[PATCH] ixgbe: add a callback to set the maximum transmit bitrate

From: Rostislav Pehlivanov
Date: Wed Jan 27 2016 - 13:33:49 EST


This commit adds a callback which allows to adjust the maximum transmit
bitrate the card can output. This makes it possible to get a smooth
traffic instead of the default burst-y behaviour when trying to output
e.g. a video stream.

Much of the logic needed to get a correct bcnrc_val was taken from the
ixgbe_set_vf_rate_limit() function.

Signed-off-by: Rostislav Pehlivanov <atomnuker@xxxxxxxxx>
---
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 31 ++++++++++++++++++++++++++
drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c | 2 +-
drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.h | 1 +
3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index c4003a8..d05455c 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -1084,6 +1084,36 @@ static void ixgbe_tx_timeout_reset(struct ixgbe_adapter *adapter)
}

/**
+ * ixgbe_tx_maxrate - callback to set the maximum per-queue bitrate
+ **/
+static int ixgbe_tx_maxrate(struct net_device *netdev,
+ int queue_index, u32 maxrate)
+{
+ struct ixgbe_adapter *adapter = netdev_priv(netdev);
+ struct ixgbe_hw *hw = &adapter->hw;
+ u32 bcnrc_val = ixgbe_link_mbps(adapter);
+
+ if (!maxrate)
+ return 0;
+
+ /* Calculate the rate factor values to set */
+ bcnrc_val <<= IXGBE_RTTBCNRC_RF_INT_SHIFT;
+ bcnrc_val /= maxrate;
+
+ /* clear everything but the rate factor */
+ bcnrc_val &= IXGBE_RTTBCNRC_RF_INT_MASK |
+ IXGBE_RTTBCNRC_RF_DEC_MASK;
+
+ /* enable the rate scheduler */
+ bcnrc_val |= IXGBE_RTTBCNRC_RS_ENA;
+
+ IXGBE_WRITE_REG(hw, IXGBE_RTTDQSEL, queue_index);
+ IXGBE_WRITE_REG(hw, IXGBE_RTTBCNRC, bcnrc_val);
+
+ return 0;
+}
+
+/**
* ixgbe_clean_tx_irq - Reclaim resources after transmit completes
* @q_vector: structure containing interrupt and ring information
* @tx_ring: tx ring to clean
@@ -8646,6 +8676,7 @@ static const struct net_device_ops ixgbe_netdev_ops = {
.ndo_set_mac_address = ixgbe_set_mac,
.ndo_change_mtu = ixgbe_change_mtu,
.ndo_tx_timeout = ixgbe_tx_timeout,
+ .ndo_set_tx_maxrate = ixgbe_tx_maxrate,
.ndo_vlan_rx_add_vid = ixgbe_vlan_rx_add_vid,
.ndo_vlan_rx_kill_vid = ixgbe_vlan_rx_kill_vid,
.ndo_do_ioctl = ixgbe_ioctl,
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
index 8025a3f..f9ca7d5 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
@@ -1395,7 +1395,7 @@ out:
return err;
}

-static int ixgbe_link_mbps(struct ixgbe_adapter *adapter)
+int ixgbe_link_mbps(struct ixgbe_adapter *adapter)
{
switch (adapter->link_speed) {
case IXGBE_LINK_SPEED_100_FULL:
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.h
index dad9257..47e65e2 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.h
@@ -44,6 +44,7 @@ void ixgbe_ping_all_vfs(struct ixgbe_adapter *adapter);
int ixgbe_ndo_set_vf_mac(struct net_device *netdev, int queue, u8 *mac);
int ixgbe_ndo_set_vf_vlan(struct net_device *netdev, int queue, u16 vlan,
u8 qos);
+int ixgbe_link_mbps(struct ixgbe_adapter *adapter);
int ixgbe_ndo_set_vf_bw(struct net_device *netdev, int vf, int min_tx_rate,
int max_tx_rate);
int ixgbe_ndo_set_vf_spoofchk(struct net_device *netdev, int vf, bool setting);
--
2.7.0