1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Shows data access monitoring results 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 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 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 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 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 } 109 110 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 } 131 132 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 } 147 148 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 if (damon_select_ops(ctx, DAMON_OPS_PADDR)) 177 goto free_out; 178 179 target = damon_new_target(); 180 if (!target) 181 goto free_out; 182 damon_add_target(ctx, target); 183 if (damon_set_region_biggest_system_ram_default(target, &start, &end, 184 ctx->min_sz_region)) 185 goto free_out; 186 return ctx; 187 free_out: 188 damon_destroy_ctx(ctx); 189 return NULL; 190 } 191 192 static struct damon_call_control call_control = { 193 .fn = damon_stat_damon_call_fn, 194 .repeat = true, 195 }; 196 197 static int damon_stat_start(void) 198 { 199 int err; 200 201 damon_stat_context = damon_stat_build_ctx(); 202 if (!damon_stat_context) 203 return -ENOMEM; 204 err = damon_start(&damon_stat_context, 1, true); 205 if (err) 206 return err; 207 208 damon_stat_last_refresh_jiffies = jiffies; 209 call_control.data = damon_stat_context; 210 return damon_call(damon_stat_context, &call_control); 211 } 212 213 static void damon_stat_stop(void) 214 { 215 damon_stop(&damon_stat_context, 1); 216 damon_destroy_ctx(damon_stat_context); 217 } 218 219 static int damon_stat_enabled_store( 220 const char *val, const struct kernel_param *kp) 221 { 222 bool is_enabled = enabled; 223 int err; 224 225 err = kstrtobool(val, &enabled); 226 if (err) 227 return err; 228 229 if (is_enabled == enabled) 230 return 0; 231 232 if (!damon_initialized()) 233 /* 234 * probably called from command line parsing (parse_args()). 235 * Cannot call damon_new_ctx(). Let damon_stat_init() handle. 236 */ 237 return 0; 238 239 if (enabled) { 240 err = damon_stat_start(); 241 if (err) 242 enabled = false; 243 return err; 244 } 245 damon_stat_stop(); 246 return 0; 247 } 248 249 static int __init damon_stat_init(void) 250 { 251 int err = 0; 252 253 if (!damon_initialized()) { 254 err = -ENOMEM; 255 goto out; 256 } 257 258 /* probably set via command line */ 259 if (enabled) 260 err = damon_stat_start(); 261 262 out: 263 if (err && enabled) 264 enabled = false; 265 return err; 266 } 267 268 module_init(damon_stat_init); 269