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net/netvsc: allow setting Rx and Tx copy break

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The values for Rx and Tx copy break should be tunable rather
than hard coded constants.

The rx_copybreak sets the threshold where the driver uses an
external mbuf to avoid having to copy data. Setting 0 for copybreak
will cause driver to always create an external mbuf. Setting
a value greater than the MTU would prevent it from ever making
an external mbuf and always copy. The default value is 256 (bytes).

Likewise the tx_copybreak sets the threshold where the driver
aggregates multiple small packets into one request. If tx_copybreak
is 0 then each packet goes as a VMBus request (no copying).
If tx_copybreak is set larger than the MTU, then all packets smaller
than the chunk size of the VMBus send buffer will be copied; larger
packets always have to go as a single direct request. The default
value is 512 (bytes).

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Long Li <longli@microsoft.com>
This commit is contained in:
Stephen Hemminger 2020-10-30 17:24:08 -07:00 committed by Ferruh Yigit
parent 364eb0e466
commit 74a5a6663b
4 changed files with 58 additions and 19 deletions
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17
doc/guides/nics/netvsc.rst
View File

@ -116,3 +116,20 @@ The user can specify below argument in devargs.
values save CPU cycles. This parameter is in microseconds.
If the value is too large or too small it will be
ignored by the host. (Default: 50)
#. ``rx_copybreak``:
The rx_copybreak sets the threshold where the driver uses an external
mbuf to avoid having to copy data. Setting 0 for copybreak will cause
driver to always create an external mbuf. Setting a value greater than
the MTU would prevent it from ever making an external mbuf and always
copy. The default value is 256 (bytes).
#. ``tx_copybreak``:
The tx_copybreak sets the threshold where the driver aggregates
multiple small packets into one request. If tx_copybreak is 0 then
each packet goes as a VMBus request (no copying). If tx_copybreak is
set larger than the MTU, then all packets smaller than the chunk size
of the VMBus send buffer will be copied; larger packets always have to
go as a single direct request. The default value is 512 (bytes).

47
drivers/net/netvsc/hn_ethdev.c
View File

@ -45,6 +45,10 @@
DEV_RX_OFFLOAD_VLAN_STRIP | \
DEV_RX_OFFLOAD_RSS_HASH)
#define NETVSC_ARG_LATENCY "latency"
#define NETVSC_ARG_RXBREAK "rx_copybreak"
#define NETVSC_ARG_TXBREAK "tx_copybreak"
struct hn_xstats_name_off {
char name[RTE_ETH_XSTATS_NAME_SIZE];
unsigned int offset;
@ -136,24 +140,32 @@ eth_dev_vmbus_release(struct rte_eth_dev *eth_dev)
eth_dev->intr_handle = NULL;
}
/* handle "latency=X" from devargs */
static int hn_set_latency(const char *key, const char *value, void *opaque)
static int hn_set_parameter(const char *key, const char *value, void *opaque)
{
struct hn_data *hv = opaque;
char *endp = NULL;
unsigned long lat;
errno = 0;
lat = strtoul(value, &endp, 0);
unsigned long v;
v = strtoul(value, &endp, 0);
if (*value == '\0' || *endp != '\0') {
PMD_DRV_LOG(ERR, "invalid parameter %s=%s", key, value);
return -EINVAL;
}
PMD_DRV_LOG(DEBUG, "set latency %lu usec", lat);
if (!strcmp(key, NETVSC_ARG_LATENCY)) {
/* usec to nsec */
hv->latency = v * 1000;
PMD_DRV_LOG(DEBUG, "set latency %u usec", hv->latency);
} else if (!strcmp(key, NETVSC_ARG_RXBREAK)) {
hv->rx_copybreak = v;
PMD_DRV_LOG(DEBUG, "rx copy break set to %u",
hv->rx_copybreak);
} else if (!strcmp(key, NETVSC_ARG_TXBREAK)) {
hv->tx_copybreak = v;
PMD_DRV_LOG(DEBUG, "tx copy break set to %u",
hv->tx_copybreak);
}
hv->latency = lat * 1000; /* usec to nsec */
return 0;
}
@ -163,7 +175,9 @@ static int hn_parse_args(const struct rte_eth_dev *dev)
struct hn_data *hv = dev->data->dev_private;
struct rte_devargs *devargs = dev->device->devargs;
static const char * const valid_keys[] = {
"latency",
NETVSC_ARG_LATENCY,
NETVSC_ARG_RXBREAK,
NETVSC_ARG_TXBREAK,
NULL
};
struct rte_kvargs *kvlist;
@ -177,15 +191,13 @@ static int hn_parse_args(const struct rte_eth_dev *dev)
kvlist = rte_kvargs_parse(devargs->args, valid_keys);
if (!kvlist) {
PMD_DRV_LOG(NOTICE, "invalid parameters");
PMD_DRV_LOG(ERR, "invalid parameters");
return -EINVAL;
}
ret = rte_kvargs_process(kvlist, "latency", hn_set_latency, hv);
if (ret)
PMD_DRV_LOG(ERR, "Unable to process latency arg\n");
ret = rte_kvargs_process(kvlist, NULL, hn_set_parameter, hv);
rte_kvargs_free(kvlist);
return ret;
}
@ -966,7 +978,10 @@ eth_hn_dev_init(struct rte_eth_dev *eth_dev)
hv->chim_res = &vmbus->resource[HV_SEND_BUF_MAP];
hv->port_id = eth_dev->data->port_id;
hv->latency = HN_CHAN_LATENCY_NS;
hv->rx_copybreak = HN_RXCOPY_THRESHOLD;
hv->tx_copybreak = HN_TXCOPY_THRESHOLD;
hv->max_queues = 1;
rte_rwlock_init(&hv->vf_lock);
hv->vf_port = HN_INVALID_PORT;
@ -1122,3 +1137,7 @@ RTE_PMD_REGISTER_VMBUS(net_netvsc, rte_netvsc_pmd);
RTE_PMD_REGISTER_KMOD_DEP(net_netvsc, "* uio_hv_generic");
RTE_LOG_REGISTER(hn_logtype_init, pmd.net.netvsc.init, NOTICE);
RTE_LOG_REGISTER(hn_logtype_driver, pmd.net.netvsc.driver, NOTICE);
RTE_PMD_REGISTER_PARAM_STRING(net_netvsc,
NETVSC_ARG_LATENCY "=<uint32> "
NETVSC_ARG_RXBREAK "=<uint32> "
NETVSC_ARG_TXBREAK "=<uint32>");

