
Issue 11
© Solarflare Communications 2014
224
Solarflare Server Adapter
User Guide
• generate less interrupts
• reduce CPU utilization (because there are less interrupts to process)
• increase latency
• improve peak throughput
Decreasing the interrupt moderation interval will:
• generate more interrupts
• increase CPU utilization (because there are more interrupts to process)
• decrease latency
• reduce peak throughput
TCP/IP Checksum Offload
Checksum offload defers the calculation and verification of IP Header, TCP and UDP packet
checksums to the adapter. The driver has all checksum offload features enabled by default.
Therefore, there is no opportunity to improve performance from the default.
Checksum offload configuration is changed by changing the Offload IP checksum, Offload UDP
checksum and Offload TCP checksum settings in the Network Adapter’s Advanced Properties Page.
Large Send Offload (LSO)
Large Send offload (LSO; also known as TCP Segmentation Offload/TSO) offloads the splitting of
outgoing TCP data into packets to the adapter. LSO benefits applications using TCP. Applications
using protocols other than TCP will not be affected by LSO.
Enabling LSO will reduce CPU utilization on the transmit side of a TCP connection and improve peak
throughput, if the CPU is fully utilized. Since LSO has no affect on latency, it can be enabled at all
times. The driver has LSO enabled by default.
LSO is changed by changing the Large Send Offload setting in the Network Adapter’s Advanced
Properties Page. TCP and IP checksum offloads must be enabled for LSO to work.
NOTE:
Solarflare recommend that you do not disable this setting.