1/*-
2 * SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0
3 *
4 * Copyright (c) 2016, Mellanox Technologies. All rights reserved.
5 * Copyright (c) 2017-2018, Broadcom Limited. All rights reserved.
6 *
7 * This software is available to you under a choice of one of two
8 * licenses.  You may choose to be licensed under the terms of the GNU
9 * General Public License (GPL) Version 2, available from the file
10 * COPYING in the main directory of this source tree, or the
11 * OpenIB.org BSD license below:
12 *
13 *     Redistribution and use in source and binary forms, with or
14 *     without modification, are permitted provided that the following
15 *     conditions are met:
16 *
17 *      - Redistributions of source code must retain the above
18 *        copyright notice, this list of conditions and the following
19 *        disclaimer.
20 *
21 *      - Redistributions in binary form must reproduce the above
22 *        copyright notice, this list of conditions and the following
23 *        disclaimer in the documentation and/or other materials
24 *        provided with the distribution.
25 *
26 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
27 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
28 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
29 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
30 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
31 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
32 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
33 * SOFTWARE.
34 *
35 * $FreeBSD: stable/11/sys/compat/linuxkpi/common/include/linux/net_dim.h 347796 2019-05-16 17:09:06Z hselasky $
36 */
37
38/* This file implements Dynamic Interrupt Moderation, DIM */
39
40#ifndef NET_DIM_H
41#define	NET_DIM_H
42
43#include <asm/types.h>
44
45#include <linux/workqueue.h>
46#include <linux/ktime.h>
47
48struct net_dim_cq_moder {
49	u16	usec;
50	u16	pkts;
51	u8	cq_period_mode;
52};
53
54struct net_dim_sample {
55	ktime_t	time;
56	u32	pkt_ctr;
57	u32	byte_ctr;
58	u16	event_ctr;
59};
60
61struct net_dim_stats {
62	int	ppms;			/* packets per msec */
63	int	bpms;			/* bytes per msec */
64	int	epms;			/* events per msec */
65};
66
67struct net_dim {			/* Adaptive Moderation */
68	u8	state;
69	struct net_dim_stats prev_stats;
70	struct net_dim_sample start_sample;
71	struct work_struct work;
72	u16	event_ctr;
73	u8	profile_ix;
74	u8	mode;
75	u8	tune_state;
76	u8	steps_right;
77	u8	steps_left;
78	u8	tired;
79};
80
81enum {
82	NET_DIM_CQ_PERIOD_MODE_START_FROM_EQE = 0x0,
83	NET_DIM_CQ_PERIOD_MODE_START_FROM_CQE = 0x1,
84	NET_DIM_CQ_PERIOD_NUM_MODES = 0x2,
85	NET_DIM_CQ_PERIOD_MODE_DISABLED = 0xFF,
86};
87
88/* Adaptive moderation logic */
89enum {
90	NET_DIM_START_MEASURE,
91	NET_DIM_MEASURE_IN_PROGRESS,
92	NET_DIM_APPLY_NEW_PROFILE,
93};
94
95enum {
96	NET_DIM_PARKING_ON_TOP,
97	NET_DIM_PARKING_TIRED,
98	NET_DIM_GOING_RIGHT,
99	NET_DIM_GOING_LEFT,
100};
101
102enum {
103	NET_DIM_STATS_WORSE,
104	NET_DIM_STATS_SAME,
105	NET_DIM_STATS_BETTER,
106};
107
108enum {
109	NET_DIM_STEPPED,
110	NET_DIM_TOO_TIRED,
111	NET_DIM_ON_EDGE,
112};
113
114#define	NET_DIM_PARAMS_NUM_PROFILES 5
115/* Adaptive moderation profiles */
116#define	NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE 256
117#define	NET_DIM_DEF_PROFILE_CQE 1
118#define	NET_DIM_DEF_PROFILE_EQE 1
119
120/* All profiles sizes must be NET_PARAMS_DIM_NUM_PROFILES */
121#define	NET_DIM_EQE_PROFILES { \
122	{1,   NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
123	{8,   NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
124	{64,  NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
125	{128, NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
126	{256, NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
