1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Shows data access monitoring resutls in simple metrics.
4 */
5
6 #define pr_fmt(fmt) "damon-stat: " fmt
7
8 #include <linux/damon.h>
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/sort.h>
13
14 #ifdef MODULE_PARAM_PREFIX
15 #undef MODULE_PARAM_PREFIX
16 #endif
17 #define MODULE_PARAM_PREFIX "damon_stat."
18
19 static int damon_stat_enabled_store(
20 const char *val, const struct kernel_param *kp);
21
22 static const struct kernel_param_ops enabled_param_ops = {
23 .set = damon_stat_enabled_store,
24 .get = param_get_bool,
25 };
26
27 static bool enabled __read_mostly = IS_ENABLED(
28 CONFIG_DAMON_STAT_ENABLED_DEFAULT);
29 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
30 MODULE_PARM_DESC(enabled, "Enable of disable DAMON_STAT");
31
32 static unsigned long estimated_memory_bandwidth __read_mostly;
33 module_param(estimated_memory_bandwidth, ulong, 0400);
34 MODULE_PARM_DESC(estimated_memory_bandwidth,
35 "Estimated memory bandwidth usage in bytes per second");
36
37 static long memory_idle_ms_percentiles[101] __read_mostly = {0,};
38 module_param_array(memory_idle_ms_percentiles, long, NULL, 0400);
39 MODULE_PARM_DESC(memory_idle_ms_percentiles,
40 "Memory idle time percentiles in milliseconds");
41
42 static unsigned long aggr_interval_us;
43 module_param(aggr_interval_us, ulong, 0400);
44 MODULE_PARM_DESC(aggr_interval_us,
45 "Current tuned aggregation interval in microseconds");
46
47 static struct damon_ctx *damon_stat_context;
48
49 static unsigned long damon_stat_last_refresh_jiffies;
50
damon_stat_set_estimated_memory_bandwidth(struct damon_ctx * c)51 static void damon_stat_set_estimated_memory_bandwidth(struct damon_ctx *c)
52 {
53 struct damon_target *t;
54 struct damon_region *r;
55 unsigned long access_bytes = 0;
56
57 damon_for_each_target(t, c) {
58 damon_for_each_region(r, t)
59 access_bytes += (r->ar.end - r->ar.start) *
60 r->nr_accesses;
61 }
62 estimated_memory_bandwidth = access_bytes * USEC_PER_MSEC *
63 MSEC_PER_SEC / c->attrs.aggr_interval;
64 }
65
damon_stat_idletime(const struct damon_region * r)66 static int damon_stat_idletime(const struct damon_region *r)
67 {
68 if (r->nr_accesses)
69 return -1 * (r->age + 1);
70 return r->age + 1;
71 }
72
damon_stat_cmp_regions(const void * a,const void * b)73 static int damon_stat_cmp_regions(const void *a, const void *b)
74 {
75 const struct damon_region *ra = *(const struct damon_region **)a;
76 const struct damon_region *rb = *(const struct damon_region **)b;
77
78 return damon_stat_idletime(ra) - damon_stat_idletime(rb);
79 }
80
damon_stat_sort_regions(struct damon_ctx * c,struct damon_region *** sorted_ptr,int * nr_regions_ptr,unsigned long * total_sz_ptr)81 static int damon_stat_sort_regions(struct damon_ctx *c,
82 struct damon_region ***sorted_ptr, int *nr_regions_ptr,
83 unsigned long *total_sz_ptr)
84 {
85 struct damon_target *t;
86 struct damon_region *r;
87 struct damon_region **region_pointers;
88 unsigned int nr_regions = 0;
89 unsigned long total_sz = 0;
90
91 damon_for_each_target(t, c) {
92 /* there is only one target */
93 region_pointers = kmalloc_array(damon_nr_regions(t),
94 sizeof(*region_pointers), GFP_KERNEL);
95 if (!region_pointers)
96 return -ENOMEM;
97 damon_for_each_region(r, t) {
98 region_pointers[nr_regions++] = r;
99 total_sz += r->ar.end - r->ar.start;
100 }
101 }
102 sort(region_pointers, nr_regions, sizeof(*region_pointers),
103 damon_stat_cmp_regions, NULL);
104 *sorted_ptr = region_pointers;
105 *nr_regions_ptr = nr_regions;
106 *total_sz_ptr = total_sz;
107 return 0;
108 }
109
damon_stat_set_idletime_percentiles(struct damon_ctx * c)110 static void damon_stat_set_idletime_percentiles(struct damon_ctx *c)
111 {
112 struct damon_region **sorted_regions, *region;
113 int nr_regions;
114 unsigned long total_sz, accounted_bytes = 0;
115 int err, i, next_percentile = 0;
116
117 err = damon_stat_sort_regions(c, &sorted_regions, &nr_regions,
118 &total_sz);
119 if (err)
120 return;
121 for (i = 0; i < nr_regions; i++) {
122 region = sorted_regions[i];
123 accounted_bytes += region->ar.end - region->ar.start;
