Re: [dpdk-dev] [PATCH] ixgbe: fix multi-process support

["Qiu, Michael" <michael.qiu@intel.com>]

On 12/4/2014 7:49 PM, Bruce Richardson wrote:
> When using multiple processes, the TX function used in all processes
> should be the same, otherwise the secondary processes cannot transmit
> more than tx-ring-size - 1 packets.
> To achieve this, we extract out the code to select the ixgbe TX function
> to be used into a separate function inside the ixgbe driver, and call
> that from a secondary process when it is attaching to an
> already-configured NIC.
>
> Testing with symmetric MP app shows that we are able to RX and TX from
> both primary and secondary processes once this patch is applied.
>
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
>  lib/librte_pmd_ixgbe/ixgbe_ethdev.c   |  7 +++-
>  lib/librte_pmd_ixgbe/ixgbe_rxtx.c     | 61 +++++++++++++++++++++--------------
>  lib/librte_pmd_ixgbe/ixgbe_rxtx.h     |  7 ++++
>  lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c |  3 ++
>  4 files changed, 52 insertions(+), 26 deletions(-)
>
> diff --git a/lib/librte_pmd_ixgbe/ixgbe_ethdev.c b/lib/librte_pmd_ixgbe/ixgbe_ethdev.c
> index 937fc3c..4abab25 100644
> --- a/lib/librte_pmd_ixgbe/ixgbe_ethdev.c
> +++ b/lib/librte_pmd_ixgbe/ixgbe_ethdev.c
> @@ -68,6 +68,7 @@
>  #include "ixgbe/ixgbe_common.h"
>  #include "ixgbe_ethdev.h"
>  #include "ixgbe_bypass.h"
> +#include "ixgbe_rxtx.h"
>  
>  /*
>   * High threshold controlling when to start sending XOFF frames. Must be at
> @@ -743,8 +744,12 @@ eth_ixgbe_dev_init(__attribute__((unused)) struct eth_driver *eth_drv,
>  
>  	/* for secondary processes, we don't initialise any further as primary
>  	 * has already done this work. Only check we don't need a different
> -	 * RX function */
> +	 * RX and TX function */

Can it be more beautiful? like:
/*
  * XXXXXXXX
  */

But not a big deal.

>  	if (rte_eal_process_type() != RTE_PROC_PRIMARY){
> +		struct igb_tx_queue *txq;
> +		txq = eth_dev->data->tx_queues[eth_dev->data->nb_tx_queues-1];

Here why chose the last TX queue?

> +		set_tx_function(eth_dev, txq);
> +
>  		if (eth_dev->data->scattered_rx)
>  			eth_dev->rx_pkt_burst = ixgbe_recv_scattered_pkts;
>  		return 0;
> diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> index 5c36bff..263c815 100644
> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> @@ -1771,6 +1771,40 @@ static struct ixgbe_txq_ops def_txq_ops = {
>  	.reset = ixgbe_reset_tx_queue,
>  };
>  
> +/* takes an ethdev and a queue and sets up the tx function to be used based on
> + * the queue parameters. Used in tx_queue_setup by primary process and then
> + * in dev_init by secondary process when attaching to an existing ethdev
> + */
> +void
> +set_tx_function(struct rte_eth_dev* dev, struct igb_tx_queue* txq)
> +{
> +	/* Use a simple Tx queue (no offloads, no multi segs) if possible */
> +	if (((txq->txq_flags & IXGBE_SIMPLE_FLAGS) == IXGBE_SIMPLE_FLAGS)
> +			&& (txq->tx_rs_thresh >= RTE_PMD_IXGBE_TX_MAX_BURST)) {
> +			PMD_INIT_LOG(INFO, "Using simple tx code path");
> +#ifdef RTE_IXGBE_INC_VECTOR
> +		if (txq->tx_rs_thresh <= RTE_IXGBE_TX_MAX_FREE_BUF_SZ &&
> +					ixgbe_txq_vec_setup(txq) == 0) {

Can process type check been add here and removed from ixgbe_txq_vec_setup()?

