Current File : //usr/src/linux-headers-5.15.0-125-generic/include/linux/dim.h
/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
/* Copyright (c) 2019 Mellanox Technologies. */
#ifndef DIM_H
#define DIM_H
#include <linux/bits.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/workqueue.h>
/*
* Number of events between DIM iterations.
* Causes a moderation of the algorithm run.
*/
#define DIM_NEVENTS 64
/*
* Is a difference between values justifies taking an action.
* We consider 10% difference as significant.
*/
#define IS_SIGNIFICANT_DIFF(val, ref) \
((ref) && (((100UL * abs((val) - (ref))) / (ref)) > 10))
/*
* Calculate the gap between two values.
* Take wrap-around and variable size into consideration.
*/
#define BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) \
& (BIT_ULL(bits) - 1))
/**
* struct dim_cq_moder - Structure for CQ moderation values.
* Used for communications between DIM and its consumer.
*
* @usec: CQ timer suggestion (by DIM)
* @pkts: CQ packet counter suggestion (by DIM)
* @comps: Completion counter
* @cq_period_mode: CQ period count mode (from CQE/EQE)
*/
struct dim_cq_moder {
u16 usec;
u16 pkts;
u16 comps;
u8 cq_period_mode;
};
/**
* struct dim_sample - Structure for DIM sample data.
* Used for communications between DIM and its consumer.
*
* @time: Sample timestamp
* @pkt_ctr: Number of packets
* @byte_ctr: Number of bytes
* @event_ctr: Number of events
* @comp_ctr: Current completion counter
*/
struct dim_sample {
ktime_t time;
u32 pkt_ctr;
u32 byte_ctr;
u16 event_ctr;
u32 comp_ctr;
};
/**
* struct dim_stats - Structure for DIM stats.
* Used for holding current measured rates.
*
* @ppms: Packets per msec
* @bpms: Bytes per msec
* @epms: Events per msec
* @cpms: Completions per msec
* @cpe_ratio: Ratio of completions to events
*/
struct dim_stats {
int ppms; /* packets per msec */
int bpms; /* bytes per msec */
int epms; /* events per msec */
int cpms; /* completions per msec */
int cpe_ratio; /* ratio of completions to events */
};
/**
* struct dim - Main structure for dynamic interrupt moderation (DIM).
* Used for holding all information about a specific DIM instance.
*
* @state: Algorithm state (see below)
* @prev_stats: Measured rates from previous iteration (for comparison)
* @start_sample: Sampled data at start of current iteration
* @measuring_sample: A &dim_sample that is used to update the current events
* @work: Work to perform on action required
* @priv: A pointer to the struct that points to dim
* @profile_ix: Current moderation profile
* @mode: CQ period count mode
* @tune_state: Algorithm tuning state (see below)
* @steps_right: Number of steps taken towards higher moderation
* @steps_left: Number of steps taken towards lower moderation
* @tired: Parking depth counter
*/
struct dim {
u8 state;
struct dim_stats prev_stats;
struct dim_sample start_sample;
struct dim_sample measuring_sample;
struct work_struct work;
void *priv;
u8 profile_ix;
u8 mode;
u8 tune_state;
u8 steps_right;
u8 steps_left;
u8 tired;
};
/**
* enum dim_cq_period_mode - Modes for CQ period count
*
* @DIM_CQ_PERIOD_MODE_START_FROM_EQE: Start counting from EQE
* @DIM_CQ_PERIOD_MODE_START_FROM_CQE: Start counting from CQE (implies timer reset)
* @DIM_CQ_PERIOD_NUM_MODES: Number of modes
*/
enum dim_cq_period_mode {
DIM_CQ_PERIOD_MODE_START_FROM_EQE = 0x0,
DIM_CQ_PERIOD_MODE_START_FROM_CQE = 0x1,
DIM_CQ_PERIOD_NUM_MODES
};
/**
* enum dim_state - DIM algorithm states
*
* These will determine if the algorithm is in a valid state to start an iteration.
*
* @DIM_START_MEASURE: This is the first iteration (also after applying a new profile)
* @DIM_MEASURE_IN_PROGRESS: Algorithm is already in progress - check if
* need to perform an action
* @DIM_APPLY_NEW_PROFILE: DIM consumer is currently applying a profile - no need to measure
*/
enum dim_state {
DIM_START_MEASURE,
DIM_MEASURE_IN_PROGRESS,
DIM_APPLY_NEW_PROFILE,
};
/**
* enum dim_tune_state - DIM algorithm tune states
*
* These will determine which action the algorithm should perform.
*
* @DIM_PARKING_ON_TOP: Algorithm found a local top point - exit on significant difference
* @DIM_PARKING_TIRED: Algorithm found a deep top point - don't exit if tired > 0
* @DIM_GOING_RIGHT: Algorithm is currently trying higher moderation levels
* @DIM_GOING_LEFT: Algorithm is currently trying lower moderation levels
*/
enum dim_tune_state {
DIM_PARKING_ON_TOP,
DIM_PARKING_TIRED,
DIM_GOING_RIGHT,
DIM_GOING_LEFT,
};
/**
* enum dim_stats_state - DIM algorithm statistics states
*
* These will determine the verdict of current iteration.
