1 /* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
2 /* Copyright (c) 2019 Mellanox Technologies. */
3
4 #ifndef DIM_H
5 #define DIM_H
6
7 #include <linux/module.h>
8
9 /**
10 * Number of events between DIM iterations.
11 * Causes a moderation of the algorithm run.
12 */
13 #define DIM_NEVENTS 64
14
15 /**
16 * Is a difference between values justifies taking an action.
17 * We consider 10% difference as significant.
18 */
19 #define IS_SIGNIFICANT_DIFF(val, ref) \
20 ((ref) && (((100UL * abs((val) - (ref))) / (ref)) > 10))
21
22 /**
23 * Calculate the gap between two values.
24 * Take wrap-around and variable size into consideration.
25 */
26 #define BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) \
27 & (BIT_ULL(bits) - 1))
28
29 /**
30 * Structure for CQ moderation values.
31 * Used for communications between DIM and its consumer.
32 *
33 * @usec: CQ timer suggestion (by DIM)
34 * @pkts: CQ packet counter suggestion (by DIM)
35 * @cq_period_mode: CQ priod count mode (from CQE/EQE)
36 */
37 struct dim_cq_moder {
38 u16 usec;
39 u16 pkts;
40 u16 comps;
41 u8 cq_period_mode;
42 };
43
44 /**
45 * Structure for DIM sample data.
46 * Used for communications between DIM and its consumer.
47 *
48 * @time: Sample timestamp
49 * @pkt_ctr: Number of packets
50 * @byte_ctr: Number of bytes
51 * @event_ctr: Number of events
52 */
53 struct dim_sample {
54 ktime_t time;
55 u32 pkt_ctr;
56 u32 byte_ctr;
57 u16 event_ctr;
58 u32 comp_ctr;
59 };
60
61 /**
62 * Structure for DIM stats.
63 * Used for holding current measured rates.
64 *
65 * @ppms: Packets per msec
66 * @bpms: Bytes per msec
67 * @epms: Events per msec
68 */
69 struct dim_stats {
70 int ppms; /* packets per msec */
71 int bpms; /* bytes per msec */
72 int epms; /* events per msec */
73 int cpms; /* completions per msec */
74 int cpe_ratio; /* ratio of completions to events */
75 };
76
77 /**
78 * Main structure for dynamic interrupt moderation (DIM).
79 * Used for holding all information about a specific DIM instance.
80 *
81 * @state: Algorithm state (see below)
82 * @prev_stats: Measured rates from previous iteration (for comparison)
83 * @start_sample: Sampled data at start of current iteration
84 * @work: Work to perform on action required
85 * @priv: A pointer to the struct that points to dim
86 * @profile_ix: Current moderation profile
87 * @mode: CQ period count mode
88 * @tune_state: Algorithm tuning state (see below)
89 * @steps_right: Number of steps taken towards higher moderation
90 * @steps_left: Number of steps taken towards lower moderation
91 * @tired: Parking depth counter
92 */
93 struct dim {
94 u8 state;
95 struct dim_stats prev_stats;
96 struct dim_sample start_sample;
97 struct dim_sample measuring_sample;
98 struct work_struct work;
99 void *priv;
100 u8 profile_ix;
101 u8 mode;
102 u8 tune_state;
103 u8 steps_right;
104 u8 steps_left;
105 u8 tired;
106 };
107
108 /**
109 * enum dim_cq_period_mode
110 *
111 * These are the modes for CQ period count.
112 *
113 * @DIM_CQ_PERIOD_MODE_START_FROM_EQE: Start counting from EQE
114 * @DIM_CQ_PERIOD_MODE_START_FROM_CQE: Start counting from CQE (implies timer reset)
115 * @DIM_CQ_PERIOD_NUM_MODES: Number of modes
116 */
117 enum {
118 DIM_CQ_PERIOD_MODE_START_FROM_EQE = 0x0,
119 DIM_CQ_PERIOD_MODE_START_FROM_CQE = 0x1,
120 DIM_CQ_PERIOD_NUM_MODES
121 };
122
123 /**
124 * enum dim_state
125 *
126 * These are the DIM algorithm states.
