linuxdebug/Documentation/networking/device_drivers/ethernet/neterion/s2io.rst

.. SPDX-License-Identifier: GPL-2.0

=========================================================
Neterion's (Formerly S2io) Xframe I/II PCI-X 10GbE driver
=========================================================

Release notes for Neterion's (Formerly S2io) Xframe I/II PCI-X 10GbE driver.

.. Contents
  - 1.  Introduction
  - 2.  Identifying the adapter/interface
  - 3.  Features supported
  - 4.  Command line parameters
  - 5.  Performance suggestions
  - 6.  Available Downloads


1. Introduction
===============
This Linux driver supports Neterion's Xframe I PCI-X 1.0 and
Xframe II PCI-X 2.0 adapters. It supports several features
such as jumbo frames, MSI/MSI-X, checksum offloads, TSO, UFO and so on.
See below for complete list of features.

All features are supported for both IPv4 and IPv6.

2. Identifying the adapter/interface
====================================

a. Insert the adapter(s) in your system.
b. Build and load driver::

	# insmod s2io.ko

c. View log messages::

	# dmesg | tail -40

You will see messages similar to::

	eth3: Neterion Xframe I 10GbE adapter (rev 3), Version 2.0.9.1, Intr type INTA
	eth4: Neterion Xframe II 10GbE adapter (rev 2), Version 2.0.9.1, Intr type INTA
	eth4: Device is on 64 bit 133MHz PCIX(M1) bus

The above messages identify the adapter type(Xframe I/II), adapter revision,
driver version, interface name(eth3, eth4), Interrupt type(INTA, MSI, MSI-X).
In case of Xframe II, the PCI/PCI-X bus width and frequency are displayed
as well.

To associate an interface with a physical adapter use "ethtool -p <ethX>".
The corresponding adapter's LED will blink multiple times.

3. Features supported
=====================
a. Jumbo frames. Xframe I/II supports MTU up to 9600 bytes,
   modifiable using ip command.

b. Offloads. Supports checksum offload(TCP/UDP/IP) on transmit
   and receive, TSO.

c. Multi-buffer receive mode. Scattering of packet across multiple
   buffers. Currently driver supports 2-buffer mode which yields
   significant performance improvement on certain platforms(SGI Altix,
   IBM xSeries).

d. MSI/MSI-X. Can be enabled on platforms which support this feature
   (IA64, Xeon) resulting in noticeable performance improvement(up to 7%
   on certain platforms).

e. Statistics. Comprehensive MAC-level and software statistics displayed
   using "ethtool -S" option.

f. Multi-FIFO/Ring. Supports up to 8 transmit queues and receive rings,
   with multiple steering options.

4. Command line parameters
==========================

a. tx_fifo_num
	Number of transmit queues

Valid range: 1-8

Default: 1

b. rx_ring_num
	Number of receive rings

Valid range: 1-8

Default: 1

c. tx_fifo_len
	Size of each transmit queue

Valid range: Total length of all queues should not exceed 8192

Default: 4096

d. rx_ring_sz
	Size of each receive ring(in 4K blocks)

Valid range: Limited by memory on system

Default: 30

e. intr_type
	Specifies interrupt type. Possible values 0(INTA), 2(MSI-X)

Valid values: 0, 2

Default: 2

5. Performance suggestions
==========================

General:

a. Set MTU to maximum(9000 for switch setup, 9600 in back-to-back configuration)
b. Set TCP windows size to optimal value.

For instance, for MTU=1500 a value of 210K has been observed to result in
good performance::

	# sysctl -w net.ipv4.tcp_rmem="210000 210000 210000"
	# sysctl -w net.ipv4.tcp_wmem="210000 210000 210000"

For MTU=9000, TCP window size of 10 MB is recommended::

	# sysctl -w net.ipv4.tcp_rmem="10000000 10000000 10000000"
	# sysctl -w net.ipv4.tcp_wmem="10000000 10000000 10000000"

Transmit performance:

a. By default, the driver respects BIOS settings for PCI bus parameters.
   However, you may want to experiment with PCI bus parameters
   max-split-transactions(MOST) and MMRBC (use setpci command).

   A MOST value of 2 has been found optimal for Opterons and 3 for Itanium.

   It could be different for your hardware.

   Set MMRBC to 4K**.

   For example you can set

   For opteron::

	#setpci -d 17d5:* 62=1d

   For Itanium::

	#setpci -d 17d5:* 62=3d

   For detailed description of the PCI registers, please see Xframe User Guide.

b. Ensure Transmit Checksum offload is enabled. Use ethtool to set/verify this
   parameter.

c. Turn on TSO(using "ethtool -K")::

	# ethtool -K <ethX> tso on

Receive performance:

a. By default, the driver respects BIOS settings for PCI bus parameters.
   However, you may want to set PCI latency timer to 248::

	#setpci -d 17d5:* LATENCY_TIMER=f8

   For detailed description of the PCI registers, please see Xframe User Guide.

b. Use 2-buffer mode. This results in large performance boost on
   certain platforms(eg. SGI Altix, IBM xSeries).

c. Ensure Receive Checksum offload is enabled. Use "ethtool -K ethX" command to
   set/verify this option.

d. Enable NAPI feature(in kernel configuration Device Drivers ---> Network
   device support --->  Ethernet (10000 Mbit) ---> S2IO 10Gbe Xframe NIC) to
   bring down CPU utilization.

.. note::

   For AMD opteron platforms with 8131 chipset, MMRBC=1 and MOST=1 are
   recommended as safe parameters.

For more information, please review the AMD8131 errata at
http://vip.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/
26310_AMD-8131_HyperTransport_PCI-X_Tunnel_Revision_Guide_rev_3_18.pdf

6. Support
==========

For further support please contact either your 10GbE Xframe NIC vendor (IBM,
HP, SGI etc.)