> Add a simple on/off switch that will enable saving power when no
> packets are arriving. It is based on counting the number of empty
> polls and, when the number reaches a certain threshold, entering an
> architecture-defined optimized power state that will either wait
> until a TSC timestamp expires, or when packets arrive.
>
> This API support 1 port to multiple core use case.
>
> This design leverage RX Callback mechnaism which allow three
> different power management methodology co exist.
>
> 1. umwait/umonitor:
>
> The TSC timestamp is automatically calculated using current
> link speed and RX descriptor ring size, such that the sleep
> time is not longer than it would take for a NIC to fill its
> entire RX descriptor ring.
>
> 2. Pause instruction
>
> Instead of move the core into deeper C state, this lightweight
> method use Pause instruction to relief the processor from
> busy polling.
>
> 3. Frequency Scaling
> Reuse exist rte power library to scale up/down core frequency
> depend on traffic volume.
>
> Signed-off-by: Liang Ma <liang.j...@intel.com>
> Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
> ---
> lib/librte_power/meson.build | 5 +-
> lib/librte_power/pmd_mgmt.h | 49 ++++++
> lib/librte_power/rte_power_pmd_mgmt.c | 208 +++++++++++++++++++++++++
> lib/librte_power/rte_power_pmd_mgmt.h | 88 +++++++++++
> lib/librte_power/rte_power_version.map | 4 +
> 5 files changed, 352 insertions(+), 2 deletions(-)
> create mode 100644 lib/librte_power/pmd_mgmt.h
> create mode 100644 lib/librte_power/rte_power_pmd_mgmt.c
> create mode 100644 lib/librte_power/rte_power_pmd_mgmt.h
>
> diff --git a/lib/librte_power/meson.build b/lib/librte_power/meson.build
> index 78c031c943..cc3c7a8646 100644
> --- a/lib/librte_power/meson.build
> +++ b/lib/librte_power/meson.build
> @@ -9,6 +9,7 @@ sources = files('rte_power.c', 'power_acpi_cpufreq.c',
> 'power_kvm_vm.c', 'guest_channel.c',
> 'rte_power_empty_poll.c',
> 'power_pstate_cpufreq.c',
> + 'rte_power_pmd_mgmt.c',
> 'power_common.c')
> -headers = files('rte_power.h','rte_power_empty_poll.h')
> -deps += ['timer']
> +headers =
> files('rte_power.h','rte_power_empty_poll.h','rte_power_pmd_mgmt.h')
> +deps += ['timer' ,'ethdev']
> diff --git a/lib/librte_power/pmd_mgmt.h b/lib/librte_power/pmd_mgmt.h
> new file mode 100644
> index 0000000000..756fbe20f7
> --- /dev/null
> +++ b/lib/librte_power/pmd_mgmt.h
> @@ -0,0 +1,49 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2010-2020 Intel Corporation
> + */
> +
> +#ifndef _PMD_MGMT_H
> +#define _PMD_MGMT_H
> +
> +/**
> + * @file
> + * Power Management
> + */
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +/**
> + * Possible power management states of an ethdev port.
