include/linux/dim.h - linux - Git at Google

 /* 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) \
 	(((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 */
	/* 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) \
	(((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 */