ice: replace custom AIM algorithm with kernel's DIM library
The ice driver has support for adaptive interrupt moderation, an algorithm for tuning the interrupt rate dynamically. This algorithm is based on various assumptions about ring size, socket buffer size, link speed, SKB overhead, ethernet frame overhead and more. The Linux kernel has support for a dynamic interrupt moderation algorithm known as "dimlib". Replace the custom driver-specific implementation of dynamic interrupt moderation with the kernel's algorithm. The Intel hardware has a different hardware implementation than the originators of the dimlib code had to work with, which requires the driver to use a slightly different set of inputs for the actual moderation values, while getting all the advice from dimlib of better/worse, shift left or right. The change made for this implementation is to use a pair of values for each of the 5 "slots" that the dimlib moderation expects, and the driver will program those pairs when dimlib recommends a slot to use. The currently implementation uses two tables, one for receive and one for transmit, and the pairs of values in each slot set the maximum delay of an interrupt and a maximum number of interrupts per second (both expressed in microseconds). There are two separate kinds of bugs fixed by using DIMLIB, one is UDP single stream send was too slow, and the other is that 8K ping-pong was going to the most aggressive moderation and has much too high latency. The overall result of using DIMLIB is that we meet or exceed our performance expectations set based on the old algorithm. Co-developed-by: Jesse Brandeburg <jesse.brandeburg@intel.com> Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com> Tested-by: Tony Brelinski <tonyx.brelinski@intel.com> Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
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