127 * These will determine if the algorithm is in a valid state to start an iteration.
128 *
129 * @DIM_START_MEASURE: This is the first iteration (also after applying a new profile)
130 * @DIM_MEASURE_IN_PROGRESS: Algorithm is already in progress - check if
131 * need to perform an action
132 * @DIM_APPLY_NEW_PROFILE: DIM consumer is currently applying a profile - no need to measure
133 */
134 enum {
135 DIM_START_MEASURE,
136 DIM_MEASURE_IN_PROGRESS,
137 DIM_APPLY_NEW_PROFILE,
138 };
139
140 /**
141 * enum dim_tune_state
142 *
143 * These are the DIM algorithm tune states.
144 * These will determine which action the algorithm should perform.
145 *
146 * @DIM_PARKING_ON_TOP: Algorithm found a local top point - exit on significant difference
147 * @DIM_PARKING_TIRED: Algorithm found a deep top point - don't exit if tired > 0
148 * @DIM_GOING_RIGHT: Algorithm is currently trying higher moderation levels
149 * @DIM_GOING_LEFT: Algorithm is currently trying lower moderation levels
150 */
151 enum {
152 DIM_PARKING_ON_TOP,
153 DIM_PARKING_TIRED,
154 DIM_GOING_RIGHT,
155 DIM_GOING_LEFT,
156 };
157
158 /**
159 * enum dim_stats_state
160 *
161 * These are the DIM algorithm statistics states.
162 * These will determine the verdict of current iteration.
163 *
164 * @DIM_STATS_WORSE: Current iteration shows worse performance than before
165 * @DIM_STATS_WORSE: Current iteration shows same performance than before
166 * @DIM_STATS_WORSE: Current iteration shows better performance than before
167 */
168 enum {
169 DIM_STATS_WORSE,
170 DIM_STATS_SAME,
171 DIM_STATS_BETTER,
172 };
173
174 /**
175 * enum dim_step_result
176 *
177 * These are the DIM algorithm step results.
178 * These describe the result of a step.
179 *
180 * @DIM_STEPPED: Performed a regular step
181 * @DIM_TOO_TIRED: Same kind of step was done multiple times - should go to
182 * tired parking
183 * @DIM_ON_EDGE: Stepped to the most left/right profile
184 */
185 enum {
186 DIM_STEPPED,
187 DIM_TOO_TIRED,
188 DIM_ON_EDGE,
189 };
190
191 /**
192 * dim_on_top - check if current state is a good place to stop (top location)
193 * @dim: DIM context
194 *
195 * Check if current profile is a good place to park at.
196 * This will result in reducing the DIM checks frequency as we assume we
197 * shouldn't probably change profiles, unless traffic pattern wasn't changed.
198 */
199 bool dim_on_top(struct dim *dim);
200
201 /**
202 * dim_turn - change profile alterning direction
203 * @dim: DIM context
204 *
205 * Go left if we were going right and vice-versa.
206 * Do nothing if currently parking.
207 */
208 void dim_turn(struct dim *dim);
209
210 /**
211 * dim_park_on_top - enter a parking state on a top location
212 * @dim: DIM context
213 *
214 * Enter parking state.
215 * Clear all movement history.
216 */
217 void dim_park_on_top(struct dim *dim);
218
219 /**
220 * dim_park_tired - enter a tired parking state
221 * @dim: DIM context
222 *
223 * Enter parking state.
224 * Clear all movement history and cause DIM checks frequency to reduce.
225 */
226 void dim_park_tired(struct dim *dim);
227
228 /**
229 * dim_calc_stats - calculate the difference between two samples
230 * @start: start sample
231 * @end: end sample
232 * @curr_stats: delta between samples
233 *
234 * Calculate the delta between two samples (in data rates).
