Improve performance of dpdk-vhost driver

  By setting the flag in used table, guest is
  prevented from kicking the host when it adds
  buffers. This results in 100% performance improvement
  when tested throughput using iperf3.

Change-Id: Iefaf5b97d1444c216bb373998732a437d333d521
Signed-off-by: Shesha Sreenivasamurthy <shesha@cisco.com>

diff --git a/vnet/vnet/devices/dpdk/vhost_user.c b/vnet/vnet/devices/dpdk/vhost_user.c
index 2ebf48a..c82b37f 100644 (file)
--- a/vnet/vnet/devices/dpdk/vhost_user.c
+++ b/vnet/vnet/devices/dpdk/vhost_user.c
@@ -589,6 +589,15 @@ dpdk_vhost_user_set_vring_addr(u32 hw_if_index, u8 idx, u64 desc, \
     clib_warning("falied to set vring addr");
   }
 
+  /*
+   * Inform the guest that there is no need to inform (kick) the
+   * host when it adds buffers. kick results in vmexit and will
+   * incur performance degradation.
+   *
+   * The below function sets a flag in used table. Therefore,
+   * should be initialized after initializing vq->used.
+   */
+  rte_vhost_enable_guest_notification(&xd->vu_vhost_dev, idx, 0);
   stop_processing_packets(hw_if_index, idx);
 
   return 0;