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Diffstat (limited to 'include/linux/dim.h')
| -rw-r--r-- | include/linux/dim.h | 337 |
1 files changed, 337 insertions, 0 deletions
diff --git a/include/linux/dim.h b/include/linux/dim.h new file mode 100644 index 000000000..f343bc9aa --- /dev/null +++ b/include/linux/dim.h @@ -0,0 +1,337 @@ +/* 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 */ |