> 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 mandates a core-to-single-queue mapping (that is, multiple
> queued per device are supported, but they have to be polled on different
> cores).
>
> This design is using PMD RX callbacks.
>
> 1. UMWAIT/UMONITOR:
>
> When a certain threshold of empty polls is reached, the core will go
> into a power optimized sleep while waiting on an address of next RX
> descriptor to be written to.
>
> 2. Pause instruction
>
> Instead of move the core into deeper C state, this method uses the
> pause instruction to avoid busy polling.
>
> 3. Frequency scaling
> Reuse existing DPDK power library to scale up/down core frequency
> depending on traffic volume.
>
> Signed-off-by: Liang Ma <liang.j...@intel.com>
> Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
> Acked-by: David Hunt <david.h...@intel.com>
> ---
>
> Notes:
> v7:
> - Fixed race condition (Konstantin)
> - Slight rework of the structure of monitor code
> - Added missing inline for wakeup
>
> v6:
> - Added wakeup mechanism for UMWAIT
> - Removed memory allocation (everything is now allocated statically)
> - Fixed various typos and comments
> - Check for invalid queue ID
> - Moved release notes to this patch
>
> v5:
> - Make error checking more robust
> - Prevent initializing scaling if ACPI or PSTATE env wasn't set
> - Prevent initializing UMWAIT path if PMD doesn't support get_wake_addr
> - Add some debug logging
> - Replace x86-specific code path to generic path using the intrinsic check
>
> doc/guides/rel_notes/release_20_11.rst | 11 +
> lib/librte_power/meson.build | 5 +-
> lib/librte_power/rte_power_pmd_mgmt.c | 320 +++++++++++++++++++++++++
> lib/librte_power/rte_power_pmd_mgmt.h | 92 +++++++
> lib/librte_power/rte_power_version.map | 4 +
> 5 files changed, 430 insertions(+), 2 deletions(-)
> 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/doc/guides/rel_notes/release_20_11.rst
> b/doc/guides/rel_notes/release_20_11.rst
> index 4c6a615ce9..a814c67d54 100644
> --- a/doc/guides/rel_notes/release_20_11.rst
> +++ b/doc/guides/rel_notes/release_20_11.rst
> @@ -204,6 +204,17 @@ New Features
>
> * Added support to update subport rate dynamically.
>
> +* **Add PMD power management mechanism**
> +
> + 3 new Ethernet PMD power management mechanism is added through existing
> + RX callback infrastructure.
> +
> + * Add power saving scheme based on UMWAIT instruction (x86 only)
> + * Add power saving scheme based on ``rte_pause()``
> + * Add power saving scheme based on frequency scaling through the power
> library
> + * Add new EXPERIMENTAL API ``rte_power_pmd_mgmt_queue_enable()``
> + * Add new EXPERIMENTAL API ``rte_power_pmd_mgmt_queue_disable()``
> +
>
> Removed Items
> -------------
....
> +
> +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;
> +
> + RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -EINVAL);
> + dev = &rte_eth_devices[port_id];
> +
> + /* check if queue id is valid */
> + if (queue_id >= dev->data->nb_rx_queues ||
> + queue_id >= RTE_MAX_QUEUES_PER_PORT) {
> + return -EINVAL;
> + }
> +
> + queue_cfg = &port_cfg[port_id][queue_id];
> +
> + if (queue_cfg->pwr_mgmt_state == PMD_MGMT_ENABLED) {
> + ret = -EINVAL;
> + goto end;
> + }
> +
> + switch (mode) {
> + case RTE_POWER_MGMT_TYPE_WAIT:
> + {
> + /* check if rte_power_monitor is supported */
> + uint64_t dummy_expected, dummy_mask;
> + struct rte_cpu_intrinsics i;
> + volatile void *dummy_addr;
> + uint8_t dummy_sz;
> +
> + rte_cpu_get_intrinsics_support(&i);
> +
> + if (!i.power_monitor) {
> + RTE_LOG(DEBUG, POWER, "Monitoring intrinsics are not
> supported\n");
> + ret = -ENOTSUP;
> + goto end;
> + }
> +
> + /* check if the device supports the necessary PMD API */
> + if (rte_eth_get_wake_addr(port_id, queue_id,
> + &dummy_addr, &dummy_expected,
> + &dummy_mask, &dummy_sz) == -ENOTSUP) {
> + RTE_LOG(DEBUG, POWER, "The device does not support
> rte_eth_rxq_ring_addr_get\n");
> + ret = -ENOTSUP;
> + goto end;
> + }
> + /* initialize UMWAIT spinlock */
> + rte_spinlock_init(&queue_cfg->umwait_lock);
Still looks excessive and possibly error prone to me.
Apart from that:
Acked-by: Konstantin Ananyev <konstantin.anan...@intel.com>
> +
> + /* initialize data before enabling the callback */
> + queue_cfg->empty_poll_stats = 0;
> + queue_cfg->cb_mode = mode;
> + queue_cfg->pwr_mgmt_state = PMD_MGMT_ENABLED;
> +
> + queue_cfg->cur_cb = rte_eth_add_rx_callback(port_id, queue_id,
> + clb_umwait, NULL);
> + break;
> + }
> + case RTE_POWER_MGMT_TYPE_SCALE:
> + {
> + enum power_management_env env;
> + /* only PSTATE and ACPI modes are supported */
> + if (!rte_power_check_env_supported(PM_ENV_ACPI_CPUFREQ) &&
> + !rte_power_check_env_supported(
> + PM_ENV_PSTATE_CPUFREQ)) {
> + RTE_LOG(DEBUG, POWER, "Neither ACPI nor PSTATE modes
> are supported\n");
> + ret = -ENOTSUP;
> + goto end;
> + }
> + /* ensure we could initialize the power library */
> + if (rte_power_init(lcore_id)) {
> + ret = -EINVAL;
> + goto end;
> + }
> + /* ensure we initialized the correct env */
> + env = rte_power_get_env();
> + if (env != PM_ENV_ACPI_CPUFREQ &&
> + env != PM_ENV_PSTATE_CPUFREQ) {
> + RTE_LOG(DEBUG, POWER, "Neither ACPI nor PSTATE modes
> were initialized\n");
> + ret = -ENOTSUP;
> + goto end;
> + }
> + /* initialize data before enabling the callback */
> + queue_cfg->empty_poll_stats = 0;
> + queue_cfg->cb_mode = mode;
> + queue_cfg->pwr_mgmt_state = PMD_MGMT_ENABLED;
> +
> + queue_cfg->cur_cb = rte_eth_add_rx_callback(port_id,
> + queue_id, clb_scale_freq, NULL);
> + break;
> + }
> + case RTE_POWER_MGMT_TYPE_PAUSE:
> + /* initialize data before enabling the callback */
> + queue_cfg->empty_poll_stats = 0;
> + queue_cfg->cb_mode = mode;
> + queue_cfg->pwr_mgmt_state = PMD_MGMT_ENABLED;
> +
> + queue_cfg->cur_cb = rte_eth_add_rx_callback(port_id, queue_id,
> + clb_pause, NULL);
> + break;
> + }
> + ret = 0;
> +
> +end:
> + return ret;
> +}
> +
