[dpdk-dev] Unit for tx_rate in rte_eth_set_queue_rate_limit?
Thomas Monjalon
thomas.monjalon at 6wind.com
Tue Oct 20 14:38:54 CEST 2015
2015-10-20 14:20, Simon Kågström:
> Hi!
>
> What is the unit of the tx_rate parameter to the
> rte_eth_set_queue_rate_limit function? It's documented as
>
> /**
> * Set the rate limitation for a queue on an Ethernet device.
> *
> * @param port_id
> * The port identifier of the Ethernet device.
> * @param queue_idx
> * The queue id.
> * @param tx_rate
> * The tx rate allocated from the total link speed for this queue.
> * @return
> * - (0) if successful.
> * - (-ENOTSUP) if hardware doesn't support this feature.
> * - (-ENODEV) if *port_id* invalid.
> * - (-EINVAL) if bad parameter.
> */
> int rte_eth_set_queue_rate_limit(uint8_t port_id, uint16_t queue_idx,
> uint16_t tx_rate);
>
> I parse this as meaning a percentage of total link speed, i.e., on a 10
> Gbps link, 50 would mean 5Gbps, 10 means 1Gbps etc. Is this correct?
It's implemented only in ixgbe:
/* Calculate the rate factor values to set */
rf_int = (uint32_t)link_speed / (uint32_t)tx_rate;
rf_dec = (uint32_t)link_speed % (uint32_t)tx_rate;
rf_dec = (rf_dec << IXGBE_RTTBCNRC_RF_INT_SHIFT) / tx_rate;
bcnrc_val = IXGBE_RTTBCNRC_RS_ENA;
bcnrc_val |= ((rf_int << IXGBE_RTTBCNRC_RF_INT_SHIFT) &
IXGBE_RTTBCNRC_RF_INT_MASK_M);
bcnrc_val |= (rf_dec & IXGBE_RTTBCNRC_RF_DEC_MASK);
So you just need to check the datasheet and send a patch to make it clear :)
Thanks
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