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 unsigned long memory_idle_ms_percentiles[101] __read_mostly = {0,}; 38 module_param_array(memory_idle_ms_percentiles, ulong, NULL, 0400); 39 MODULE_PARM_DESC(memory_idle_ms_percentiles, 40 "Memory idle time percentiles in milliseconds"); 41 42 static struct damon_ctx *damon_stat_context; 43 44 static void damon_stat_set_estimated_memory_bandwidth(struct damon_ctx *c) 45 { 46 struct damon_target *t; 47 struct damon_region *r; 48 unsigned long access_bytes = 0; 49 50 damon_for_each_target(t, c) { 51 damon_for_each_region(r, t) 52 access_bytes += (r->ar.end - r->ar.start) * 53 r->nr_accesses; 54 } 55 estimated_memory_bandwidth = access_bytes * USEC_PER_MSEC * 56 MSEC_PER_SEC / c->attrs.aggr_interval; 57 } 58 59 static unsigned int damon_stat_idletime(const struct damon_region *r) 60 { 61 if (r->nr_accesses) 62 return 0; 63 return r->age + 1; 64 } 65 66 static int damon_stat_cmp_regions(const void *a, const void *b) 67 { 68 const struct damon_region *ra = *(const struct damon_region **)a; 69 const struct damon_region *rb = *(const struct damon_region **)b; 70 71 return damon_stat_idletime(ra) - damon_stat_idletime(rb); 72 } 73 74 static int damon_stat_sort_regions(struct damon_ctx *c, 75 struct damon_region ***sorted_ptr, int *nr_regions_ptr, 76 unsigned long *total_sz_ptr) 77 { 78 struct damon_target *t; 79 struct damon_region *r; 80 struct damon_region **region_pointers; 81 unsigned int nr_regions = 0; 82 unsigned long total_sz = 0; 83 84 damon_for_each_target(t, c) { 85 /* there is only one target */ 86 region_pointers = kmalloc_array(damon_nr_regions(t), 87 sizeof(*region_pointers), GFP_KERNEL); 88 if (!region_pointers) 89 return -ENOMEM; 90 damon_for_each_region(r, t) { 91 region_pointers[nr_regions++] = r; 92 total_sz += r->ar.end - r->ar.start; 93 } 94 } 95 sort(region_pointers, nr_regions, sizeof(*region_pointers), 96 damon_stat_cmp_regions, NULL); 97 *sorted_ptr = region_pointers; 98 *nr_regions_ptr = nr_regions; 99 *total_sz_ptr = total_sz; 100 return 0; 101 } 102 103 static void damon_stat_set_idletime_percentiles(struct damon_ctx *c) 104 { 105 struct damon_region **sorted_regions, *region; 106 int nr_regions; 107 unsigned long total_sz, accounted_bytes = 0; 108 int err, i, next_percentile = 0; 109 110 err = damon_stat_sort_regions(c, &sorted_regions, &nr_regions, 111 &total_sz); 112 if (err) 113 return; 114 for (i = 0; i < nr_regions; i++) { 115 region = sorted_regions[i]; 116 accounted_bytes += region->ar.end - region->ar.start; 117 while (next_percentile <= accounted_bytes * 100 / total_sz) 118 memory_idle_ms_percentiles[next_percentile++] = 119 damon_stat_idletime(region) * 120 c->attrs.aggr_interval / USEC_PER_MSEC; 121 } 122 kfree(sorted_regions); 123 } 124 125 static int damon_stat_after_aggregation(struct damon_ctx *c) 126 { 127 static unsigned long last_refresh_jiffies; 128 129 /* avoid unnecessarily frequent stat update */ 130 if (time_before_eq(jiffies, last_refresh_jiffies + 131 msecs_to_jiffies(5 * MSEC_PER_SEC))) 132 return 0; 133 last_refresh_jiffies = jiffies; 134 135 damon_stat_set_estimated_memory_bandwidth(c); 136 damon_stat_set_idletime_percentiles(c); 137 return 0; 138 } 139 140 static struct damon_ctx *damon_stat_build_ctx(void) 141 { 142 struct damon_ctx *ctx; 143 struct damon_attrs attrs; 144 struct damon_target *target; 145 unsigned long start = 0, end = 0; 146 147 ctx = damon_new_ctx(); 148 if (!ctx) 149 return NULL; 150 attrs = (struct damon_attrs) { 151 .sample_interval = 5 * USEC_PER_MSEC, 152 .aggr_interval = 100 * USEC_PER_MSEC, 153 .ops_update_interval = 60 * USEC_PER_MSEC * MSEC_PER_SEC, 154 .min_nr_regions = 10, 155 .max_nr_regions = 1000, 156 }; 157 /* 158 * auto-tune sampling and aggregation interval aiming 4% DAMON-observed 159 * accesses ratio, keeping sampling interval in [5ms, 10s] range. 160 */ 161 attrs.intervals_goal = (struct damon_intervals_goal) { 162 .access_bp = 400, .aggrs = 3, 163 .min_sample_us = 5000, .max_sample_us = 10000000, 164 }; 165 if (damon_set_attrs(ctx, &attrs)) 166 goto free_out; 167 168 /* 169 * auto-tune sampling and aggregation interval aiming 4% DAMON-observed 170 * accesses ratio, keeping sampling interval in [5ms, 10s] range. 171 */ 172 ctx->attrs.intervals_goal = (struct damon_intervals_goal) { 173 .access_bp = 400, .aggrs = 3, 174 .min_sample_us = 5000, .max_sample_us = 10000000, 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 goto free_out; 185 ctx->callback.after_aggregation = damon_stat_after_aggregation; 186 return ctx; 187 free_out: 188 damon_destroy_ctx(ctx); 189 return NULL; 190 } 191 192 static int damon_stat_start(void) 193 { 194 damon_stat_context = damon_stat_build_ctx(); 195 if (!damon_stat_context) 196 return -ENOMEM; 197 return damon_start(&damon_stat_context, 1, true); 198 } 199 200 static void damon_stat_stop(void) 201 { 202 damon_stop(&damon_stat_context, 1); 203 damon_destroy_ctx(damon_stat_context); 204 } 205 206 static bool damon_stat_init_called; 207 208 static int damon_stat_enabled_store( 209 const char *val, const struct kernel_param *kp) 210 { 211 bool is_enabled = enabled; 212 int err; 213 214 err = kstrtobool(val, &enabled); 215 if (err) 216 return err; 217 218 if (is_enabled == enabled) 219 return 0; 220 221 if (!damon_stat_init_called) 222 /* 223 * probably called from command line parsing (parse_args()). 224 * Cannot call damon_new_ctx(). Let damon_stat_init() handle. 225 */ 226 return 0; 227 228 if (enabled) { 229 err = damon_stat_start(); 230 if (err) 231 enabled = false; 232 return err; 233 } 234 damon_stat_stop(); 235 return 0; 236 } 237 238 static int __init damon_stat_init(void) 239 { 240 int err = 0; 241 242 damon_stat_init_called = true; 243 244 /* probably set via command line */ 245 if (enabled) 246 err = damon_stat_start(); 247 248 if (err && enabled) 249 enabled = false; 250 return err; 251 } 252 253 module_init(damon_stat_init); 254