net/netvsc: set lower host latency

Tune the vmbus connection so the host scans faster. This improves
transmit performance. The host default value is 100us but setting
to 50us reduces packet loss significantly.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>

diff --git a/drivers/net/netvsc/hn_ethdev.c b/drivers/net/netvsc/hn_ethdev.c
index 78b842b..148e6a3 100644 (file)
--- a/drivers/net/netvsc/hn_ethdev.c
+++ b/drivers/net/netvsc/hn_ethdev.c
@@ -264,6 +264,9 @@ static int hn_subchan_configure(struct hn_data *hv,
                        return err;
                }
 
+               rte_vmbus_set_latency(hv->vmbus, new_sc,
+                                     HN_CHAN_LATENCY_NS);
+
                retry = 0;
                chn_index = rte_vmbus_sub_channel_index(new_sc);
                if (chn_index == 0 || chn_index > hv->max_queues) {
@@ -629,6 +632,9 @@ eth_hn_dev_init(struct rte_eth_dev *eth_dev)
        if (err)
                return err;
 
+       rte_vmbus_set_latency(hv->vmbus, hv->channels[0],
+                             HN_CHAN_LATENCY_NS);
+
        hv->primary = hn_rx_queue_alloc(hv, 0,
                                        eth_dev->device->numa_node);
 

diff --git a/drivers/net/netvsc/hn_var.h b/drivers/net/netvsc/hn_var.h
index f7ff858..b3e0a93 100644 (file)
--- a/drivers/net/netvsc/hn_var.h
+++ b/drivers/net/netvsc/hn_var.h
@@ -20,6 +20,9 @@
 /* Retry interval */
 #define HN_CHAN_INTERVAL_US    100
 
+/* Host monitor interval */
+#define HN_CHAN_LATENCY_NS     50000
+
 /* Buffers need to be aligned */
 #ifndef PAGE_SIZE
 #define PAGE_SIZE 4096