rte_pie.h(3)

📦 version 26.03, in nixos 26.05, nixpkgs unstable

💅 rte_pie.h(3) — Library Functions Manual 💅

okay bestie, so this is a page from the Library Functions Manual about rte_pie.h, and no cap, it's giving "networking internals but make it cute." PIE stands for Proportional Integral controller Enhanced, which sounds like a math class you'd skip but actually it's the thing deciding whether your packets get in or get yeeted. let's get into it 🫶

✨ NAME ✨

rte_pie.h — literally just the header. that's the name. iconic minimalism, honestly. 👑

🌸 SYNOPSIS 🌸

#include <stdint.h>
#include <rte_random.h>
#include <rte_debug.h>
#include <rte_cycles.h>

🎀 Data Structures

  • struct rte_pie_params
  • struct rte_pie_config
  • struct rte_pie

🎀 Macros

#define RTE_DQ_THRESHOLD   16384
#define RTE_DQ_WEIGHT   0.25
#define RTE_ALPHA   0.125
#define RTE_BETA   1.25
#define RTE_RAND_MAX   ~0LLU

🎀 Functions

  • int rte_pie_rt_data_init (struct rte_pie *pie) — initialises run-time data.
  • int rte_pie_config_init (struct rte_pie_config *pie_cfg, const uint16_t qdelay_ref, const uint16_t dp_update_interval, const uint16_t max_burst, const uint16_t tailq_th) — configures a single PIE configuration parameter structure.
  • static int rte_pie_enqueue_empty (const struct rte_pie_config *pie_cfg, struct rte_pie *pie, uint32_t pkt_len) — decides packet enqueue when queue is empty.
  • static void _calc_drop_probability (const struct rte_pie_config *pie_cfg, struct rte_pie *pie, uint64_t time) — make a decision to drop or enqueue a packet based on probability criteria.
  • static int _rte_pie_drop (const struct rte_pie_config *pie_cfg, struct rte_pie *pie) — make a decision to drop or enqueue a packet based on probability criteria.
  • static int rte_pie_enqueue_nonempty (const struct rte_pie_config *pie_cfg, struct rte_pie *pie, uint32_t pkt_len, const uint64_t time) — decides if new packet should be enqueued or dropped for non-empty queue.
  • static int rte_pie_enqueue (const struct rte_pie_config *pie_cfg, struct rte_pie *pie, const unsigned int qlen, uint32_t pkt_len, const uint64_t time) — decides if new packet should be enqueued or dropped. updates run time data and gives verdict whether to enqueue or drop the packet.
  • static void rte_pie_dequeue (struct rte_pie *pie, uint32_t pkt_len, uint64_t time) — PIE rate estimation method. called on each packet departure.

🦋 Detailed Description 🦋

Proportional Integral controller Enhanced (PIE) 💖

ok so that's the whole vibe of this file. it's PIE. it controls queues. it's proportional AND integral AND enhanced, which is a lot of adjectives but we respect the hustle.

Definition in file rte_pie.h.

✨ Macro Definition Documentation ✨

🍓 #define RTE_DQ_THRESHOLD 16384

Queue length threshold (2^14) to start measurement cycle (bytes) 📏

Definition at line 23 of file rte_pie.h.

🍓 #define RTE_DQ_WEIGHT 0.25

Weight (RTE_DQ_THRESHOLD/2^16) to compute dequeue rate ⚖️

Definition at line 26 of file rte_pie.h.

🍓 #define RTE_ALPHA 0.125

Weights in drop probability calculations 🎚️

Definition at line 27 of file rte_pie.h.

🍓 #define RTE_BETA 1.25

Weights in drop probability calculations 🎚️ (yes, same description as alpha, they're a matched set, it's giving duo energy)

Definition at line 28 of file rte_pie.h.

🍓 #define RTE_RAND_MAX ~0LLU

Max value of the random number 🎲

Definition at line 29 of file rte_pie.h.

💜 Function Documentation 💜

🌈 int rte_pie_rt_data_init (struct rte_pie * pie)

Initialises run-time data. like setting up the whole personality of your PIE instance before it goes out into the world ✨

Parameters

  • pie [in,out] — data pointer to PIE runtime data

Returns

Operation status

Return values

  • 0 — success 🎉
  • !0 — error 😭

🌈 int rte_pie_config_init (struct rte_pie_config * pie_cfg, const uint16_t qdelay_ref, const uint16_t dp_update_interval, const uint16_t max_burst, const uint16_t tailq_th)

Configures a single PIE configuration parameter structure. this is where you tell PIE how to behave, and it listens, because it's a good little controller 🎀

Parameters

  • pie_cfg [in,out] — config pointer to a PIE configuration parameter structure
  • qdelay_ref [in] — latency target (milliseconds)
  • dp_update_interval [in] — update interval for drop probability (milliseconds)
  • max_burst [in] — maximum burst allowance (milliseconds)
  • tailq_th [in] — tail drop threshold for the queue (number of packets)

Returns

Operation status

Return values

  • 0 — success 🎉
  • !0 — error 😭

🌈 int rte_pie_enqueue_empty (const struct rte_pie_config * pie_cfg, struct rte_pie * pie, uint32_t pkt_len) [static]

Decides packet enqueue when queue is empty. Note: packet is never dropped in this particular case. 😌 empty queue? everybody eats. no drama.

