[PATCH 03/17] mlx4_en: optimize adaptive moderation algorithm for better latency
From: Yevgeny Petrilin <hidden>
Date: 2011-03-07 15:01:03
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Signed-off-by: Yevgeny Petrilin <redacted> --- drivers/net/mlx4/en_netdev.c | 18 +++++------------- drivers/net/mlx4/mlx4_en.h | 1 + 2 files changed, 6 insertions(+), 13 deletions(-)
diff --git a/drivers/net/mlx4/en_netdev.c b/drivers/net/mlx4/en_netdev.c
index 56627c2..b1180dd 100644
--- a/drivers/net/mlx4/en_netdev.c
+++ b/drivers/net/mlx4/en_netdev.c@@ -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",
diff --git a/drivers/net/mlx4/mlx4_en.h b/drivers/net/mlx4/mlx4_en.h
index dfed6a0..5387c4e 100644
--- a/drivers/net/mlx4/mlx4_en.h
+++ b/drivers/net/mlx4/mlx4_en.h@@ -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
--
1.6.0.2