> + */
> +enum pmd_mgmt_state {
> + /** Device power management is disabled. */
> + PMD_MGMT_DISABLED = 0,
> + /** Device power management is enabled. */
> + PMD_MGMT_ENABLED,
> +};
> +
> +struct pmd_queue_cfg {
> + enum pmd_mgmt_state pwr_mgmt_state;
> + /**< Power mgmt Callback mode */
> + enum rte_power_pmd_mgmt_type cb_mode;
> + /**< Empty poll number */
> + uint16_t empty_poll_stats;
> + /**< Callback instance */
> + const struct rte_eth_rxtx_callback *cur_cb;
> +} __rte_cache_aligned;
> +
> +struct pmd_port_cfg {
> + int ref_cnt;
> + struct pmd_queue_cfg *queue_cfg;
> +} __rte_cache_aligned;
> +
> +
> +
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif
> diff --git a/lib/librte_power/rte_power_pmd_mgmt.c
> b/lib/librte_power/rte_power_pmd_mgmt.c
> new file mode 100644
> index 0000000000..35d2af46a4
> --- /dev/null
> +++ b/lib/librte_power/rte_power_pmd_mgmt.c
> @@ -0,0 +1,208 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2010-2020 Intel Corporation
> + */
> +
> +#include <rte_lcore.h>
> +#include <rte_cycles.h>
> +#include <rte_malloc.h>
> +#include <rte_ethdev.h>
> +#include <rte_power_intrinsics.h>
> +
> +#include "rte_power_pmd_mgmt.h"
> +#include "pmd_mgmt.h"
> +
> +
> +#define EMPTYPOLL_MAX 512
> +#define PAUSE_NUM 64
> +
> +static struct pmd_port_cfg port_cfg[RTE_MAX_ETHPORTS];
> +
> +static uint16_t
> +rte_power_mgmt_umwait(uint16_t port_id, uint16_t qidx,
> + struct rte_mbuf **pkts __rte_unused, uint16_t nb_rx,
> + uint16_t max_pkts __rte_unused, void *_ __rte_unused)
> +{
> +
> + struct pmd_queue_cfg *q_conf;
> + q_conf = &port_cfg[port_id].queue_cfg[qidx];
> +
> + if (unlikely(nb_rx == 0)) {
> + q_conf->empty_poll_stats++;
> + if (unlikely(q_conf->empty_poll_stats > EMPTYPOLL_MAX)) {
Here and in other places - wouldn't it be better to empty_poll_max as
configurable
parameter, instead of constant value?
> + volatile void *target_addr;
> + uint64_t expected, mask;
> + uint16_t ret;
> +
> + /*
> + * get address of next descriptor in the RX
> + * ring for this queue, as well as expected
> + * value and a mask.
> + */
> + ret = rte_eth_get_wake_addr(port_id, qidx,
> + &target_addr, &expected,
> + &mask);
> + if (ret == 0)
> + /* -1ULL is maximum value for TSC */
> + rte_power_monitor(target_addr,
> + expected, mask,
> + 0, -1ULL);
Why not make timeout a user specified parameter?
> + }
> + } else
> + q_conf->empty_poll_stats = 0;
> +
> + return nb_rx;
> +}
> +
> +static uint16_t
> +rte_power_mgmt_pause(uint16_t port_id, uint16_t qidx,
> + struct rte_mbuf **pkts __rte_unused, uint16_t nb_rx,
> + uint16_t max_pkts __rte_unused, void *_ __rte_unused)
> +{
> + struct pmd_queue_cfg *q_conf;
> + int i;
> + q_conf = &port_cfg[port_id].queue_cfg[qidx];
> +
> + if (unlikely(nb_rx == 0)) {
> + q_conf->empty_poll_stats++;
> + if (unlikely(q_conf->empty_poll_stats > EMPTYPOLL_MAX)) {
> + for (i = 0; i < PAUSE_NUM; i++)
> + rte_pause();
Just rte_delay_us(timeout) instead of this loop?
> + }
> + } else
> + q_conf->empty_poll_stats = 0;
> +
> + return nb_rx;
> +}
> +
> +static uint16_t
> +rte_power_mgmt_scalefreq(uint16_t port_id, uint16_t qidx,
> + struct rte_mbuf **pkts __rte_unused, uint16_t nb_rx,
> + uint16_t max_pkts __rte_unused, void *_ __rte_unused)
> +{
> + struct pmd_queue_cfg *q_conf;
> + q_conf = &port_cfg[port_id].queue_cfg[qidx];
> +
> + if (unlikely(nb_rx == 0)) {
> + q_conf->empty_poll_stats++;
> + if (unlikely(q_conf->empty_poll_stats > EMPTYPOLL_MAX)) {
> + /*scale down freq */
> + rte_power_freq_min(rte_lcore_id());
> +
> + }
> + } else {
> + q_conf->empty_poll_stats = 0;
> + /* scal up freq */
> + rte_power_freq_max(rte_lcore_id());
> + }
> +
> + return nb_rx;
> +}
> +
Probably worth to mention in comments that these functions enable/disable
are not MT safe.
