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mlx4_en: optimize adaptive moderation algorithm for better latency

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Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yevgeny Petrilin 2011-03-22 22:37:36 +00:00 committed by David S. Miller
parent 39f17b44aa
commit 46afd0fb01
2 changed files with 6 additions and 13 deletions
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18
drivers/net/mlx4/en_netdev.c
View file

@ -417,7 +417,6 @@ static void mlx4_en_auto_moderation(struct mlx4_en_priv *priv)
unsigned long avg_pkt_size;
unsigned long rx_packets;
unsigned long rx_bytes;
unsigned long rx_byte_diff;
unsigned long tx_packets;
unsigned long tx_pkt_diff;
unsigned long rx_pkt_diff;
@ -441,25 +440,20 @@ static void mlx4_en_auto_moderation(struct mlx4_en_priv *priv)
rx_pkt_diff = ((unsigned long) (rx_packets -
priv->last_moder_packets));
packets = max(tx_pkt_diff, rx_pkt_diff);
rx_byte_diff = rx_bytes - priv->last_moder_bytes;
rx_byte_diff = rx_byte_diff ? rx_byte_diff : 1;
rate = packets * HZ / period;
avg_pkt_size = packets ? ((unsigned long) (rx_bytes -
priv->last_moder_bytes)) / packets : 0;
/* Apply auto-moderation only when packet rate exceeds a rate that
* it matters */
if (rate > MLX4_EN_RX_RATE_THRESH) {
if (rate > MLX4_EN_RX_RATE_THRESH && avg_pkt_size > MLX4_EN_AVG_PKT_SMALL) {
/* If tx and rx packet rates are not balanced, assume that
* traffic is mainly BW bound and apply maximum moderation.
* Otherwise, moderate according to packet rate */
if (2 * tx_pkt_diff > 3 * rx_pkt_diff &&
rx_pkt_diff / rx_byte_diff <
MLX4_EN_SMALL_PKT_SIZE)
moder_time = priv->rx_usecs_low;
else if (2 * rx_pkt_diff > 3 * tx_pkt_diff)
if (2 * tx_pkt_diff > 3 * rx_pkt_diff ||
2 * rx_pkt_diff > 3 * tx_pkt_diff) {
moder_time = priv->rx_usecs_high;
else {
} else {
if (rate < priv->pkt_rate_low)
moder_time = priv->rx_usecs_low;
else if (rate > priv->pkt_rate_high)
@ -471,9 +465,7 @@ static void mlx4_en_auto_moderation(struct mlx4_en_priv *priv)
priv->rx_usecs_low;
}
} else {
/* When packet rate is low, use default moderation rather than
* 0 to prevent interrupt storms if traffic suddenly increases */
moder_time = priv->rx_usecs;
moder_time = priv->rx_usecs_low;
}
en_dbg(INTR, priv, "tx rate:%lu rx_rate:%lu\n",

1
drivers/net/mlx4/mlx4_en.h
View file

@ -124,6 +124,7 @@ enum {
#define MLX4_EN_RX_SIZE_THRESH 1024
#define MLX4_EN_RX_RATE_THRESH (1000000 / MLX4_EN_RX_COAL_TIME_HIGH)
#define MLX4_EN_SAMPLE_INTERVAL 0
#define MLX4_EN_AVG_PKT_SMALL 256
#define MLX4_EN_AUTO_CONF 0xffff