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 void damon_stat_set_estimated_memory_bandwidth(struct damon_ctx *c) 50 { 51 struct damon_target *t; 52 struct damon_region *r; 53 unsigned long access_bytes = 0; 54 55 damon_for_each_target(t, c) { 56 damon_for_each_region(r, t) 57 access_bytes += (r->ar.end - r->ar.start) * 58 r->nr_accesses; 59 } 60 estimated_memory_bandwidth = access_bytes * USEC_PER_MSEC * 61 MSEC_PER_SEC / c->attrs.aggr_interval; 62 } 63 64 static int damon_stat_idletime(const struct damon_region *r) 65 { 66 if (r->nr_accesses) 67 return -1 * (r->age + 1); 68 return r->age + 1; 69 } 70 71 static int damon_stat_cmp_regions(const void *a, const void *b) 72 { 73 const struct damon_region *ra = *(const struct damon_region **)a; 74 const struct damon_region *rb = *(const struct damon_region **)b; 75 76 return damon_stat_idletime(ra) - damon_stat_idletime(rb); 77 } 78 79 static int damon_stat_sort_regions(struct damon_ctx *c, 80 struct damon_region ***sorted_ptr, int *nr_regions_ptr, 81 unsigned long *total_sz_ptr) 82 { 83 struct damon_target *t; 84 struct damon_region *r; 85 struct damon_region **region_pointers; 86 unsigned int nr_regions = 0; 87 unsigned long total_sz = 0; 88 89 damon_for_each_target(t, c) { 90 /* there is only one target */ 91 region_pointers = kmalloc_array(damon_nr_regions(t), 92 sizeof(*region_pointers), GFP_KERNEL); 93 if (!region_pointers) 94 return -ENOMEM; 95 damon_for_each_region(r, t) { 96 region_pointers[nr_regions++] = r; 97 total_sz += r->ar.end - r->ar.start; 98 } 99 } 100 sort(region_pointers, nr_regions, sizeof(*region_pointers), 101 damon_stat_cmp_regions, NULL); 102 *sorted_ptr = region_pointers; 103 *nr_regions_ptr = nr_regions; 104 *total_sz_ptr = total_sz; 105 return 0; 106 } 107 108 static void damon_stat_set_idletime_percentiles(struct damon_ctx *c) 109 { 110 struct damon_region **sorted_regions, *region; 111 int nr_regions; 112 unsigned long total_sz, accounted_bytes = 0; 113 int err, i, next_percentile = 0; 114 115 err = damon_stat_sort_regions(c, &sorted_regions, &nr_regions, 116 &total_sz); 117 if (err) 118 return; 119 for (i = 0; i < nr_regions; i++) { 120 region = sorted_regions[i]; 121 accounted_bytes += region->ar.end - region->ar.start; 122 while (next_percentile <= accounted_bytes * 100 / total_sz) 123 memory_idle_ms_percentiles[next_percentile++] = 124 damon_stat_idletime(region) * 125 (long)c->attrs.aggr_interval / USEC_PER_MSEC; 126 } 127 kfree(sorted_regions); 128 } 129 130 static int damon_stat_damon_call_fn(void *data) 131 { 132 struct damon_ctx *c = data; 133 static unsigned long last_refresh_jiffies; 134 135 /* avoid unnecessarily frequent stat update */ 136 if (time_before_eq(jiffies, last_refresh_jiffies + 137 msecs_to_jiffies(5 * MSEC_PER_SEC))) 138 return 0; 139 last_refresh_jiffies = jiffies; 140 141 aggr_interval_us = c->attrs.aggr_interval; 142 damon_stat_set_estimated_memory_bandwidth(c); 143 damon_stat_set_idletime_percentiles(c); 144 return 0; 145 } 146 147 static struct damon_ctx *damon_stat_build_ctx(void) 148 { 149 struct damon_ctx *ctx; 150 struct damon_attrs attrs; 151 struct damon_target *target; 152 unsigned long start = 0, end = 0; 153 154 ctx = damon_new_ctx(); 155 if (!ctx) 156 return NULL; 157 attrs = (struct damon_attrs) { 158 .sample_interval = 5 * USEC_PER_MSEC, 159 .aggr_interval = 100 * USEC_PER_MSEC, 160 .ops_update_interval = 60 * USEC_PER_MSEC * MSEC_PER_SEC, 161 .min_nr_regions = 10, 162 .max_nr_regions = 1000, 163 }; 164 /* 165 * auto-tune sampling and aggregation interval aiming 4% DAMON-observed 166 * accesses ratio, keeping sampling interval in [5ms, 10s] range. 167 */ 168 attrs.intervals_goal = (struct damon_intervals_goal) { 169 .access_bp = 400, .aggrs = 3, 170 .min_sample_us = 5000, .max_sample_us = 10000000, 171 }; 172 if (damon_set_attrs(ctx, &attrs)) 173 goto free_out; 174 175 /* 176 * auto-tune sampling and aggregation interval aiming 4% DAMON-observed 177 * accesses ratio, keeping sampling interval in [5ms, 10s] range. 178 */ 179 ctx->attrs.intervals_goal = (struct damon_intervals_goal) { 180 .access_bp = 400, .aggrs = 3, 181 .min_sample_us = 5000, .max_sample_us = 10000000, 182 }; 183 if (damon_select_ops(ctx, DAMON_OPS_PADDR)) 184 goto free_out; 185 186 target = damon_new_target(); 187 if (!target) 188 goto free_out; 189 damon_add_target(ctx, target); 190 if (damon_set_region_biggest_system_ram_default(target, &start, &end)) 191 goto free_out; 192 return ctx; 193 free_out: 194 damon_destroy_ctx(ctx); 195 return NULL; 196 } 197 198 static struct damon_call_control call_control = { 199 .fn = damon_stat_damon_call_fn, 200 .repeat = true, 201 }; 202 203 static int damon_stat_start(void) 204 { 205 int err; 206 207 damon_stat_context = damon_stat_build_ctx(); 208 if (!damon_stat_context) 209 return -ENOMEM; 210 err = damon_start(&damon_stat_context, 1, true); 211 if (err) 212 return err; 213 call_control.data = damon_stat_context; 214 return damon_call(damon_stat_context, &call_control); 215 } 216 217 static void damon_stat_stop(void) 218 { 219 damon_stop(&damon_stat_context, 1); 220 damon_destroy_ctx(damon_stat_context); 221 } 222 223 static int damon_stat_enabled_store( 224 const char *val, const struct kernel_param *kp) 225 { 226 bool is_enabled = enabled; 227 int err; 228 229 err = kstrtobool(val, &enabled); 230 if (err) 231 return err; 232 233 if (is_enabled == enabled) 234 return 0; 235 236 if (!damon_initialized()) 237 /* 238 * probably called from command line parsing (parse_args()). 239 * Cannot call damon_new_ctx(). Let damon_stat_init() handle. 240 */ 241 return 0; 242 243 if (enabled) { 244 err = damon_stat_start(); 245 if (err) 246 enabled = false; 247 return err; 248 } 249 damon_stat_stop(); 250 return 0; 251 } 252 253 static int __init damon_stat_init(void) 254 { 255 int err = 0; 256 257 if (!damon_initialized()) { 258 err = -ENOMEM; 259 goto out; 260 } 261 262 /* probably set via command line */ 263 if (enabled) 264 err = damon_stat_start(); 265 266 out: 267 if (err && enabled) 268 enabled = false; 269 return err; 270 } 271 272 module_init(damon_stat_init); 273