110 lines
3.2 KiB
ReStructuredText
110 lines
3.2 KiB
ReStructuredText
.. _8021Qav:
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IEEE 802.1Qav
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#############
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Overview
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********
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Credit-based shaping is an alternative scheduling algorithm used in
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network schedulers to achieve fairness when sharing a limited network
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resource. Zephyr has support for configuring a credit-based shaper
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described in the `IEEE 802.1Qav-2009 standard`_. Zephyr does not
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implement the actual shaper; it only provides a way to configure the
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shaper implemented by the Ethernet device driver.
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Enabling 802.1Qav
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*****************
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To enable 802.1Qav shaper, the Ethernet device driver must declare
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that it supports credit-based shaping. The Ethernet driver's capability
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function must return ``ETHERNET_QAV`` value for this purpose. Typically
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also priority queues ``ETHERNET_PRIORITY_QUEUES`` need to be supported.
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.. code-block:: none
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static enum ethernet_hw_caps eth_get_capabilities(struct device *dev)
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{
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ARG_UNUSED(dev);
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return ETHERNET_QAV | ETHERNET_PRIORITY_QUEUES |
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ETHERNET_HW_VLAN | ETHERNET_LINK_10BASE_T |
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ETHERNET_LINK_100BASE_T;
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}
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See ``sam-e70-xplained`` board Ethernet driver
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:zephyr_file:`drivers/ethernet/eth_sam_gmac.c` for an example.
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Configuring 802.1Qav
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********************
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The application can configure the credit-based shaper like this:
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.. code-block:: c
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#include <net/net_if.h>
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#include <net/ethernet.h>
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#include <net/ethernet_mgmt.h>
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static void qav_set_status(struct net_if *iface,
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int queue_id, bool enable)
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{
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struct ethernet_req_params params;
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int ret;
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memset(¶ms, 0, sizeof(params));
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params.qav_param.queue_id = queue_id;
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params.qav_param.enabled = enable;
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params.qav_param.type = ETHERNET_QAV_PARAM_TYPE_STATUS;
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/* Disable or enable Qav for a queue */
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ret = net_mgmt(NET_REQUEST_ETHERNET_SET_QAV_PARAM,
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iface, ¶ms,
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sizeof(struct ethernet_req_params));
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if (ret) {
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LOG_ERR("Cannot %s Qav for queue %d for interface %p",
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enable ? "enable" : "disable",
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queue_id, iface);
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}
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}
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static void qav_set_bandwidth_and_slope(struct net_if *iface,
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int queue_id,
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unsigned int bandwidth,
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unsigned int idle_slope)
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{
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struct ethernet_req_params params;
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int ret;
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memset(¶ms, 0, sizeof(params));
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params.qav_param.queue_id = queue_id;
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params.qav_param.delta_bandwidth = bandwidth;
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params.qav_param.type = ETHERNET_QAV_PARAM_TYPE_DELTA_BANDWIDTH;
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ret = net_mgmt(NET_REQUEST_ETHERNET_SET_QAV_PARAM,
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iface, ¶ms,
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sizeof(struct ethernet_req_params));
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if (ret) {
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LOG_ERR("Cannot set Qav delta bandwidth %u for "
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"queue %d for interface %p",
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bandwidth, queue_id, iface);
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}
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params.qav_param.idle_slope = idle_slope;
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params.qav_param.type = ETHERNET_QAV_PARAM_TYPE_IDLE_SLOPE;
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ret = net_mgmt(NET_REQUEST_ETHERNET_SET_QAV_PARAM,
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iface, ¶ms,
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sizeof(struct ethernet_req_params));
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if (ret) {
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LOG_ERR("Cannot set Qav idle slope %u for "
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"queue %d for interface %p",
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idle_slope, queue_id, iface);
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}
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}
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.. _IEEE 802.1Qav-2009 standard:
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https://standards.ieee.org/standard/802_1Qav-2009.html
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