-.. BSD LICENSE
- Copyright(c) 2017 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,
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- LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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- 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) 2017 Intel Corporation.
.. _Metrics_Library:
restriction on port numbers is that they are less than ``RTE_MAX_ETHPORTS``
- there is no requirement for the ports to actually exist.
-Initialising the library
+Initializing the library
------------------------
Before the library can be used, it has to be initialized by calling
.. code-block:: c
void print_metrics() {
+ struct rte_metric_value *metrics;
struct rte_metric_name *names;
int len;
free(metrics);
free(names);
}
+
+
+Deinitialising the library
+--------------------------
+
+Once the library usage is done, it must be deinitialized by calling
+``rte_metrics_deinit()`` which will free the shared memory reserved
+during initialization.
+
+.. code-block:: c
+
+ err = rte_metrics_deinit(void);
+
+If the return value is negative, it means deinitialization failed.
+This function **must** be called from a primary process.
+
+Bit-rate statistics library
+---------------------------
+
+The bit-rate library calculates the exponentially-weighted moving
+average and peak bit-rates for each active port (i.e. network device).
+These statistics are reported via the metrics library using the
+following names:
+
+ - ``mean_bits_in``: Average inbound bit-rate
+ - ``mean_bits_out``: Average outbound bit-rate
+ - ``ewma_bits_in``: Average inbound bit-rate (EWMA smoothed)
+ - ``ewma_bits_out``: Average outbound bit-rate (EWMA smoothed)
+ - ``peak_bits_in``: Peak inbound bit-rate
+ - ``peak_bits_out``: Peak outbound bit-rate
+
+Once initialised and clocked at the appropriate frequency, these
+statistics can be obtained by querying the metrics library.
+
+Initialization
+~~~~~~~~~~~~~~
+
+Before the library can be used, it has to be initialised by calling
+``rte_stats_bitrate_create()``, which will return a bit-rate
+calculation object. Since the bit-rate library uses the metrics library
+to report the calculated statistics, the bit-rate library then needs to
+register the calculated statistics with the metrics library. This is
+done using the helper function ``rte_stats_bitrate_reg()``.
+
+.. code-block:: c
+
+ struct rte_stats_bitrates *bitrate_data;
+
+ bitrate_data = rte_stats_bitrate_create();
+ if (bitrate_data == NULL)
+ rte_exit(EXIT_FAILURE, "Could not allocate bit-rate data.\n");
+ rte_stats_bitrate_reg(bitrate_data);
+
+Controlling the sampling rate
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Since the library works by periodic sampling but does not use an
+internal thread, the application has to periodically call
+``rte_stats_bitrate_calc()``. The frequency at which this function
+is called should be the intended sampling rate required for the
+calculated statistics. For instance if per-second statistics are
+desired, this function should be called once a second.
+
+.. code-block:: c
+
+ tics_datum = rte_rdtsc();
+ tics_per_1sec = rte_get_timer_hz();
+
+ while( 1 ) {
+ /* ... */
+ tics_current = rte_rdtsc();
+ if (tics_current - tics_datum >= tics_per_1sec) {
+ /* Periodic bitrate calculation */
+ for (idx_port = 0; idx_port < cnt_ports; idx_port++)
+ rte_stats_bitrate_calc(bitrate_data, idx_port);
+ tics_datum = tics_current;
+ }
+ /* ... */
+ }
+
+
+Latency statistics library
+--------------------------
+
+The latency statistics library calculates the latency of packet
+processing by a DPDK application, reporting the minimum, average,
+and maximum nano-seconds that packet processing takes, as well as
+the jitter in processing delay. These statistics are then reported
+via the metrics library using the following names:
+
+ - ``min_latency_ns``: Minimum processing latency (nano-seconds)
+ - ``avg_latency_ns``: Average processing latency (nano-seconds)
+ - ``mac_latency_ns``: Maximum processing latency (nano-seconds)
+ - ``jitter_ns``: Variance in processing latency (nano-seconds)
+
+Once initialised and clocked at the appropriate frequency, these
+statistics can be obtained by querying the metrics library.
+
+Initialization
+~~~~~~~~~~~~~~
+
+Before the library can be used, it has to be initialised by calling
+``rte_latencystats_init()``.
+
+.. code-block:: c
+
+ lcoreid_t latencystats_lcore_id = -1;
+
+ int ret = rte_latencystats_init(1, NULL);
+ if (ret)
+ rte_exit(EXIT_FAILURE, "Could not allocate latency data.\n");
+
+
+Triggering statistic updates
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``rte_latencystats_update()`` function needs to be called
+periodically so that latency statistics can be updated.
+
+.. code-block:: c
+
+ if (latencystats_lcore_id == rte_lcore_id())
+ rte_latencystats_update();
+
+Library shutdown
+~~~~~~~~~~~~~~~~
+
+When finished, ``rte_latencystats_uninit()`` needs to be called to
+de-initialise the latency library.
+
+.. code-block:: c
+
+ rte_latencystats_uninit();
+
+Timestamp and latency calculation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The Latency stats library marks the time in the timestamp field of the
+mbuf for the ingress packets and sets the ``PKT_RX_TIMESTAMP`` flag of
+``ol_flags`` for the mbuf to indicate the marked time as a valid one.
+At the egress, the mbufs with the flag set are considered having valid
+timestamp and are used for the latency calculation.
git.droids-corp.org / dpdk.git / blobdiff