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 78b842ba2d684c7fa16ab208499d8f149f4c9438..148e6a33d6824e6146e66c4cad68c79dae25bb80 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 f7ff8585bc1c77f1fea1e847b7ee7f14eb0c2f33..b3e0a93d45df1dfecfd73de8ad68c0d1a21170fd 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