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Commit 571de88b authored by Ravinandan Arakali's avatar Ravinandan Arakali Committed by Jeff Garzik
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[PATCH] S2io: Updated documentation



Hi,
This patch provides updated documentation on the Neterion(S2io) driver.

Please review the patch.

Signed-off-by: default avatarRavinandan Arakali <ravinandan.arakali@neterion.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@pobox.com>
parent da6971d8
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S2IO Technologies XFrame 10 Gig adapter.
Release notes for Neterion's (Formerly S2io) Xframe I/II PCI-X 10GbE driver.
-------------------------------------------


Contents
I. Module loadable parameters.
=======
When loaded as a module, the driver provides a host of Module loadable
- 1.  Introduction
parameters, so the device can be tuned as per the users needs.
- 2.  Identifying the adapter/interface
A list of the Module params is given below.
- 3.  Features supported
(i)	ring_num: This can be used to program the number of
- 4.  Command line parameters
		 receive rings used in the driver.
- 5.  Performance suggestions
(ii)	ring_len: This defines the number of descriptors each ring
- 6.  Available Downloads 
		 can have. There can be a maximum of 8 rings.

(iii)	frame_len: This is an array of size 8. Using this we can 

		 set the maximum size of the received frame that can
1.	Introduction:
		 be steered into the corrsponding receive ring.	
This Linux driver supports Neterion's Xframe I PCI-X 1.0 and
(iv)	fifo_num: This defines the number of Tx FIFOs thats used in
Xframe II PCI-X 2.0 adapters. It supports several features 
		 the driver. 
such as jumbo frames, MSI/MSI-X, checksum offloads, TSO, UFO and so on.
(v)	fifo_len: Each element defines the number of 
See below for complete list of features.
 		 Tx descriptors that can be associated with each 
All features are supported for both IPv4 and IPv6.
		 corresponding FIFO. There are a maximum of 8 FIFOs.

(vi)	tx_prio: This is a bool, if module is loaded with a non-zero
2.	Identifying the adapter/interface:
		value for tx_prio multi FIFO scheme is activated.
a. Insert the adapter(s) in your system.
(vii)	rx_prio: This is a bool, if module is loaded with a non-zero
b. Build and load driver 
		value for tx_prio multi RING scheme is activated.
# insmod s2io.ko
(viii)	latency_timer: The value given against this param will be
c. View log messages
		 loaded	into the latency timer register in PCI Config
# dmesg | tail -40
		 space, else the register is left with its reset value.
You will see messages similar to:

eth3: Neterion Xframe I 10GbE adapter (rev 3), Version 2.0.9.1, Intr type INTA
II. Performance tuning.
eth4: Neterion Xframe II 10GbE adapter (rev 2), Version 2.0.9.1, Intr type INTA
 By changing a few sysctl parameters.
eth4: Device is on 64 bit 133MHz PCIX(M1) bus
	Copy the following lines into a file and run the following command,

	"sysctl -p <file_name>"
The above messages identify the adapter type(Xframe I/II), adapter revision,
### IPV4 specific settings
driver version, interface name(eth3, eth4), Interrupt type(INTA, MSI, MSI-X).
net.ipv4.tcp_timestamps = 0 # turns TCP timestamp support off, default 1, reduces CPU use
In case of Xframe II, the PCI/PCI-X bus width and frequency are displayed
net.ipv4.tcp_sack = 0 # turn SACK support off, default on
as well.
# on systems with a VERY fast bus -> memory interface this is the big gainer

net.ipv4.tcp_rmem = 10000000 10000000 10000000 # sets min/default/max TCP read buffer, default 4096 87380 174760
To associate an interface with a physical adapter use "ethtool -p <ethX>".
net.ipv4.tcp_wmem = 10000000 10000000 10000000 # sets min/pressure/max TCP write buffer, default 4096 16384 131072
The corresponding adapter's LED will blink multiple times.
net.ipv4.tcp_mem = 10000000 10000000 10000000 # sets min/pressure/max TCP buffer space, default 31744 32256 32768

                                                                                
3.	Features supported:
### CORE settings (mostly for socket and UDP effect)
a. Jumbo frames. Xframe I/II supports MTU upto 9600 bytes,
net.core.rmem_max = 524287 # maximum receive socket buffer size, default 131071
modifiable using ifconfig command.
net.core.wmem_max = 524287 # maximum send socket buffer size, default 131071

net.core.rmem_default = 524287 # default receive socket buffer size, default 65535
b. Offloads. Supports checksum offload(TCP/UDP/IP) on transmit
net.core.wmem_default = 524287 # default send socket buffer size, default 65535
and receive, TSO.
net.core.optmem_max = 524287 # maximum amount of option memory buffers, default 10240

net.core.netdev_max_backlog = 300000 # number of unprocessed input packets before kernel starts dropping them, default 300
c. Multi-buffer receive mode. Scattering of packet across multiple
---End of performance tuning file---
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(upto 7%
on certain platforms).

e. NAPI. Compile-time option(CONFIG_S2IO_NAPI) for better Rx interrupt 
moderation.

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

g. 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 1(INTA), 2(MSI), 3(MSI-X)
Valid range: 1-3
Default: 1 

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
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.

** 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://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/26310.pdf

6.  Available Downloads
Neterion "s2io" driver in Red Hat and Suse 2.6-based distributions is kept up 
to date, also the latest "s2io" code (including support for 2.4 kernels) is 
available via "Support" link on the Neterion site:  http://www.neterion.com.

For Xframe User Guide (Programming manual), visit ftp site ns1.s2io.com,
user: linuxdocs password: HALdocs

7. Support 
For further support please contact either your 10GbE Xframe NIC vendor (IBM, 
HP, SGI etc.) or click on the "Support" link on the Neterion site:  
http://www.neterion.com.