-Valid Range: 100-100000 (0=off, 1=dynamic)
-Default Value: 8000
- This value represents the maximum number of interrupts per second the
- controller generates. InterruptThrottleRate is another setting used in
- interrupt moderation. Dynamic mode uses a heuristic algorithm to adjust
- InterruptThrottleRate based on the current traffic load.
-Un-supported Adapters: InterruptThrottleRate is NOT supported by 82542, 82543
- or 82544-based adapters.
-
- NOTE: InterruptThrottleRate takes precedence over the TxAbsIntDelay and
- RxAbsIntDelay parameters. In other words, minimizing the receive
- and/or transmit absolute delays does not force the controller to
- generate more interrupts than what the Interrupt Throttle Rate
- allows.
- CAUTION: If you are using the Intel PRO/1000 CT Network Connection
- (controller 82547), setting InterruptThrottleRate to a value
- greater than 75,000, may hang (stop transmitting) adapters under
- certain network conditions. If this occurs a NETDEV 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 InterruptThrottleRate is set no greater than 75,000 and is
- not set to 0.
- NOTE: When e1000 is loaded with default settings and multiple adapters are
- in use simultaneously, the CPU utilization may increase non-linearly.
- In order to limit the CPU utilization without impacting the overall
- throughput, we recommend that you load the driver as follows:
-
- insmod e1000.o InterruptThrottleRate=3000,3000,3000
-
- This sets the InterruptThrottleRate to 3000 interrupts/sec for the
- first, second, and third instances of the driver. The range of 2000 to
- 3000 interrupts per second works on a majority of systems and is a
- good starting point, but the optimal value will be platform-specific.
- If CPU utilization is not a concern, use RX_POLLING (NAPI) and default
- driver settings.
+---------------------
+(not supported on Intel(R) 82542, 82543 or 82544-based adapters)
+Valid Range: 0,1,3,100-100000 (0=off, 1=dynamic, 3=dynamic conservative)
+Default Value: 3
+
+The driver can limit the amount of interrupts per second that the adapter
+will generate for incoming packets. It does this by writing a value to the
+adapter that is based on the maximum amount of interrupts that the adapter
+will generate per second.
+
+Setting InterruptThrottleRate to a value greater or equal to 100
+will program the adapter to send out a maximum of that many interrupts
+per second, even if more packets have come in. This reduces interrupt
+load on the system and can lower CPU utilization under heavy load,
+but will increase latency as packets are not processed as quickly.
+
+The default behaviour of the driver previously assumed a static
+InterruptThrottleRate value of 8000, providing a good fallback value for
+all traffic types,but lacking in small packet performance and latency.
+The hardware can handle many more small packets per second however, and
+for this reason an adaptive interrupt moderation algorithm was implemented.
+
+Since 7.3.x, the driver has two adaptive modes (setting 1 or 3) in which
+it dynamically adjusts the InterruptThrottleRate value based on the traffic
+that it receives. After determining the type of incoming traffic in the last
+timeframe, it will adjust the InterruptThrottleRate to an appropriate value
+for that traffic.
+
+The algorithm classifies the incoming traffic every interval into
+classes. Once the class is determined, the InterruptThrottleRate value is
+adjusted to suit that traffic type the best. There are three classes defined:
+"Bulk traffic", for large amounts of packets of normal size; "Low latency",
+for small amounts of traffic and/or a significant percentage of small
+packets; and "Lowest latency", for almost completely small packets or
+minimal traffic.
+
+In dynamic conservative mode, the InterruptThrottleRate value is set to 4000
+for traffic that falls in class "Bulk traffic". If traffic falls in the "Low
+latency" or "Lowest latency" class, the InterruptThrottleRate is increased
+stepwise to 20000. This default mode is suitable for most applications.
+
+For situations where low latency is vital such as cluster or
+grid computing, the algorithm can reduce latency even more when
+InterruptThrottleRate is set to mode 1. In this mode, which operates
+the same as mode 3, the InterruptThrottleRate will be increased stepwise to
+70000 for traffic in class "Lowest latency".
+
+Setting InterruptThrottleRate to 0 turns off any interrupt moderation
+and may improve small packet latency, but is generally not suitable
+for bulk throughput traffic.
+
+NOTE: InterruptThrottleRate takes precedence over the TxAbsIntDelay and
+ RxAbsIntDelay parameters. In other words, minimizing the receive
+ and/or transmit absolute delays does not force the controller to
+ generate more interrupts than what the Interrupt Throttle Rate
+ allows.
+
+CAUTION: If you are using the Intel(R) PRO/1000 CT Network Connection
+ (controller 82547), setting InterruptThrottleRate to a value
+ greater than 75,000, may hang (stop transmitting) adapters
+ under certain network conditions. If this occurs a NETDEV
+ 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 InterruptThrottleRate is set no greater
+ than 75,000 and is not set to 0.
+
+NOTE: When e1000 is loaded with default settings and multiple adapters
+ are in use simultaneously, the CPU utilization may increase non-
+ linearly. In order to limit the CPU utilization without impacting
+ the overall throughput, we recommend that you load the driver as
+ follows:
+
+ modprobe e1000 InterruptThrottleRate=3000,3000,3000
+
+ This sets the InterruptThrottleRate to 3000 interrupts/sec for
+ the first, second, and third instances of the driver. The range
+ of 2000 to 3000 interrupts per second works on a majority of
+ systems and is a good starting point, but the optimal value will
+ be platform-specific. If CPU utilization is not a concern, use
+ RX_POLLING (NAPI) and default driver settings.
+
+