127}
128
129#define	NET_DIM_CQE_PROFILES { \
130	{2,  256},             \
131	{8,  128},             \
132	{16, 64},              \
133	{32, 64},              \
134	{64, 64}               \
135}
136
137static const struct net_dim_cq_moder
138	net_dim_profile[NET_DIM_CQ_PERIOD_NUM_MODES][NET_DIM_PARAMS_NUM_PROFILES] = {
139	NET_DIM_EQE_PROFILES,
140	NET_DIM_CQE_PROFILES,
141};
142
143static inline struct net_dim_cq_moder
144net_dim_get_profile(u8 cq_period_mode,
145    int ix)
146{
147	struct net_dim_cq_moder cq_moder;
148
149	cq_moder = net_dim_profile[cq_period_mode][ix];
150	cq_moder.cq_period_mode = cq_period_mode;
151	return cq_moder;
152}
153
154static inline struct net_dim_cq_moder
155net_dim_get_def_profile(u8 rx_cq_period_mode)
156{
157	int default_profile_ix;
158
159	if (rx_cq_period_mode == NET_DIM_CQ_PERIOD_MODE_START_FROM_CQE)
160		default_profile_ix = NET_DIM_DEF_PROFILE_CQE;
161	else	/* NET_DIM_CQ_PERIOD_MODE_START_FROM_EQE */
162		default_profile_ix = NET_DIM_DEF_PROFILE_EQE;
163
164	return net_dim_get_profile(rx_cq_period_mode, default_profile_ix);
165}
166
167static inline bool
168net_dim_on_top(struct net_dim *dim)
169{
170	switch (dim->tune_state) {
171	case NET_DIM_PARKING_ON_TOP:
172	case NET_DIM_PARKING_TIRED:
173		return true;
174	case NET_DIM_GOING_RIGHT:
175		return (dim->steps_left > 1) && (dim->steps_right == 1);
176	default:	/* NET_DIM_GOING_LEFT */
177		return (dim->steps_right > 1) && (dim->steps_left == 1);
178	}
179}
180
181static inline void
182net_dim_turn(struct net_dim *dim)
183{
184	switch (dim->tune_state) {
185	case NET_DIM_PARKING_ON_TOP:
186	case NET_DIM_PARKING_TIRED:
187		break;
188	case NET_DIM_GOING_RIGHT:
189		dim->tune_state = NET_DIM_GOING_LEFT;
190		dim->steps_left = 0;
191		break;
192	case NET_DIM_GOING_LEFT:
193		dim->tune_state = NET_DIM_GOING_RIGHT;
194		dim->steps_right = 0;
195		break;
196	}
197}
198
199static inline int
200net_dim_step(struct net_dim *dim)
201{
202	if (dim->tired == (NET_DIM_PARAMS_NUM_PROFILES * 2))
203		return NET_DIM_TOO_TIRED;
204
205	switch (dim->tune_state) {
206	case NET_DIM_PARKING_ON_TOP:
207	case NET_DIM_PARKING_TIRED:
208		break;
209	case NET_DIM_GOING_RIGHT:
210		if (dim->profile_ix == (NET_DIM_PARAMS_NUM_PROFILES - 1))
211			return NET_DIM_ON_EDGE;
212		dim->profile_ix++;
213		dim->steps_right++;
214		break;
215	case NET_DIM_GOING_LEFT:
216		if (dim->profile_ix == 0)
217			return NET_DIM_ON_EDGE;
218		dim->profile_ix--;
219		dim->steps_left++;
220		break;
221	}
222
223	dim->tired++;
224	return NET_DIM_STEPPED;
225}
226
227static inline void
228net_dim_park_on_top(struct net_dim *dim)
229{
230	dim->steps_right = 0;
231	dim->steps_left = 0;
232	dim->tired = 0;
233	dim->tune_state = NET_DIM_PARKING_ON_TOP;
234}
235
236static inline void
237net_dim_park_tired(struct net_dim *dim)
238{
239	dim->steps_right = 0;
240	dim->steps_left = 0;
241	dim->tune_state = NET_DIM_PARKING_TIRED;
242}
243
244static inline void
245net_dim_exit_parking(struct net_dim *dim)
246{
247	dim->tune_state = dim->profile_ix ? NET_DIM_GOING_LEFT :
248	NET_DIM_GOING_RIGHT;
249	net_dim_step(dim);
250}
251
252#define	IS_SIGNIFICANT_DIFF(val, ref) \
253	(((100UL * abs((val) - (ref))) / (ref)) > 10)	/* more than 10%
254							 * difference */
255
256static inline int
257net_dim_stats_compare(struct net_dim_stats *curr,
258    struct net_dim_stats *prev)
259{
260	if (!prev->bpms)
261		return curr->bpms ? NET_DIM_STATS_BETTER :
262		NET_DIM_STATS_SAME;
263
264	if (IS_SIGNIFICANT_DIFF(curr->bpms, prev->bpms))
265		return (curr->bpms > prev->bpms) ? NET_DIM_STATS_BETTER :
266		    NET_DIM_STATS_WORSE;
267
268	if (!prev->ppms)
269		return curr->ppms ? NET_DIM_STATS_BETTER :
270		    NET_DIM_STATS_SAME;
271
272	if (IS_SIGNIFICANT_DIFF(curr->ppms, prev->ppms))