8
drivers/net/netvsc/hn_rxtx.c
View File

@ -40,9 +40,6 @@
(sizeof(struct vmbus_chanpkt_hdr) + sizeof(struct hn_nvs_rndis))
#define HN_TXD_CACHE_SIZE 32 /* per cpu tx_descriptor pool cache */
#define HN_TXCOPY_THRESHOLD 512
#define HN_RXCOPY_THRESHOLD 256
#define HN_RXQ_EVENT_DEFAULT 2048
struct hn_rxinfo {
@ -573,7 +570,7 @@ static void hn_rxpkt(struct hn_rx_queue *rxq, struct hn_rx_bufinfo *rxb,
* For large packets, avoid copy if possible but need to keep
* some space available in receive area for later packets.
*/
if (dlen >= HN_RXCOPY_THRESHOLD &&
if (dlen > hv->rx_copybreak &&
(uint32_t)rte_atomic32_read(&rxq->rxbuf_outstanding) <
hv->rxbuf_section_cnt / 2) {
struct rte_mbuf_ext_shared_info *shinfo;
@ -1517,7 +1514,8 @@ hn_xmit_pkts(void *ptxq, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
break;
/* For small packets aggregate them in chimney buffer */
if (m->pkt_len < HN_TXCOPY_THRESHOLD && pkt_size <= txq->agg_szmax) {
if (m->pkt_len <= hv->tx_copybreak &&
pkt_size <= txq->agg_szmax) {
/* If this packet will not fit, then flush */
if (txq->agg_pktleft == 0 ||
RTE_ALIGN(pkt_size, txq->agg_align) > txq->agg_szleft) {

5
drivers/net/netvsc/hn_var.h
View File

@ -23,6 +23,9 @@
/* Host monitor interval */
#define HN_CHAN_LATENCY_NS 50000
#define HN_TXCOPY_THRESHOLD 512
#define HN_RXCOPY_THRESHOLD 256
/* Buffers need to be aligned */
#ifndef PAGE_SIZE
#define PAGE_SIZE 4096
@ -116,6 +119,7 @@ struct hn_data {
struct rte_mem_resource *rxbuf_res; /* UIO resource for Rx */
uint32_t rxbuf_section_cnt; /* # of Rx sections */
uint32_t rx_copybreak;
uint16_t max_queues; /* Max available queues */
uint16_t num_queues;
uint64_t rss_offloads;
@ -124,6 +128,7 @@ struct hn_data {
struct rte_mem_resource *chim_res; /* UIO resource for Tx */
struct rte_bitmap *chim_bmap; /* Send buffer map */
void *chim_bmem;
uint32_t tx_copybreak;
uint32_t chim_szmax; /* Max size per buffer */
uint32_t chim_cnt; /* Max packets per buffer */