About guideline of parameters tuning while in polling mode.

[Mao Shou Yan]

Hi, everybody

         Can anyone give some guidelines on tuning the following
parameters when the system is in polling mode and works in high
throughput network environment.

         Thanks a lot!

 

 

/*

 * EM_TIDV - Transmit Interrupt Delay Value 

 * Valid Range: 0-65535 (0=off)

 * Default Value: 64

 *   This value delays the generation of transmit interrupts in units of

 *   1.024 microseconds. Transmit interrupt reduction can improve CPU

 *   efficiency if properly tuned for specific network traffic. If the

 *   system is reporting dropped transmits, this value may be set too
high

 *   causing the driver to run out of available transmit descriptors.

 */

#define EM_TIDV                         64

 

/*

 * EM_TADV - Transmit Absolute Interrupt Delay Value (Not valid for
82542/82543/82544)

 * Valid Range: 0-65535 (0=off)

 * Default Value: 64

 *   This value, in units of 1.024 microseconds, limits the delay in
which a

 *   transmit interrupt is generated. Useful only if EM_TIDV is
non-zero,

 *   this value ensures that an interrupt is generated after the initial

 *   packet is sent on the wire within the set amount of time.  Proper
tuning,

 *   along with EM_TIDV, may improve traffic throughput in specific

 *   network conditions.

 */

#define EM_TADV                         64

 

/*

 * EM_RDTR - Receive Interrupt Delay Timer (Packet Timer) 

 * Valid Range: 0-65535 (0=off)

 * Default Value: 0

 *   This value delays the generation of receive interrupts in units of
1.024

 *   microseconds.  Receive interrupt reduction can improve CPU
efficiency if

 *   properly tuned for specific network traffic. Increasing this value
adds

 *   extra latency to frame reception and can end up decreasing the
throughput

 *   of TCP traffic. If the system is reporting dropped receives, this
value

 *   may be set too high, causing the driver to run out of available
receive

 *   descriptors.

 *

 *   CAUTION: When setting EM_RDTR to a value other than 0, adapters

 *            may hang (stop transmitting) under certain network
conditions.

 *            If this occurs a WATCHDOG message is logged in the system
event log.

 *            In addition, the controller is automatically reset,
restoring the

 *            network connection. To eliminate the potential for the
hang

 *            ensure that EM_RDTR is set to 0.

 */

#define EM_RDTR                         0

 

/*

 * Receive Interrupt Absolute Delay Timer (Not valid for
82542/82543/82544)

 * Valid Range: 0-65535 (0=off)

 * Default Value: 64

 *   This value, in units of 1.024 microseconds, limits the delay in
which a

 *   receive interrupt is generated. Useful only if EM_RDTR is non-zero,

 *   this value ensures that an interrupt is generated after the initial

 *   packet is received within the set amount of time.  Proper tuning,

 *   along with EM_RDTR, may improve traffic throughput in specific
network

 *   conditions.

 */

#define EM_RADV                         64