Re: [dpdk-dev] [PATCH v1 1/4] example/vhost: add async vhost driver args parsing function

["Jiang, Cheng1" <cheng1.jiang@intel.com>]

Hi Maxime,

Thanks for your comments.
The replies are inline.

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Wednesday, September 23, 2020 4:25 PM
> To: Jiang, Cheng1 <cheng1.jiang@intel.com>; Xia, Chenbo
> <chenbo.xia@intel.com>; Wang, Zhihong <zhihong.wang@intel.com>;
> Mcnamara, John <john.mcnamara@intel.com>; Kovacevic, Marko
> <marko.kovacevic@intel.com>
> Cc: dev@dpdk.org; Fu, Patrick <patrick.fu@intel.com>
> Subject: Re: [PATCH v1 1/4] example/vhost: add async vhost driver args
> parsing function
> 
> 
> 
> On 9/10/20 8:43 AM, Cheng Jiang wrote:
> > This patch is to add async vhost driver arguments parsing function for
> > CBDMA channel. With these arguments vhost sample can be set to use
> > CBDMA or CPU for enqueue operation and bind vhost device with specific
> > CBDMA channel to accelerate vhost data-path.
> >
> > Signed-off-by: Cheng Jiang <Cheng1.jiang@intel.com>
> > ---
> >  examples/vhost/main.c | 133
> > +++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 131 insertions(+), 2 deletions(-)
> >
> > diff --git a/examples/vhost/main.c b/examples/vhost/main.c index
> > e1578e795..011e3da21 100644
> > --- a/examples/vhost/main.c
> > +++ b/examples/vhost/main.c
> > @@ -24,6 +24,9 @@
> >  #include <rte_ip.h>
> >  #include <rte_tcp.h>
> >  #include <rte_pause.h>
> > +#include <rte_rawdev.h>
> > +#include <rte_ioat_rawdev.h>
> > +#include <rte_pci.h>
> >
> >  #include "main.h"
> >
> > @@ -58,6 +61,12 @@
> >  /* Maximum long option length for option parsing. */  #define
> > MAX_LONG_OPT_SZ 64
> >
> > +#define IOAT_RING_SIZE 4096
> > +
> > +#define MAX_ENQUEUED_SIZE 2048
> > +
> > +#define MAX_VHOST_DEVICE 1024
> > +
> >  /* mask of enabled ports */
> >  static uint32_t enabled_port_mask = 0;
> >
> > @@ -96,6 +105,21 @@ static int dequeue_zero_copy;
> >
> >  static int builtin_net_driver;
> >
> > +static int async_vhost_driver;
> > +
> > +struct dma_info {
> > +	struct rte_pci_addr addr;
> > +	uint16_t dev_id;
> > +	bool is_valid;
> > +};
> > +
> > +struct dma_for_vhost {
> > +	struct dma_info dmas[RTE_MAX_QUEUES_PER_PORT * 2];
> > +	uint16_t nr;
> > +};
> > +
> > +static struct dma_for_vhost dma_bind[MAX_VHOST_DEVICE];
> > +
> >  /* Specify timeout (in useconds) between retries on RX. */  static
> > uint32_t burst_rx_delay_time = BURST_RX_WAIT_US;
> >  /* Specify the number of retries on RX. */ @@ -182,6 +206,97 @@
> > struct mbuf_table lcore_tx_queue[RTE_MAX_LCORE];
> >  				 / US_PER_S * BURST_TX_DRAIN_US)
> >  #define VLAN_HLEN       4
> >
> > +static inline int
> > +open_dma(const char *value, void *dma_bind_info) {
> > +	struct dma_for_vhost *dma_info = dma_bind_info;
> > +	char *input = strndup(value, strlen(value) + 1);
> > +	char *addrs = input;
> > +	char *ptrs[2];
> > +	char *start, *end, *substr;
> > +	int64_t vid, vring_id;
> > +	struct rte_ioat_rawdev_config config;
> > +	struct rte_rawdev_info info = { .dev_private = &config };
> > +	char name[32];
> > +	int dev_id;
> > +	int ret = 0;
> > +	uint16_t i = 0;
> > +
> > +	while (isblank(*addrs))
> > +		addrs++;
> > +	if (*addrs == '\0') {
> > +		ret = -1;
> > +		goto out;
> > +	}
> > +
> > +	/* process DMA devices within bracket. */
> > +	addrs++;
> > +	substr = strtok(addrs, ";]");
> > +	if (!substr) {
> > +		ret = -1;
> > +		goto out;
> > +	}
> > +	char *dma_arg[MAX_VHOST_DEVICE];
> > +	rte_strsplit(substr, strlen(substr), dma_arg, MAX_VHOST_DEVICE, ',');
> > +	do {
> > +		char *arg_temp = dma_arg[i];
> > +		rte_strsplit(arg_temp, strlen(arg_temp), ptrs, 2, '@');
> > +
> > +		start = strstr(ptrs[0], "txd");
> > +		if (start == NULL) {
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		start += 3;
> > +		vid = strtol(start, &end, 0);
> > +		if (end == start) {
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		vring_id = 0 + VIRTIO_RXQ;
> > +		if (rte_pci_addr_parse(ptrs[1],
> > +				&(dma_info + vid)->dmas[vring_id].addr) < 0)
> {
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		rte_pci_device_name(&(dma_info + vid)-
> >dmas[vring_id].addr,
> > +				    name, sizeof(name));
> > +		dev_id = rte_rawdev_get_dev_id(name);
> > +		if (dev_id == (uint16_t)(-ENODEV) ||
> > +		    dev_id == (uint16_t)(-EINVAL)) {
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		if (rte_rawdev_info_get(dev_id, &info) < 0 ||
> > +		    strstr(info.driver_name, "ioat") == NULL) {
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		(dma_info + vid)->dmas[vring_id].dev_id = dev_id;
> > +		(dma_info + vid)->dmas[vring_id].is_valid = true;
> > +		config.ring_size = IOAT_RING_SIZE;
> > +		if (rte_rawdev_configure(dev_id, &info) < 0) {
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +		rte_rawdev_start(dev_id);
> > +
> > +		dma_info->nr++;
> > +
> > +		arg_temp = strtok(NULL, ";]");
> > +		i++;
> > +	} while (dma_arg[i]);
> > +
> > +out:
> > +	free(input);
> > +	return ret;
> > +}
> > +
> 
> I think this is purely Intel specifics, so using generic "dma" name is not a good
> idea.
> Also, as this is HW specific, it should be moved to a dedicated file which
> would only be compiled if all dependencies are met. (it does not even build
> on X86:
> http://mails.dpdk.org/archives/test-report/2020-September/151519.html)
> 