Parameters

  • pie_cfg [in] — config pointer to a PIE configuration parameter structure
  • pie [in, out] — data pointer to PIE runtime data
  • pkt_len [in] — packet length in bytes

Returns

Operation status

Return values

  • 0 — enqueue the packet
  • !0 — drop the packet

If the queue has been idle for a while, turn off PIE and Reset counters 💤

Definition at line 116 of file rte_pie.h.

🌈 void _calc_drop_probability (const struct rte_pie_config * pie_cfg, struct rte_pie * pie, uint64_t time) [static]

make a decision to drop or enqueue a packet based on probability criteria 🎲 this is the "should I be messy right now" function, and the answer is mathematically determined.

Parameters

  • pie_cfg [in] — config pointer to a PIE configuration parameter structure
  • pie [in, out] — data pointer to PIE runtime data
  • time [in] — current time (measured in cpu cycles) ⏱️

Definition at line 147 of file rte_pie.h.

🌈 int _rte_pie_drop (const struct rte_pie_config * pie_cfg, struct rte_pie * pie) [inline], [static]

make a decision to drop or enqueue a packet based on probability criteria 🎲 (same description, different function — they're siblings, it's a whole family)

Parameters

  • pie_cfg [in] — config pointer to a PIE configuration parameter structure
  • pie [in, out] — data pointer to PIE runtime data

Returns

operation status

Return values

  • 0 — enqueue the packet
  • 1 — drop the packet 💀

Definition at line 210 of file rte_pie.h.

🌈 int rte_pie_enqueue_nonempty (const struct rte_pie_config * pie_cfg, struct rte_pie * pie, uint32_t pkt_len, const uint64_t time) [inline], [static]

Decides if new packet should be enqueued or dropped for non-empty queue. now the queue has opinions, and those opinions involve thresholds 🔥

Parameters

  • pie_cfg [in] — config pointer to a PIE configuration parameter structure
  • pie [in,out] — data pointer to PIE runtime data
  • pkt_len [in] — packet length in bytes
  • time [in] — current time (measured in cpu cycles) ⏱️

Returns

Operation status

Return values

  • 0 — enqueue the packet
  • 1 — drop the packet based on max threshold criterion
  • 2 — drop the packet based on mark probability criterion

Definition at line 258 of file rte_pie.h.

🌈 int rte_pie_enqueue (const struct rte_pie_config * pie_cfg, struct rte_pie * pie, const unsigned int qlen, uint32_t pkt_len, const uint64_t time) [inline], [static]

Decides if new packet should be enqueued or dropped. Updates run time data and gives verdict whether to enqueue or drop the packet. the main character function, honestly 👑 it updates its own bookkeeping AND judges you at the same time.

Parameters

  • pie_cfg [in] — config pointer to a PIE configuration parameter structure
  • pie [in,out] — data pointer to PIE runtime data
  • qlen [in] — queue length
  • pkt_len [in] — packet length in bytes
  • time [in] — current time stamp (measured in cpu cycles) ⏱️

Returns

Operation status

Return values

  • 0 — enqueue the packet
  • 1 — drop the packet based on drop probability criteria

Definition at line 325 of file rte_pie.h.

🌈 void rte_pie_dequeue (struct rte_pie * pie, uint32_t pkt_len, uint64_t time) [inline], [static]

PIE rate estimation method. Called on each packet departure. 👋 bye packet! now we do math about how fast you left so we can estimate the rate.

Parameters

  • pie [in] — data pointer to PIE runtime data
  • pkt_len [in] — packet length in bytes
  • time [in] — current time stamp in cpu cycles ⏱️

Definition at line 349 of file rte_pie.h.

🌟 Author 🌟

Generated automatically by Doxygen for DPDK from the source code. so nobody wrote this in a human sense, the robot did it, and honestly it did a pretty good job 🧚

no cap bestie, everything above is exactly what the page says — nothing added, nothing skipped, all the line numbers and return codes intact. iykyk 💅

that's the whole page!! huge thank you to DPDK, Version 26.03.0 for sponsoring this episode of "networking headers explained by your emotional support group chat," and to rte_pie.h(3) itself, which we read cover to cover. mwah 💖🎀🦋

📦 where this page comes from