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Intelligent NIC Installation and Tuning Guide
NetXen, Inc.
Appendix A. Tuning Guidelines
-m <mapping> [mapping]
where a mapping is a session(s),processor,receiver IP set
e.g. -m 4,0,1.2.3.4 sets up:
4 sessions on processor 0 to test a network on 1.2.3.4
A.2
Windows Optimization — Tcp1323Opts
This parameter determines whether TCP uses the time-stamping and window scaling
features described in
RFC 1323, TCP Extensions for High Performance
.
Window scaling permits TCP to negotiate a scaling factor for the TCP receive window
size, allowing for a very large TCP receive window of up to 1 Gbyte. The TCP receive
window is the amount of data the sending host can send at one time on a connection.
To set the window scaling and timestamp parameters, click Start -> Run, then type
regedit
to start the registry editor. Open the following location:
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Window Scaling
For more efficient use of high bandwidth networks, a larger TCP window size may be
used. The TCP window size field controls the flow of data and is limited to 2 bytes, or a
window size of 65,535 bytes.
Since the size field cannot be expanded, a scaling factor is used. TCP window scale is an
option used to increase the maximum window size from 65,535 bytes to 1 Gigabyte.
When the value for window size is added to the registry and its size is larger than the
default value, Windows attempts to use a scale value that accommodates the new
window size.
A.3
Linux Performance Tools
Once connectivity between the two cards is established, common performance tools can
be used for performance measurements.
Note:
Various factors including tools, kernel, stacks, and related parameters affect the
performance of a system. A discussion on performance criteria is beyond the scope for
the getting started section.
Data Type
Range
Recommended
Value
REG_DWORD
0 | 1 | 2 | 3
1
Hex Value
Meaning
0
Timestamps and window scaling are disabled.
1
Window scaling is enabled.
2
Timestamps are enabled.
3
Timestamps and window scaling are enabled.
