
Chapter II. Network (NIC/TOE)
Chelsio T5/T4 Unified Wire For Linux Page 52
4. Software/Driver Configuration and Fine-tuning
4.1. Instantiate Virtual Functions (SR-IOV)
To instantiate the Virtual functions, load the cxgb4 driver with num_vf parameter with a non-zero
value. For example:
[root@host]# modprobe cxgb4 num_vf=1,0,0,0
The number(s) provided for num_vf parameter specifies the number of Virtual Functions to be
instantiated per Physical Function. The Virtual Functions can be assigned to Virtual Machines
(Guests). A maximum of 64 Virtual Functions can be instantiated with 16 Virtual Functions per
Physical Function. Loading the cxgb4 driver with num_vf parameter loads the cxgb4vf module
(the driver for Virtual Functions) in the host by default. Hence unload the cxgb4vf module (on
the host) before assigning Virtual Functions to the Virtual Machines (Guests), using the
following command:
[root@host]# rmmod cxgb4vf
4.2. Performance tuning
In order to auto tune the system and TOE devices for best performance, Chelsio recommends
installing the tools which will copy t4_perftune.sh script to /sbin directory. Run the script by
using the following command:
[root@host]# t4_perftune.sh
This script will configure RSS and enable Interrupt Coalescing.
To get familiar with physical and virtual function terminologies, please refer the
PCI Express specification.
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