1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * DAMON-based LRU-lists Sorting 4 * 5 * Author: SeongJae Park <sj@kernel.org> 6 */ 7 8 #define pr_fmt(fmt) "damon-lru-sort: " fmt 9 10 #include <linux/damon.h> 11 #include <linux/kstrtox.h> 12 #include <linux/module.h> 13 14 #include "modules-common.h" 15 16 #ifdef MODULE_PARAM_PREFIX 17 #undef MODULE_PARAM_PREFIX 18 #endif 19 #define MODULE_PARAM_PREFIX "damon_lru_sort." 20 21 /* 22 * Enable or disable DAMON_LRU_SORT. 23 * 24 * You can enable DAMON_LRU_SORT by setting the value of this parameter as 25 * ``Y``. Setting it as ``N`` disables DAMON_LRU_SORT. Note that 26 * DAMON_LRU_SORT could do no real monitoring and LRU-lists sorting due to the 27 * watermarks-based activation condition. Refer to below descriptions for the 28 * watermarks parameter for this. 29 */ 30 static bool enabled __read_mostly; 31 32 /* 33 * Make DAMON_LRU_SORT reads the input parameters again, except ``enabled``. 34 * 35 * Input parameters that updated while DAMON_LRU_SORT is running are not 36 * applied by default. Once this parameter is set as ``Y``, DAMON_LRU_SORT 37 * reads values of parametrs except ``enabled`` again. Once the re-reading is 38 * done, this parameter is set as ``N``. If invalid parameters are found while 39 * the re-reading, DAMON_LRU_SORT will be disabled. 40 */ 41 static bool commit_inputs __read_mostly; 42 module_param(commit_inputs, bool, 0600); 43 44 /* 45 * Access frequency threshold for hot memory regions identification in permil. 46 * 47 * If a memory region is accessed in frequency of this or higher, 48 * DAMON_LRU_SORT identifies the region as hot, and mark it as accessed on the 49 * LRU list, so that it could not be reclaimed under memory pressure. 50% by 50 * default. 51 */ 52 static unsigned long hot_thres_access_freq = 500; 53 module_param(hot_thres_access_freq, ulong, 0600); 54 55 /* 56 * Time threshold for cold memory regions identification in microseconds. 57 * 58 * If a memory region is not accessed for this or longer time, DAMON_LRU_SORT 59 * identifies the region as cold, and mark it as unaccessed on the LRU list, so 60 * that it could be reclaimed first under memory pressure. 120 seconds by 61 * default. 62 */ 63 static unsigned long cold_min_age __read_mostly = 120000000; 64 module_param(cold_min_age, ulong, 0600); 65 66 static struct damos_quota damon_lru_sort_quota = { 67 /* Use up to 10 ms per 1 sec, by default */ 68 .ms = 10, 69 .sz = 0, 70 .reset_interval = 1000, 71 /* Within the quota, mark hotter regions accessed first. */ 72 .weight_sz = 0, 73 .weight_nr_accesses = 1, 74 .weight_age = 0, 75 }; 76 DEFINE_DAMON_MODULES_DAMOS_TIME_QUOTA(damon_lru_sort_quota); 77 78 static struct damos_watermarks damon_lru_sort_wmarks = { 79 .metric = DAMOS_WMARK_FREE_MEM_RATE, 80 .interval = 5000000, /* 5 seconds */ 81 .high = 200, /* 20 percent */ 82 .mid = 150, /* 15 percent */ 83 .low = 50, /* 5 percent */ 84 }; 85 DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_lru_sort_wmarks); 86 87 static struct damon_attrs damon_lru_sort_mon_attrs = { 88 .sample_interval = 5000, /* 5 ms */ 89 .aggr_interval = 100000, /* 100 ms */ 90 .ops_update_interval = 0, 91 .min_nr_regions = 10, 92 .max_nr_regions = 1000, 93 }; 94 DEFINE_DAMON_MODULES_MON_ATTRS_PARAMS(damon_lru_sort_mon_attrs); 95 96 /* 97 * Start of the target memory region in physical address. 98 * 99 * The start physical address of memory region that DAMON_LRU_SORT will do work 100 * against. By default, biggest System RAM is used as the region. 101 */ 102 static unsigned long monitor_region_start __read_mostly; 103 module_param(monitor_region_start, ulong, 0600); 104 105 /* 106 * End of the target memory region in physical address. 107 * 108 * The end physical address of memory region that DAMON_LRU_SORT will do work 109 * against. By default, biggest System RAM is used as the region. 110 */ 111 static unsigned long monitor_region_end __read_mostly; 112 module_param(monitor_region_end, ulong, 0600); 113 114 /* 115 * PID of the DAMON thread 116 * 117 * If DAMON_LRU_SORT is enabled, this becomes the PID of the worker thread. 118 * Else, -1. 119 */ 120 static int kdamond_pid __read_mostly = -1; 121 module_param(kdamond_pid, int, 0400); 122 123 static struct damos_stat damon_lru_sort_hot_stat; 124 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_lru_sort_hot_stat, 125 lru_sort_tried_hot_regions, lru_sorted_hot_regions, 126 hot_quota_exceeds); 127 128 static struct damos_stat damon_lru_sort_cold_stat; 129 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_lru_sort_cold_stat, 130 lru_sort_tried_cold_regions, lru_sorted_cold_regions, 131 cold_quota_exceeds); 132 133 static struct damos_access_pattern damon_lru_sort_stub_pattern = { 134 /* Find regions having PAGE_SIZE or larger size */ 135 .min_sz_region = PAGE_SIZE, 136 .max_sz_region = ULONG_MAX, 137 /* no matter