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 /* 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.
  */
 void 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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