text: /* SPDX-License-Identifier: BSD-3-Clause
   * Copyright(c) 2017 Intel Corporation
   */
  
  #include <rte_common.h>
  #include <rte_ethdev.h>
  #include <rte_malloc.h>
  #include <rte_metrics.h>
  #include <rte_bitrate.h>
  
  /*
   * Persistent bit-rate data.
   * @internal
   */
  struct rte_stats_bitrate {
  	uint64_t last_ibytes;
  	uint64_t last_obytes;
  	uint64_t peak_ibits;
  	uint64_t peak_obits;
  	uint64_t mean_ibits;
  	uint64_t mean_obits;
  	uint64_t ewma_ibits;
  	uint64_t ewma_obits;
  };
  
  struct rte_stats_bitrates {
  	struct rte_stats_bitrate port_stats[RTE_MAX_ETHPORTS];
  	uint16_t id_stats_set;
  };
  
  struct rte_stats_bitrates *
  rte_stats_bitrate_create(void)
  {
  	return rte_zmalloc(NULL, sizeof(struct rte_stats_bitrates),
  		RTE_CACHE_LINE_SIZE);
  }
  
  int
  rte_stats_bitrate_reg(struct rte_stats_bitrates *bitrate_data)
  {
  	const char * const names[] = {
  		"ewma_bits_in", "ewma_bits_out",
  		"mean_bits_in", "mean_bits_out",
  		"peak_bits_in", "peak_bits_out",
  	};
  	int return_value;
  
  	if (bitrate_data == NULL)
  		return -EINVAL;
  
  	return_value = rte_metrics_reg_names(&names[0], RTE_DIM(names));
  	if (return_value >= 0)
  		bitrate_data->id_stats_set = return_value;
  	return return_value;
  }
  
  int
  rte_stats_bitrate_calc(struct rte_stats_bitrates *bitrate_data,
  			uint16_t port_id)
  {
  	struct rte_stats_bitrate *port_data;
  	struct rte_eth_stats eth_stats;
  	int ret_code;
  	uint64_t cnt_bits;
  	int64_t delta;
  	const int64_t alpha_percent = 20;
  	uint64_t values[6];
  	int ret;
  
  	if (bitrate_data == NULL)
  		return -EINVAL;
  
  	ret_code = rte_eth_stats_get(port_id, &eth_stats);
  	if (ret_code != 0)
  		return ret_code;
  
  	port_data = &bitrate_data->port_stats[port_id];
  
  	/* Incoming bitrate. This is an iteratively calculated EWMA
  	 * (Exponentially Weighted Moving Average) that uses a
  	 * weighting factor of alpha_percent. An unsmoothed mean
  	 * for just the current time delta is also calculated for the
  	 * benefit of people who don't understand signal processing.
  	 */
  	cnt_bits = (eth_stats.ibytes - port_data->last_ibytes) << 3;
  	port_data->last_ibytes = eth_stats.ibytes;
  	if (cnt_bits > port_data->peak_ibits)
  		port_data->peak_ibits = cnt_bits;
  	delta = cnt_bits;
  	delta -= port_data->ewma_ibits;
  	/* The +-50 fixes integer rounding during division */
  	if (delta > 0)
  		delta = (delta * alpha_percent + 50) / 100;
  	else
  		delta = (delta * alpha_percent - 50) / 100;
  	port_data->ewma_ibits += delta;
  	/* Integer roundoff prevents EWMA between 0 and (100/alpha_percent)
  	 * ever reaching zero in no-traffic conditions
  	 */
  	if (cnt_bits == 0 && delta == 0)
  		port_data->ewma_ibits = 0;
  	port_data->mean_ibits = cnt_bits;
  
  	/* Outgoing bitrate (also EWMA) */
  	cnt_bits = (eth_stats.obytes - port_data->last_obytes) << 3;
  	port_data->last_obytes = eth_stats.obytes;
  	if (cnt_bits > port_data->peak_obits)
  		port_data->peak_obits = cnt_bits;
  	delta = cnt_bits;
  	delta -= port_data->ewma_obits;
  	if (delta > 0)
  		delta = (delta * alpha_percent + 50) / 100;
  	else
  		delta = (delta * alpha_percent - 50) / 100;
  	port_data->ewma_obits += delta;
  	if (cnt_bits == 0 && delta == 0)
  		port_data->ewma_obits = 0;
  	port_data->mean_obits = cnt_bits;
  
  	values[0] = port_data->ewma_ibits;
  	values[1] = port_data->ewma_obits;
  	values[2] = port_data->mean_ibits;
  	values[3] = port_data->mean_obits;
  	values[4] = port_data->peak_ibits;
  	values[5] = port_data->peak_obits;
  	ret = rte_metrics_update_values(port_id, bitrate_data->id_stats_set,
  		values, RTE_DIM(values));
  	if (ret < 0)
  		return ret;
  
  	return 0;
  }
  