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_dir>/examples/dpdk-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
~~~~~~~~~~~~~~~~~~~~~~~~~~~
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