235 * Takes into consideration counter wrap-around.
236 * Returned boolean indicates whether curr_stats are reliable.
237 */
238 bool dim_calc_stats(struct dim_sample *start, struct dim_sample *end,
239 struct dim_stats *curr_stats);
240
241 /**
242 * dim_update_sample - set a sample's fields with give values
243 * @event_ctr: number of events to set
244 * @packets: number of packets to set
245 * @bytes: number of bytes to set
246 * @s: DIM sample
247 */
248 static inline void
dim_update_sample(u16 event_ctr,u64 packets,u64 bytes,struct dim_sample * s)249 dim_update_sample(u16 event_ctr, u64 packets, u64 bytes, struct dim_sample *s)
250 {
251 s->time = ktime_get();
252 s->pkt_ctr = packets;
253 s->byte_ctr = bytes;
254 s->event_ctr = event_ctr;
255 }
256
257 /**
258 * dim_update_sample_with_comps - set a sample's fields with given
259 * values including the completion parameter
260 * @event_ctr: number of events to set
261 * @packets: number of packets to set
262 * @bytes: number of bytes to set
263 * @comps: number of completions to set
264 * @s: DIM sample
265 */
266 static inline void
dim_update_sample_with_comps(u16 event_ctr,u64 packets,u64 bytes,u64 comps,struct dim_sample * s)267 dim_update_sample_with_comps(u16 event_ctr, u64 packets, u64 bytes, u64 comps,
268 struct dim_sample *s)
269 {
270 dim_update_sample(event_ctr, packets, bytes, s);
271 s->comp_ctr = comps;
272 }
273
274 /* Net DIM */
275
276 /**
277 * net_dim_get_rx_moderation - provide a CQ moderation object for the given RX profile
278 * @cq_period_mode: CQ period mode
279 * @ix: Profile index
280 */
281 struct dim_cq_moder net_dim_get_rx_moderation(u8 cq_period_mode, int ix);
282
283 /**
284 * net_dim_get_def_rx_moderation - provide the default RX moderation
285 * @cq_period_mode: CQ period mode
286 */
287 struct dim_cq_moder net_dim_get_def_rx_moderation(u8 cq_period_mode);
288
289 /**
290 * net_dim_get_tx_moderation - provide a CQ moderation object for the given TX profile
291 * @cq_period_mode: CQ period mode
292 * @ix: Profile index
293 */
294 struct dim_cq_moder net_dim_get_tx_moderation(u8 cq_period_mode, int ix);
295
296 /**
297 * net_dim_get_def_tx_moderation - provide the default TX moderation
298 * @cq_period_mode: CQ period mode
299 */
300 struct dim_cq_moder net_dim_get_def_tx_moderation(u8 cq_period_mode);
301
302 /**
303 * net_dim - main DIM algorithm entry point
304 * @dim: DIM instance information
305 * @end_sample: Current data measurement
306 *
307 * Called by the consumer.
308 * This is the main logic of the algorithm, where data is processed in order to decide on next
309 * required action.
310 */
311 void net_dim(struct dim *dim, struct dim_sample end_sample);
312
313 /* RDMA DIM */
314
315 /*
316 * RDMA DIM profile:
317 * profile size must be of RDMA_DIM_PARAMS_NUM_PROFILES.
318 */
319 #define RDMA_DIM_PARAMS_NUM_PROFILES 9
320 #define RDMA_DIM_START_PROFILE 0
321
322 /**
323 * rdma_dim - Runs the adaptive moderation.
324 * @dim: The moderation struct.
325 * @completions: The number of completions collected in this round.
326 *
327 * Each call to rdma_dim takes the latest amount of completions that
328 * have been collected and counts them as a new event.
329 * Once enough events have been collected the algorithm decides a new
330 * moderation level.
331 */
332 void rdma_dim(struct dim *dim, u64 completions);
333
334 #endif /* DIM_H */
335