Re: [dpdk-dev] [PATCH 2/2] examples/vhost: use factorized default Rx/Tx configuration

["Chen, Jing D" <jing.d.chen@intel.com>]

Hi,

> -----Original Message-----
> From: Xie, Huawei
> Sent: Thursday, November 13, 2014 6:34 AM
> To: dev@dpdk.org
> Cc: Chen, Jing D; Xie, Huawei
> Subject: [PATCH 2/2] examples/vhost: use factorized default Rx/Tx
> configuration
> 
> Refer to Pablo's commit:
>     "use factorized default Rx/Tx configuration
> 
>     For apps that were using default rte_eth_rxconf and rte_eth_txconf
>     structures, these have been removed and now they are obtained by
>     calling rte_eth_dev_info_get, just before setting up RX/TX queues."
> 
> move zero copy's deferred start set up ahead.
> 
> Signed-off-by: Huawei Xie <huawei.xie@intel.com>
> ---
>  examples/vhost/main.c | 78 +++++++++++++++----------------------------------
> --
>  1 file changed, 22 insertions(+), 56 deletions(-)
> 
> diff --git a/examples/vhost/main.c b/examples/vhost/main.c
> index 2b1bf02..fa36913 100644
> --- a/examples/vhost/main.c
> +++ b/examples/vhost/main.c
> @@ -79,25 +79,6 @@
>  	+ RTE_PKTMBUF_HEADROOM)
>  #define MBUF_CACHE_SIZE_ZCP 0
> 
> -/*
> - * RX and TX Prefetch, Host, and Write-back threshold values should be
> - * carefully set for optimal performance. Consult the network
> - * controller's datasheet and supporting DPDK documentation for guidance
> - * on how these parameters should be set.
> - */
> -#define RX_PTHRESH 8 /* Default values of RX prefetch threshold reg. */
> -#define RX_HTHRESH 8 /* Default values of RX host threshold reg. */
> -#define RX_WTHRESH 4 /* Default values of RX write-back threshold reg. */
> -
> -/*
> - * These default values are optimized for use with the Intel(R) 82599 10 GbE
> - * Controller and the DPDK ixgbe PMD. Consider using other values for other
> - * network controllers and/or network drivers.
> - */
> -#define TX_PTHRESH 36 /* Default values of TX prefetch threshold reg. */
> -#define TX_HTHRESH 0  /* Default values of TX host threshold reg. */
> -#define TX_WTHRESH 0  /* Default values of TX write-back threshold reg. */
> -
>  #define MAX_PKT_BURST 32 		/* Max burst size for RX/TX */
>  #define BURST_TX_DRAIN_US 100 	/* TX drain every ~100us */
> 
> @@ -217,32 +198,6 @@ static uint32_t burst_rx_retry_num =
> BURST_RX_RETRIES;
>  /* Character device basename. Can be set by user. */
>  static char dev_basename[MAX_BASENAME_SZ] = "vhost-net";
> 
> -
> -/* Default configuration for rx and tx thresholds etc. */
> -static struct rte_eth_rxconf rx_conf_default = {
> -	.rx_thresh = {
> -		.pthresh = RX_PTHRESH,
> -		.hthresh = RX_HTHRESH,
> -		.wthresh = RX_WTHRESH,
> -	},
> -	.rx_drop_en = 1,
> -};
> -
> -/*
> - * These default values are optimized for use with the Intel(R) 82599 10 GbE
> - * Controller and the DPDK ixgbe/igb PMD. Consider using other values for
> other
> - * network controllers and/or network drivers.
> - */
> -static struct rte_eth_txconf tx_conf_default = {
> -	.tx_thresh = {
> -		.pthresh = TX_PTHRESH,
> -		.hthresh = TX_HTHRESH,
> -		.wthresh = TX_WTHRESH,
> -	},
> -	.tx_free_thresh = 0, /* Use PMD default values */
> -	.tx_rs_thresh = 0, /* Use PMD default values */
> -};
> -
>  /* empty vmdq configuration structure. Filled in programatically */
>  static struct rte_eth_conf vmdq_conf_default = {
>  	.rxmode = {
> @@ -410,7 +365,9 @@ port_init(uint8_t port)
>  {
>  	struct rte_eth_dev_info dev_info;
>  	struct rte_eth_conf port_conf;
> -	uint16_t rx_rings, tx_rings;
> +	struct rte_eth_rxconf *rxconf;
> +	struct rte_eth_txconf *txconf;
> +	int16_t rx_rings, tx_rings;
>  	uint16_t rx_ring_size, tx_ring_size;
>  	int retval;
>  	uint16_t q;
> @@ -418,6 +375,21 @@ port_init(uint8_t port)
>  	/* The max pool number from dev_info will be used to validate the
> pool number specified in cmd line */
>  	rte_eth_dev_info_get (port, &dev_info);
> 
> +	rxconf = &dev_info.default_rxconf;
> +	txconf = &dev_info.default_txconf;
> +	rxconf->rx_drop_en = 1;
> +
> +	/*
> +	 * Zero copy defers queue RX/TX start to the time when guest
> +	 * finishes its startup and packet buffers from that guest are
> +	 * available.
> +	 */
> +	if (zero_copy) {
> +		rxconf->rx_deferred_start = 1;
> +		rxconf->rx_drop_en = 0;
> +		txconf->tx_deferred_start = 1;
> +	}
> +

May I know why 'rx_drop_en' is cleared after 'zero_copy' set?

>  	/*configure the number of supported virtio devices based on VMDQ
> limits */
>  	num_devices = dev_info.max_vmdq_pools;
> 
> @@ -460,14 +432,16 @@ port_init(uint8_t port)
>  	/* Setup the queues. */
>  	for (q = 0; q < rx_rings; q ++) {
>  		retval = rte_eth_rx_queue_setup(port, q, rx_ring_size,
> -						rte_eth_dev_socket_id(port),
> &rx_conf_default,
> +						rte_eth_dev_socket_id(port),
> +						rxconf,
>  						vpool_array[q].pool);
>  		if (retval < 0)
>  			return retval;
>  	}
>  	for (q = 0; q < tx_rings; q ++) {
>  		retval = rte_eth_tx_queue_setup(port, q, tx_ring_size,
> -						rte_eth_dev_socket_id(port),
> &tx_conf_default);
> +						rte_eth_dev_socket_id(port),
> +						txconf);
>  		if (retval < 0)
>  			return retval;
>  	}
> @@ -2920,14 +2894,6 @@ MAIN(int argc, char *argv[])
>  		char pool_name[RTE_MEMPOOL_NAMESIZE];
>  		char ring_name[RTE_MEMPOOL_NAMESIZE];
> 
> -		/*
> -		 * Zero copy defers queue RX/TX start to the time when
> guest
> -		 * finishes its startup and packet buffers from that guest are
> -		 * available.
> -		 */
> -		rx_conf_default.rx_deferred_start = (uint8_t)zero_copy;
> -		rx_conf_default.rx_drop_en = 0;
> -		tx_conf_default.tx_deferred_start = (uint8_t)zero_copy;
>  		nb_mbuf = num_rx_descriptor
>  			+ num_switching_cores * MBUF_CACHE_SIZE_ZCP
>  			+ num_switching_cores * MAX_PKT_BURST;
> --
> 1.8.1.4