its access frequency */ 138 .min_nr_accesses = 0, 139 .max_nr_accesses = UINT_MAX, 140 /* no matter its age */ 141 .min_age_region = 0, 142 .max_age_region = UINT_MAX, 143 }; 144 145 static struct damon_ctx *ctx; 146 static struct damon_target *target; 147 148 static struct damos *damon_lru_sort_new_scheme( 149 struct damos_access_pattern *pattern, enum damos_action action) 150 { 151 struct damos_quota quota = damon_lru_sort_quota; 152 153 /* Use half of total quota for hot/cold pages sorting */ 154 quota.ms = quota.ms / 2; 155 156 return damon_new_scheme( 157 /* find the pattern, and */ 158 pattern, 159 /* (de)prioritize on LRU-lists */ 160 action, 161 /* for each aggregation interval */ 162 0, 163 /* under the quota. */ 164 "a, 165 /* (De)activate this according to the watermarks. */ 166 &damon_lru_sort_wmarks); 167 } 168 169 /* Create a DAMON-based operation scheme for hot memory regions */ 170 static struct damos *damon_lru_sort_new_hot_scheme(unsigned int hot_thres) 171 { 172 struct damos_access_pattern pattern = damon_lru_sort_stub_pattern; 173 174 pattern.min_nr_accesses = hot_thres; 175 return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_PRIO); 176 } 177 178 /* Create a DAMON-based operation scheme for cold memory regions */ 179 static struct damos *damon_lru_sort_new_cold_scheme(unsigned int cold_thres) 180 { 181 struct damos_access_pattern pattern = damon_lru_sort_stub_pattern; 182 183 pattern.max_nr_accesses = 0; 184 pattern.min_age_region = cold_thres; 185 return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_DEPRIO); 186 } 187 188 static int damon_lru_sort_apply_parameters(void) 189 { 190 struct damos *scheme; 191 unsigned int hot_thres, cold_thres; 192 int err = 0; 193 194 err = damon_set_attrs(ctx, &damon_lru_sort_mon_attrs); 195 if (err) 196 return err; 197 198 hot_thres = damon_max_nr_accesses(&damon_lru_sort_mon_attrs) * 199 hot_thres_access_freq / 1000; 200 scheme = damon_lru_sort_new_hot_scheme(hot_thres); 201 if (!scheme) 202 return -ENOMEM; 203 damon_set_schemes(ctx, &scheme, 1); 204 205 cold_thres = cold_min_age / damon_lru_sort_mon_attrs.aggr_interval; 206 scheme = damon_lru_sort_new_cold_scheme(cold_thres); 207 if (!scheme) 208 return -ENOMEM; 209 damon_add_scheme(ctx, scheme); 210 211 return damon_set_region_biggest_system_ram_default(target, 212 &monitor_region_start, 213 &monitor_region_end); 214 } 215 216 static int damon_lru_sort_turn(bool on) 217 { 218 int err; 219 220 if (!on) { 221 err = damon_stop(&ctx, 1); 222 if (!err) 223 kdamond_pid = -1; 224 return err; 225 } 226 227 err = damon_lru_sort_apply_parameters(); 228 if (err) 229 return err; 230 231 err = damon_start(&ctx, 1, true); 232 if (err) 233 return err; 234 kdamond_pid = ctx->kdamond->pid; 235 return 0; 236 } 237 238 static int damon_lru_sort_enabled_store(const char *val, 239 const struct kernel_param *kp) 240 { 241 bool is_enabled = enabled; 242 bool enable; 243 int err; 244 245 err = kstrtobool(val, &enable); 246 if (err) 247 return err; 248 249 if (is_enabled == enable) 250 return 0; 251 252 /* Called before init function. The function will handle this. */ 253 if (!ctx) 254 goto set_param_out; 255 256 err = damon_lru_sort_turn(enable); 257 if (err) 258 return err; 259 260 set_param_out: 261 enabled = enable; 262 return err; 263 } 264 265 static const struct kernel_param_ops enabled_param_ops = { 266 .set = damon_lru_sort_enabled_store, 267 .get = param_get_bool, 268 }; 269 270 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600); 271 MODULE_PARM_DESC(enabled, 272 "Enable or disable DAMON_LRU_SORT (default: disabled)"); 273 274 static int damon_lru_sort_handle_commit_inputs(void) 275 { 276 int err; 277 278 if (!commit_inputs) 279 return 0; 280 281 err = damon_lru_sort_apply_parameters(); 282 commit_inputs = false; 283 return err; 284 } 285 286 static int damon_lru_sort_after_aggregation(struct damon_ctx *c) 287 { 288 struct damos *s; 289 290 /* update the stats parameter */ 291 damon_for_each_scheme(s, c) { 292 if (s->action == DAMOS_LRU_PRIO) 293 damon_lru_sort_hot_stat = s->stat; 294 else if (s->action == DAMOS_LRU_DEPRIO) 295 damon_lru_sort_cold_stat = s->stat; 296 } 297 298 return damon_lru_sort_handle_commit_inputs(); 299 } 300 301 static int damon_lru_sort_after_wmarks_check(struct damon_ctx *c) 302 { 303 return damon_lru_sort_handle_commit_inputs(); 304 } 305 306 static int __init damon_lru_sort_init(void) 307 { 308 int err = damon_modules_new_paddr_ctx_target(&ctx, &target); 309 310 if (err) 311 return err; 312 313 ctx->callback.after_wmarks_check = damon_lru_sort_after_wmarks_check; 314 ctx->callback.after_aggregation = damon_lru_sort_after_aggregation; 315 316 /* 'enabled' has set before this function, probably via command line */ 317 if (enabled) 318 err = damon_lru_sort_turn(true); 319 320 return err; 321 } 322 323 module_init(damon_lru_sort_init); 324