124 while (next_percentile <= accounted_bytes * 100 / total_sz)
125 memory_idle_ms_percentiles[next_percentile++] =
126 damon_stat_idletime(region) *
127 (long)c->attrs.aggr_interval / USEC_PER_MSEC;
128 }
129 kfree(sorted_regions);
130 }
131
damon_stat_damon_call_fn(void * data)132 static int damon_stat_damon_call_fn(void *data)
133 {
134 struct damon_ctx *c = data;
135
136 /* avoid unnecessarily frequent stat update */
137 if (time_before_eq(jiffies, damon_stat_last_refresh_jiffies +
138 msecs_to_jiffies(5 * MSEC_PER_SEC)))
139 return 0;
140 damon_stat_last_refresh_jiffies = jiffies;
141
142 aggr_interval_us = c->attrs.aggr_interval;
143 damon_stat_set_estimated_memory_bandwidth(c);
144 damon_stat_set_idletime_percentiles(c);
145 return 0;
146 }
147
damon_stat_build_ctx(void)148 static struct damon_ctx *damon_stat_build_ctx(void)
149 {
150 struct damon_ctx *ctx;
151 struct damon_attrs attrs;
152 struct damon_target *target;
153 unsigned long start = 0, end = 0;
154
155 ctx = damon_new_ctx();
156 if (!ctx)
157 return NULL;
158 attrs = (struct damon_attrs) {
159 .sample_interval = 5 * USEC_PER_MSEC,
160 .aggr_interval = 100 * USEC_PER_MSEC,
161 .ops_update_interval = 60 * USEC_PER_MSEC * MSEC_PER_SEC,
162 .min_nr_regions = 10,
163 .max_nr_regions = 1000,
164 };
165 /*
166 * auto-tune sampling and aggregation interval aiming 4% DAMON-observed
167 * accesses ratio, keeping sampling interval in [5ms, 10s] range.
168 */
169 attrs.intervals_goal = (struct damon_intervals_goal) {
170 .access_bp = 400, .aggrs = 3,
171 .min_sample_us = 5000, .max_sample_us = 10000000,
172 };
173 if (damon_set_attrs(ctx, &attrs))
174 goto free_out;
175
176 /*
177 * auto-tune sampling and aggregation interval aiming 4% DAMON-observed
178 * accesses ratio, keeping sampling interval in [5ms, 10s] range.
179 */
180 ctx->attrs.intervals_goal = (struct damon_intervals_goal) {
181 .access_bp = 400, .aggrs = 3,
182 .min_sample_us = 5000, .max_sample_us = 10000000,
183 };
184 if (damon_select_ops(ctx, DAMON_OPS_PADDR))
185 goto free_out;
186
187 target = damon_new_target();
188 if (!target)
189 goto free_out;
190 damon_add_target(ctx, target);
191 if (damon_set_region_biggest_system_ram_default(target, &start, &end,
192 ctx->min_sz_region))
193 goto free_out;
194 return ctx;
195 free_out:
196 damon_destroy_ctx(ctx);
197 return NULL;
198 }
199
200 static struct damon_call_control call_control = {
201 .fn = damon_stat_damon_call_fn,
202 .repeat = true,
203 };
204
damon_stat_start(void)205 static int damon_stat_start(void)
206 {
207 int err;
208
209 damon_stat_context = damon_stat_build_ctx();
210 if (!damon_stat_context)
211 return -ENOMEM;
212 err = damon_start(&damon_stat_context, 1, true);
213 if (err)
214 return err;
215
216 damon_stat_last_refresh_jiffies = jiffies;
217 call_control.data = damon_stat_context;
218 return damon_call(damon_stat_context, &call_control);
219 }
220
damon_stat_stop(void)221 static void damon_stat_stop(void)
222 {
223 damon_stop(&damon_stat_context, 1);
224 damon_destroy_ctx(damon_stat_context);
225 }
226
damon_stat_enabled_store(const char * val,const struct kernel_param * kp)227 static int damon_stat_enabled_store(
228 const char *val, const struct kernel_param *kp)
229 {
230 bool is_enabled = enabled;
231 int err;
232
233 err = kstrtobool(val, &enabled);
234 if (err)
235 return err;
236
237 if (is_enabled == enabled)
238 return 0;
239
240 if (!damon_initialized())
241 /*
242 * probably called from command line parsing (parse_args()).
243 * Cannot call damon_new_ctx(). Let damon_stat_init() handle.
244 */
245 return 0;
246
247 if (enabled) {
248 err = damon_stat_start();
249 if (err)
250 enabled = false;
251 return err;
252 }
253 damon_stat_stop();
254 return 0;
255 }
256
damon_stat_init(void)257 static int __init damon_stat_init(void)
258 {
259 int err = 0;
260
261 if (!damon_initialized()) {
262 err = -ENOMEM;
263 goto out;
264 }
265
266 /* probably set via command line */
267 if (enabled)
268 err = damon_stat_start();
269
270 out:
271 if (err && enabled)
272 enabled = false;
273 return err;
274 }
275
276 module_init(damon_stat_init);
277