User`s guide

114 XgOS User’s Guide • September 2014
4. Check the flags field for ct where:
t indicates that TSO is configured on the vNIC.
c indicates that checksumming is enabled on the TSO vNIC.
Receive Batching
Virtual NICs support Receive Batching (also called receive packet coalescing). This
feature allows numerous small packets coming from the network to be bundled
together into fewer and larger frames as they travel over the vNIC. On the 10 GE or
10-Port GE module where the vNIC is terminated, the smaller frames are merged
together and sent to the host server. By reducing the amount of packets that are
received, the host has fewer CPUs operations to perform in order to process the
packets. Receive Batching increases the network throughput and lessens host CPU
utilization by reducing the number of packets that the host receives. Receive
Batching is considered from the perspective of the host server, so it applies to traffic
that the server is receiving.
Note – Another feature called TCP segmentation offload performs the opposite
function (segmenting large packets) for traffic that the host server is transmitting.
Both Receive Batching and TCP segmentation offload can be configured on the same
vNIC if your host(s) need performance optimization for both directions of traffic. For
information, see “TCP Segmentation Offload” on page 111.
Receive batching for Linux hosts is supported for packets with an MTU less than or
equal to 8192. The Linux host drivers automatically make this delineation, so if a
host is receiving traffic with an MTU greater than 8192, the receive batching feature
is off.
Requirements
■ The following minimum versions of XgOS and host drivers are required to
support Receive Batching:
■ XgOS 3.6.0 or later
■ OVN host driver version 4.2.0 or later
■ For HA vNICs, both the primary and secondary vNIC must be configured with
the same Receive Batching configuration.