Re: [dpdk-dev] [PATCH 3/4] examples/vhost: remove dequeue zero-copy support

["Xia, Chenbo" <chenbo.xia@intel.com>]

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Tuesday, September 15, 2020 9:36 PM
> To: dev@dpdk.org; Xia, Chenbo <chenbo.xia@intel.com>; Stokes, Ian
> <ian.stokes@intel.com>
> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> Subject: [PATCH 3/4] examples/vhost: remove dequeue zero-copy support
> 
> Dequeue zero-copy feature is being removed from the
> Vhost library. This preliminary patch removes its uses
> in the Vhost example application.
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  examples/vhost/main.c | 18 +-----------------
>  1 file changed, 1 insertion(+), 17 deletions(-)
> 
> diff --git a/examples/vhost/main.c b/examples/vhost/main.c
> index e1578e7956..959c0c2838 100644
> --- a/examples/vhost/main.c
> +++ b/examples/vhost/main.c
> @@ -92,7 +92,6 @@ static uint32_t enable_tx_csum;
>  static uint32_t enable_tso;
> 
>  static int client_mode;
> -static int dequeue_zero_copy;
> 
>  static int builtin_net_driver;
> 
> @@ -247,16 +246,6 @@ port_init(uint16_t port)
>  	rx_ring_size = RTE_TEST_RX_DESC_DEFAULT;
>  	tx_ring_size = RTE_TEST_TX_DESC_DEFAULT;
> 
> -	/*
> -	 * When dequeue zero copy is enabled, guest Tx used vring will be
> -	 * updated only when corresponding mbuf is freed. Thus, the
> nb_tx_desc
> -	 * (tx_ring_size here) must be small enough so that the driver will
> -	 * hit the free threshold easily and free mbufs timely. Otherwise,
> -	 * guest Tx vring would be starved.
> -	 */
> -	if (dequeue_zero_copy)
> -		tx_ring_size = 64;
> -
>  	tx_rings = (uint16_t)rte_lcore_count();
> 
>  	/* Get port configuration. */
> @@ -457,8 +446,7 @@ us_vhost_usage(const char *prgname)
>  	"		--socket-file: The path of the socket file.\n"
>  	"		--tx-csum [0|1] disable/enable TX checksum offload.\n"
>  	"		--tso [0|1] disable/enable TCP segment offload.\n"
> -	"		--client register a vhost-user socket as client mode.\n"
> -	"		--dequeue-zero-copy enables dequeue zero copy\n",
> +	"		--client register a vhost-user socket as client mode.\n",
>  	       prgname);
>  }
> 
> @@ -483,7 +471,6 @@ us_vhost_parse_args(int argc, char **argv)
>  		{"tx-csum", required_argument, NULL, 0},
>  		{"tso", required_argument, NULL, 0},
>  		{"client", no_argument, &client_mode, 1},
> -		{"dequeue-zero-copy", no_argument, &dequeue_zero_copy, 1},
>  		{"builtin-net-driver", no_argument, &builtin_net_driver, 1},
>  		{NULL, 0, 0, 0},
>  	};
> @@ -1510,9 +1497,6 @@ main(int argc, char *argv[])
>  	if (client_mode)
>  		flags |= RTE_VHOST_USER_CLIENT;
> 
> -	if (dequeue_zero_copy)
> -		flags |= RTE_VHOST_USER_DEQUEUE_ZERO_COPY;
> -
>  	/* Register vhost user driver to handle vhost messages. */
>  	for (i = 0; i < nb_sockets; i++) {
>  		char *file = socket_files + i * PATH_MAX;
> --
> 2.26.2

Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>