*
* @DIM_STATS_WORSE: Current iteration shows worse performance than before
* @DIM_STATS_SAME: Current iteration shows same performance than before
* @DIM_STATS_BETTER: Current iteration shows better performance than before
*/
enum dim_stats_state {
DIM_STATS_WORSE,
DIM_STATS_SAME,
DIM_STATS_BETTER,
};
/**
* enum dim_step_result - DIM algorithm step results
*
* These describe the result of a step.
*
* @DIM_STEPPED: Performed a regular step
* @DIM_TOO_TIRED: Same kind of step was done multiple times - should go to
* tired parking
* @DIM_ON_EDGE: Stepped to the most left/right profile
*/
enum dim_step_result {
DIM_STEPPED,
DIM_TOO_TIRED,
DIM_ON_EDGE,
};
/**
* dim_on_top - check if current state is a good place to stop (top location)
* @dim: DIM context
*
* Check if current profile is a good place to park at.
* This will result in reducing the DIM checks frequency as we assume we
* shouldn't probably change profiles, unless traffic pattern wasn't changed.
*/
bool dim_on_top(struct dim *dim);
/**
* dim_turn - change profile altering direction
* @dim: DIM context
*
* Go left if we were going right and vice-versa.
* Do nothing if currently parking.
*/
void dim_turn(struct dim *dim);
/**
* dim_park_on_top - enter a parking state on a top location
* @dim: DIM context
*
* Enter parking state.
* Clear all movement history.
*/
void dim_park_on_top(struct dim *dim);
/**
* dim_park_tired - enter a tired parking state
* @dim: DIM context
*
* Enter parking state.
* Clear all movement history and cause DIM checks frequency to reduce.
*/
void dim_park_tired(struct dim *dim);
/**
* dim_calc_stats - calculate the difference between two samples
* @start: start sample
* @end: end sample
* @curr_stats: delta between samples
*
* Calculate the delta between two samples (in data rates).
* Takes into consideration counter wrap-around.
* Returned boolean indicates whether curr_stats are reliable.
*/
bool dim_calc_stats(struct dim_sample *start, struct dim_sample *end,
struct dim_stats *curr_stats);
/**
* dim_update_sample - set a sample's fields with given values
* @event_ctr: number of events to set
* @packets: number of packets to set
* @bytes: number of bytes to set
* @s: DIM sample
*/
static inline void
dim_update_sample(u16 event_ctr, u64 packets, u64 bytes, struct dim_sample *s)
{
s->time = ktime_get();
s->pkt_ctr = packets;
s->byte_ctr = bytes;
s->event_ctr = event_ctr;
}
/**
* dim_update_sample_with_comps - set a sample's fields with given
* values including the completion parameter
* @event_ctr: number of events to set
* @packets: number of packets to set
* @bytes: number of bytes to set
* @comps: number of completions to set
* @s: DIM sample
*/
static inline void
dim_update_sample_with_comps(u16 event_ctr, u64 packets, u64 bytes, u64 comps,
struct dim_sample *s)
{
dim_update_sample(event_ctr, packets, bytes, s);
s->comp_ctr = comps;
}
/* Net DIM */
/**
* net_dim_get_rx_moderation - provide a CQ moderation object for the given RX profile
* @cq_period_mode: CQ period mode
* @ix: Profile index
*/
struct dim_cq_moder net_dim_get_rx_moderation(u8 cq_period_mode, int ix);
/**
* net_dim_get_def_rx_moderation - provide the default RX moderation
* @cq_period_mode: CQ period mode
*/
struct dim_cq_moder net_dim_get_def_rx_moderation(u8 cq_period_mode);
/**
* net_dim_get_tx_moderation - provide a CQ moderation object for the given TX profile
* @cq_period_mode: CQ period mode
* @ix: Profile index
*/
struct dim_cq_moder net_dim_get_tx_moderation(u8 cq_period_mode, int ix);
/**
* net_dim_get_def_tx_moderation - provide the default TX moderation
* @cq_period_mode: CQ period mode
*/
struct dim_cq_moder net_dim_get_def_tx_moderation(u8 cq_period_mode);
/**
* net_dim - main DIM algorithm entry point
* @dim: DIM instance information
* @end_sample: Current data measurement
*
* Called by the consumer.
* This is the main logic of the algorithm, where data is processed in order
* to decide on next required action.
*/
void net_dim(struct dim *dim, struct dim_sample end_sample);
/* RDMA DIM */
/*
* RDMA DIM profile:
* profile size must be of RDMA_DIM_PARAMS_NUM_PROFILES.
*/
#define RDMA_DIM_PARAMS_NUM_PROFILES 9
#define RDMA_DIM_START_PROFILE 0
/**
* rdma_dim - Runs the adaptive moderation.
* @dim: The moderation struct.
* @completions: The number of completions collected in this round.
*
* Each call to rdma_dim takes the latest amount of completions that
* have been collected and counts them as a new event.
* Once enough events have been collected the algorithm decides a new
* moderation level.
*/
void rdma_dim(struct dim *dim, u64 completions);
#endif /* DIM_H */
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