Because:
	1. set_tx_function() is better to be process type sensitive, it maybe called from all type process.
	2. ixgbe_txq_vec_setup() can keep runs in primary( remove process type check), also we only need to touch three files instead of four :)

Thanks,
Michael

> +			PMD_INIT_LOG(INFO, "Vector tx enabled.");
> +			dev->tx_pkt_burst = ixgbe_xmit_pkts_vec;
> +		}
> +		else
> +#endif
> +		dev->tx_pkt_burst = ixgbe_xmit_pkts_simple;
> +	} else {
> +		PMD_INIT_LOG(INFO, "Using full-featured tx code path");
> +		PMD_INIT_LOG(INFO,
> +				" - txq_flags = %lx " "[IXGBE_SIMPLE_FLAGS=%lx]",
> +				(long unsigned )txq->txq_flags,
> +				(long unsigned)IXGBE_SIMPLE_FLAGS);
> +		PMD_INIT_LOG(INFO,
> +				" - tx_rs_thresh = %lu " "[RTE_PMD_IXGBE_TX_MAX_BURST=%lu]",
> +				(long unsigned )txq->tx_rs_thresh,
> +				(long unsigned)RTE_PMD_IXGBE_TX_MAX_BURST);
> +		dev->tx_pkt_burst = ixgbe_xmit_pkts;
> +	}
> +}
> +
>  int
>  ixgbe_dev_tx_queue_setup(struct rte_eth_dev *dev,
>  			 uint16_t queue_idx,
> @@ -1933,31 +1967,8 @@ ixgbe_dev_tx_queue_setup(struct rte_eth_dev *dev,
>  	PMD_INIT_LOG(DEBUG, "sw_ring=%p hw_ring=%p dma_addr=0x%"PRIx64,
>  		     txq->sw_ring, txq->tx_ring, txq->tx_ring_phys_addr);
>  
> -	/* Use a simple Tx queue (no offloads, no multi segs) if possible */
> -	if (((txq->txq_flags & IXGBE_SIMPLE_FLAGS) == IXGBE_SIMPLE_FLAGS) &&
> -	    (txq->tx_rs_thresh >= RTE_PMD_IXGBE_TX_MAX_BURST)) {
> -		PMD_INIT_LOG(INFO, "Using simple tx code path");
> -#ifdef RTE_IXGBE_INC_VECTOR
> -		if (txq->tx_rs_thresh <= RTE_IXGBE_TX_MAX_FREE_BUF_SZ &&
> -		    ixgbe_txq_vec_setup(txq) == 0) {
> -			PMD_INIT_LOG(INFO, "Vector tx enabled.");
> -			dev->tx_pkt_burst = ixgbe_xmit_pkts_vec;
> -		}
> -		else
> -#endif
> -			dev->tx_pkt_burst = ixgbe_xmit_pkts_simple;
> -	} else {
> -		PMD_INIT_LOG(INFO, "Using full-featured tx code path");
> -		PMD_INIT_LOG(INFO, " - txq_flags = %lx "
> -			     "[IXGBE_SIMPLE_FLAGS=%lx]",
> -			     (long unsigned)txq->txq_flags,
> -			     (long unsigned)IXGBE_SIMPLE_FLAGS);
> -		PMD_INIT_LOG(INFO, " - tx_rs_thresh = %lu "
> -			     "[RTE_PMD_IXGBE_TX_MAX_BURST=%lu]",
> -			     (long unsigned)txq->tx_rs_thresh,
> -			     (long unsigned)RTE_PMD_IXGBE_TX_MAX_BURST);
> -		dev->tx_pkt_burst = ixgbe_xmit_pkts;
> -	}
> +	/* set up vector or scalar TX function as appropriate */
> +	set_tx_function(dev, txq);
>  
>  	txq->ops->reset(txq);
>  
> diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx.h b/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> index 13099af..873656d 100644
> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> @@ -248,6 +248,13 @@ struct ixgbe_txq_ops {
>  			 IXGBE_ADVTXD_DCMD_DEXT |\
>  			 IXGBE_ADVTXD_DCMD_EOP)
>  
> +
> +/* takes an ethdev and a queue and sets up the tx function to be used based on
> + * the queue parameters. Used in tx_queue_setup by primary process and then
> + * in dev_init by secondary process when attaching to an existing ethdev
> + */
> +void set_tx_function(struct rte_eth_dev* dev, struct igb_tx_queue* txq);
> +
>  #ifdef RTE_IXGBE_INC_VECTOR
>  uint16_t ixgbe_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
>  		uint16_t nb_pkts);
> diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c b/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c
> index 579bc46..6755fad 100644
> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c
> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c
> @@ -748,6 +748,9 @@ int ixgbe_txq_vec_setup(struct igb_tx_queue *txq)
>  	if (txq->sw_ring == NULL)
>  		return -1;
>  
> +	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
> +		return 0;
> +
>  	/* leave the first one for overflow */
>  	txq->sw_ring = (struct igb_tx_entry *)
>  		((struct igb_tx_entry_v *)txq->sw_ring + 1);