I agreed. I'll add another layer of abstraction here, using open_dma function to call the specific DMA initiate function(such as open_ioat) which will be in a dedicated file(ioat.c). And the meson build file will be changed to fix the dependency problem.

> >  /*
> >   * Builds up the correct configuration for VMDQ VLAN pool map
> >   * according to the pool & queue limits.
> > @@ -485,6 +600,8 @@ us_vhost_parse_args(int argc, char **argv)
> >  		{"client", no_argument, &client_mode, 1},
> >  		{"dequeue-zero-copy", no_argument,
> &dequeue_zero_copy, 1},
> >  		{"builtin-net-driver", no_argument, &builtin_net_driver, 1},
> > +		{"async_vhost_driver", no_argument, &async_vhost_driver,
> 1},
> 
> Shouldn't it be in patch 2 where it is used?
> Also, I wonder whether it is really necessary, as as soon as you pass dmas
> parameter you know you'll want to use async mode, no?
> 

Sure I'll fix it in the next version. And as for the necessity of async_vhost_driver, I agree with you. So I'll change it to dma_type to indicate the app that I am going to use what kind of dma for vhost acceleration.

> > +		{"dmas", required_argument, NULL, 0},
> >  		{NULL, 0, 0, 0},
> >  	};
> >
> > @@ -620,13 +737,25 @@ us_vhost_parse_args(int argc, char **argv)
> >  						"socket-file",
> MAX_LONG_OPT_SZ)) {
> >  				if (us_vhost_parse_socket_path(optarg) == -
> 1) {
> >  					RTE_LOG(INFO, VHOST_CONFIG,
> > -					"Invalid argument for socket name
> (Max %d characters)\n",
> > -					PATH_MAX);
> > +						"Invalid argument for socket
> name (Max %d characters)\n",
> > +						PATH_MAX);
> >  					us_vhost_usage(prgname);
> >  					return -1;
> >  				}
> >  			}
> >
> > +			if (!strncmp(long_option[option_index].name,
> > +						"dmas",
> MAX_LONG_OPT_SZ)) {
> > +				if (open_dma(optarg, &dma_bind) == -1) {
> > +					if (*optarg == -1) {
> > +						RTE_LOG(INFO,
> VHOST_CONFIG,
> > +							"Wrong DMA args\n");
> > +						us_vhost_usage(prgname);
> 
> You need to update us_vhost_usage() to document the new arguments.

Sure, I'll do it in the next version.

Thanks,
Cheng

> 
> > +						return -1;
> > +					}
> > +				}
> > +			}
> > +
> >  			break;
> >
> >  			/* Invalid option - print options. */
> >