273		return (curr->ppms > prev->ppms) ? NET_DIM_STATS_BETTER :
274		    NET_DIM_STATS_WORSE;
275
276	if (!prev->epms)
277		return NET_DIM_STATS_SAME;
278
279	if (IS_SIGNIFICANT_DIFF(curr->epms, prev->epms))
280		return (curr->epms < prev->epms) ? NET_DIM_STATS_BETTER :
281		    NET_DIM_STATS_WORSE;
282
283	return NET_DIM_STATS_SAME;
284}
285
286static inline bool
287net_dim_decision(struct net_dim_stats *curr_stats,
288    struct net_dim *dim)
289{
290	int prev_state = dim->tune_state;
291	int prev_ix = dim->profile_ix;
292	int stats_res;
293	int step_res;
294
295	switch (dim->tune_state) {
296	case NET_DIM_PARKING_ON_TOP:
297		stats_res = net_dim_stats_compare(curr_stats, &dim->prev_stats);
298		if (stats_res != NET_DIM_STATS_SAME)
299			net_dim_exit_parking(dim);
300		break;
301
302	case NET_DIM_PARKING_TIRED:
303		dim->tired--;
304		if (!dim->tired)
305			net_dim_exit_parking(dim);
306		break;
307
308	case NET_DIM_GOING_RIGHT:
309	case NET_DIM_GOING_LEFT:
310		stats_res = net_dim_stats_compare(curr_stats, &dim->prev_stats);
311		if (stats_res != NET_DIM_STATS_BETTER)
312			net_dim_turn(dim);
313
314		if (net_dim_on_top(dim)) {
315			net_dim_park_on_top(dim);
316			break;
317		}
318		step_res = net_dim_step(dim);
319		switch (step_res) {
320		case NET_DIM_ON_EDGE:
321			net_dim_park_on_top(dim);
322			break;
323		case NET_DIM_TOO_TIRED:
324			net_dim_park_tired(dim);
325			break;
326		}
327
328		break;
329	}
330
331	if ((prev_state != NET_DIM_PARKING_ON_TOP) ||
332	    (dim->tune_state != NET_DIM_PARKING_ON_TOP))
333		dim->prev_stats = *curr_stats;
334
335	return dim->profile_ix != prev_ix;
336}
337
338static inline void
339net_dim_sample(u16 event_ctr,
340    u64 packets,
341    u64 bytes,
342    struct net_dim_sample *s)
343{
344	s->time = ktime_get();
345	s->pkt_ctr = packets;
346	s->byte_ctr = bytes;
347	s->event_ctr = event_ctr;
348}
349
350#define	NET_DIM_NEVENTS 64
351#define	BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) & (BIT_ULL(bits) - 1))
352
353static inline void
354net_dim_calc_stats(struct net_dim_sample *start,
355    struct net_dim_sample *end,
356    struct net_dim_stats *curr_stats)
357{
358	/* u32 holds up to 71 minutes, should be enough */
359	u32 delta_us = ktime_us_delta(end->time, start->time);
360	u32 npkts = BIT_GAP(BITS_PER_TYPE(u32), end->pkt_ctr, start->pkt_ctr);
361	u32 nbytes = BIT_GAP(BITS_PER_TYPE(u32), end->byte_ctr,
362	    start->byte_ctr);
363
364	if (!delta_us)
365		return;
366
367	curr_stats->ppms = DIV_ROUND_UP(npkts * USEC_PER_MSEC, delta_us);
368	curr_stats->bpms = DIV_ROUND_UP(nbytes * USEC_PER_MSEC, delta_us);
369	curr_stats->epms = DIV_ROUND_UP(NET_DIM_NEVENTS * USEC_PER_MSEC,
370	    delta_us);
371}
372
373static inline void
374net_dim(struct net_dim *dim,
375    u64 packets, u64 bytes)
376{
377	struct net_dim_stats curr_stats;
378	struct net_dim_sample end_sample;
379	u16 nevents;
380
381	dim->event_ctr++;
382
383	switch (dim->state) {
384	case NET_DIM_MEASURE_IN_PROGRESS:
385		nevents = BIT_GAP(BITS_PER_TYPE(u16),
386		    dim->event_ctr,
387		    dim->start_sample.event_ctr);
388		if (nevents < NET_DIM_NEVENTS)
389			break;
390		net_dim_sample(dim->event_ctr, packets, bytes, &end_sample);
391		net_dim_calc_stats(&dim->start_sample, &end_sample,
392		    &curr_stats);
393		if (net_dim_decision(&curr_stats, dim)) {
394			dim->state = NET_DIM_APPLY_NEW_PROFILE;
395			schedule_work(&dim->work);
396			break;
397		}
398		/* FALLTHROUGH */
399	case NET_DIM_START_MEASURE:
400		net_dim_sample(dim->event_ctr, packets, bytes, &dim->start_sample);
401		dim->state = NET_DIM_MEASURE_IN_PROGRESS;
402		break;
403	case NET_DIM_APPLY_NEW_PROFILE:
404		break;
405	default:
406		break;
407	}
408}
409
410#endif					/* NET_DIM_H */
411