> +int
> +rte_power_pmd_mgmt_queue_enable(unsigned int lcore_id,
> + uint16_t port_id,
> + uint16_t queue_id,
> + enum rte_power_pmd_mgmt_type mode)
> +{
> + struct rte_eth_dev *dev;
> + struct pmd_queue_cfg *queue_cfg;
> + int ret = 0;
> +
> + RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -EINVAL);
> + dev = &rte_eth_devices[port_id];
> +
> + if (port_cfg[port_id].queue_cfg == NULL) {
> + port_cfg[port_id].ref_cnt = 0;
> + /* allocate memory for empty poll stats */
> + port_cfg[port_id].queue_cfg = rte_malloc_socket(NULL,
> + sizeof(struct pmd_queue_cfg)
> + * RTE_MAX_QUEUES_PER_PORT,
> + 0, dev->data->numa_node);
> + if (port_cfg[port_id].queue_cfg == NULL)
> + return -ENOMEM;
> + }
> +
> + queue_cfg = &port_cfg[port_id].queue_cfg[queue_id];
> +
> + if (queue_cfg->pwr_mgmt_state == PMD_MGMT_ENABLED) {
> + ret = -EINVAL;
> + goto failure_handler;
> + }
> +
> + switch (mode) {
> + case RTE_POWER_MGMT_TYPE_WAIT:
> + if (!rte_cpu_get_flag_enabled(RTE_CPUFLAG_WAITPKG)) {
> + ret = -ENOTSUP;
> + goto failure_handler;
> + }
> + queue_cfg->cur_cb = rte_eth_add_rx_callback(port_id, queue_id,
> + rte_power_mgmt_umwait, NULL);
> + break;
> + case RTE_POWER_MGMT_TYPE_SCALE:
> + /* init scale freq */
> + if (rte_power_init(lcore_id)) {
> + ret = -EINVAL;
> + goto failure_handler;
> + }
> + queue_cfg->cur_cb = rte_eth_add_rx_callback(port_id, queue_id,
> + rte_power_mgmt_scalefreq, NULL);
> + break;
> + case RTE_POWER_MGMT_TYPE_PAUSE:
> + queue_cfg->cur_cb = rte_eth_add_rx_callback(port_id, queue_id,
> + rte_power_mgmt_pause, NULL);
> + break;
default:
....
> + }
> + queue_cfg->cb_mode = mode;
> + port_cfg[port_id].ref_cnt++;
> + queue_cfg->pwr_mgmt_state = PMD_MGMT_ENABLED;
> + return ret;
> +
> +failure_handler:
> + if (port_cfg[port_id].ref_cnt == 0) {
> + rte_free(port_cfg[port_id].queue_cfg);
> + port_cfg[port_id].queue_cfg = NULL;
> + }
> + return ret;
> +}
> +
> +int
> +rte_power_pmd_mgmt_queue_disable(unsigned int lcore_id,
> + uint16_t port_id,
> + uint16_t queue_id)
> +{
> + struct pmd_queue_cfg *queue_cfg;
> +
> + if (port_cfg[port_id].ref_cnt <= 0)
> + return -EINVAL;
> +
> + queue_cfg = &port_cfg[port_id].queue_cfg[queue_id];
> +
> + if (queue_cfg->pwr_mgmt_state == PMD_MGMT_DISABLED)
> + return -EINVAL;
> +
> + switch (queue_cfg->cb_mode) {
> + case RTE_POWER_MGMT_TYPE_WAIT:
Think we need wakeup(lcore_id) here.
> + case RTE_POWER_MGMT_TYPE_PAUSE:
> + rte_eth_remove_rx_callback(port_id, queue_id,
> + queue_cfg->cur_cb);
> + break;
> + case RTE_POWER_MGMT_TYPE_SCALE:
> + rte_power_freq_max(lcore_id);
> + rte_eth_remove_rx_callback(port_id, queue_id,
> + queue_cfg->cur_cb);
> + rte_power_exit(lcore_id);
> + break;
> + }
> + /* it's not recommend to free callback instance here.
> + * it cause memory leak which is a known issue.
> + */
> + queue_cfg->cur_cb = NULL;
> + queue_cfg->pwr_mgmt_state = PMD_MGMT_DISABLED;
> + port_cfg[port_id].ref_cnt--;
> +
> + if (port_cfg[port_id].ref_cnt == 0) {
> + rte_free(port_cfg[port_id].queue_cfg);
It is not safe to do so, unless device is already stopped.
Otherwise you need some sync mechanism here (hand-made as bpf lib, or rcu
online/offline, or...)
> + port_cfg[port_id].queue_cfg = NULL;
> + }
> + return 0;
> +}
