Jolynn Schmidt wrote: > Hi, we have some applications that receive very high packet rates, and > have not noticed the behavior I would expect from NAPI (as I > understand it). Does the e1000e driver support napi? If so, wouldn't I > see the number of interrupts (as measured with sar) go down with a > high packet rate (say, >100k). Right now, with interrupt moderation > off for the card I'm seeing virtually 1:1 wrt packets and interrupts. > > Thanks > -- > To unsubscribe from this list: send the line "unsubscribe linux-net" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > According to Intel's documentation it is supported, but here are the details for your perusal: http://downloadmirror.intel.com/15817/eng/README.txt How did you load the module? The documentation is very specific above, and it reads as follows: 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. NOTE: When e1000e 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 e1000e 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. -- To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
