queue_list[0].freq_up_hint; i < qconf->n_rx_queue; ++i) {
- x_queue = &(qconf->rx_queue_list[i]);
-
- if (rx_queue->freq_up_hint > lcore_scaleup_hint)
-
- lcore_scaleup_hint = rx_queue->freq_up_hint;
- }
-
- if (lcore_scaleup_hint == FREQ_HIGHEST)
-
- rte_power_freq_max(lcore_id);
-
- else if (lcore_scaleup_hint == FREQ_HIGHER)
- rte_power_freq_up(lcore_id);
- } else {
- /**
- * All Rx queues empty in recent consecutive polls,
- * sleep in a conservative manner, meaning sleep as
- * less as possible.
- */
-
- for (i = 1, lcore_idle_hint = qconf->rx_queue_list[0].idle_hint; i < qconf->n_rx_queue; ++i) {
- rx_queue = &(qconf->rx_queue_list[i]);
- if (rx_queue->idle_hint < lcore_idle_hint)
- lcore_idle_hint = rx_queue->idle_hint;
- }
-
- if ( lcore_idle_hint < SLEEP_GEAR1_THRESHOLD)
- /**
- * execute "pause" instruction to avoid context
- * switch for short sleep.
- */
- rte_delay_us(lcore_idle_hint);
- else
- /* long sleep force ruining thread to suspend */
- usleep(lcore_idle_hint);
-
- stats[lcore_id].sleep_time += lcore_idle_hint;
- }
- }
- }
+.. literalinclude:: ../../../examples/l3fwd-power/main.c
+ :language: c
+ :start-after: Main processing loop. 8<
+ :end-before: >8 End of main processing loop.
P-State Heuristic Algorithm
~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: console
- ./l3fwd-power -l xxx -n 4 -w 0000:xx:00.0 -w 0000:xx:00.1 -- -p 0x3 -P --config="(0,0,xx),(1,0,xx)" --empty-poll="0,0,0" -l 14 -m 9 -h 1
+ ./<build_dir>/examples/dpdk-l3fwd-power -l xxx -n 4 -a 0000:xx:00.0 -a 0000:xx:00.1 \
+ -- -p 0x3 -P --config="(0,0,xx),(1,0,xx)" --empty-poll="0,0,0" -l 14 -m 9 -h 1
Where,
.. code-block:: console
- ./examples/l3fwd-power/build/l3fwd-power -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" --empty-poll "1,0,0" –P
+ ./<build_dir>/examples/dpdk-l3fwd-power -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" --empty-poll "1,0,0" –P
This will run the training algorithm for x seconds on each core (cores 2
and 3), and then print out the recommended threshold values for those
.. code-block:: console
- ./examples/l3fwd-power/build/l3fwd-power -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" --empty-poll "0,340000,540000" –P
+ ./<build_dir>/examples/dpdk-l3fwd-power -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" --empty-poll "0,340000,540000" –P
Telemetry Mode
--------------
``l3fwd-power`` does simple l3fwding along with calculating empty polls, full polls,
and busy percentage for each forwarding core. The aggregation of these
values of all cores is reported as application level telemetry to metric
-library for every 500ms from the master core.
+library for every 500ms from the main core.
The busy percentage is calculated by recording the poll_count
and when the count reaches a defined value the total
reference cycles and accordingly busy rate is set to either 0% or
50% or 100%.
- .. Note::
-
- * The CONFIG_RTE_LIBRTE_TELEMETRY should be set in order to get the stats in DPDK telemetry.
-
.. code-block:: console
- ./examples/l3fwd-power/build/l3fwd-power --telemetry -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" --telemetry
+ ./<build_dir>/examples/dpdk-l3fwd-power --telemetry -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" --telemetry
The new stats ``empty_poll`` , ``full_poll`` and ``busy_percent`` can be viewed by running the script
``/usertools/dpdk-telemetry-client.py`` and selecting the menu option ``Send for global Metrics``.
+
+PMD power management Mode
+-------------------------
+
+The PMD power management mode support for ``l3fwd-power`` is a standalone mode.
+In this mode, ``l3fwd-power`` does simple l3fwding
+along with enabling the power saving scheme on specific port/queue/lcore.
+Main purpose for this mode is to demonstrate
+how to use the PMD power management API.
+
+.. code-block:: console
+
+ ./build/examples/dpdk-l3fwd-power -l 1-3 -- --pmd-mgmt -p 0x0f --config="(0,0,2),(0,1,3)"
+
+PMD Power Management Mode
+-------------------------
+
+There is also a traffic-aware operating mode that,
+instead of using explicit power management,
+will use automatic PMD power management.
+This mode is limited to one queue per core,
+and has three available power management schemes:
+
+``monitor``
+ This will use ``rte_power_monitor()`` function to enter
+ a power-optimized state (subject to platform support).
+
+``pause``
+ This will use ``rte_power_pause()`` or ``rte_pause()``
+ to avoid busy looping when there is no traffic.
+
+``scale``
+ This will use frequency scaling routines
+ available in the ``librte_power`` library.
+
+See :doc:`Power Management<../prog_guide/power_man>` chapter
+in the DPDK Programmer's Guide for more details on PMD power management.
+
+.. code-block:: console
+
+ ./<build_dir>/examples/dpdk-l3fwd-power -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" --pmd-mgmt=scale
git.droids-corp.org / dpdk.git / blobdiff