[ovs-git] [openvswitch/ovs] 29cf9c: userspace: Add TCP Segmentation Offload support
noreply at github.com
Fri Jan 17 23:01:57 UTC 2020
Author: Flavio Leitner <fbl at sysclose.org>
Date: 2020-01-17 (Fri, 17 Jan 2020)
userspace: Add TCP Segmentation Offload support
Abbreviated as TSO, TCP Segmentation Offload is a feature which enables
the network stack to delegate the TCP segmentation to the NIC reducing
the per packet CPU overhead.
A guest using vhostuser interface with TSO enabled can send TCP packets
much bigger than the MTU, which saves CPU cycles normally used to break
the packets down to MTU size and to calculate checksums.
It also saves CPU cycles used to parse multiple packets/headers during
the packet processing inside virtual switch.
If the destination of the packet is another guest in the same host, then
the same big packet can be sent through a vhostuser interface skipping
the segmentation completely. However, if the destination is not local,
the NIC hardware is instructed to do the TCP segmentation and checksum
It is recommended to check if NIC hardware supports TSO before enabling
the feature, which is off by default. For additional information please
check the tso.rst document.
Signed-off-by: Flavio Leitner <fbl at sysclose.org>
Tested-by: Ciara Loftus <ciara.loftus.intel.com>
Signed-off-by: Ian Stokes <ian.stokes at intel.com>
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