Cost of CTPIO

Onload User Guide (UG1586)

Document ID
Release Date
1.2 English

The very low-latency CTPIO transmit path comes at a sacrifice of some of the adapter acceleration features:

The following adapter features are not available to packets sent via CTPIO.

Table 1. Feature Restrictions with CTPIO
Feature Restriction
No checksum offloads Checksums must be done in the host.
No pacing Packet is sent as soon as last descriptor is posted.
No switch loopback No HW loopback of packets to local receivers.
No filter drop No loopback packets to local receivers and CTPIO packets are not subject to any TX drop filters.

No flow control

No Qbb flow control

CTPIO traffic cannot be subject to pause frames or priority flow control measures.

Pause frames received at the CTPIO sender will have no effect.