1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * DAMON-based page reclamation 4 * 5 * Author: SeongJae Park <sj@kernel.org> 6 */ 7 8 #define pr_fmt(fmt) "damon-reclaim: " 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_reclaim." 20 21 /* 22 * Enable or disable DAMON_RECLAIM. 23 * 24 * You can enable DAMON_RCLAIM by setting the value of this parameter as ``Y``. 25 * Setting it as ``N`` disables DAMON_RECLAIM. Note that DAMON_RECLAIM could 26 * do no real monitoring and reclamation due to the watermarks-based activation 27 * condition. Refer to below descriptions for the watermarks parameter for 28 * this. 29 */ 30 static bool enabled __read_mostly; 31 32 /* 33 * Make DAMON_RECLAIM reads the input parameters again, except ``enabled``. 34 * 35 * Input parameters that updated while DAMON_RECLAIM is running are not applied 36 * by default. Once this parameter is set as ``Y``, DAMON_RECLAIM reads values 37 * of parametrs except ``enabled`` again. Once the re-reading is done, this 38 * parameter is set as ``N``. If invalid parameters are found while the 39 * re-reading, DAMON_RECLAIM will be disabled. 40 */ 41 static bool commit_inputs __read_mostly; 42 module_param(commit_inputs, bool, 0600); 43 44 /* 45 * Time threshold for cold memory regions identification in microseconds. 46 * 47 * If a memory region is not accessed for this or longer time, DAMON_RECLAIM 48 * identifies the region as cold, and reclaims. 120 seconds by default. 49 */ 50 static unsigned long min_age __read_mostly = 120000000; 51 module_param(min_age, ulong, 0600); 52 53 static struct damos_quota damon_reclaim_quota = { 54 /* use up to 10 ms time, reclaim up to 128 MiB per 1 sec by default */ 55 .ms = 10, 56 .sz = 128 * 1024 * 1024, 57 .reset_interval = 1000, 58 /* Within the quota, page out older regions first. */ 59 .weight_sz = 0, 60 .weight_nr_accesses = 0, 61 .weight_age = 1 62 }; 63 DEFINE_DAMON_MODULES_DAMOS_QUOTAS(damon_reclaim_quota); 64 65 /* 66 * Desired level of memory pressure-stall time in microseconds. 67 * 68 * While keeping the caps that set by other quotas, DAMON_RECLAIM automatically 69 * increases and decreases the effective level of the quota aiming this level of 70 * memory pressure is incurred. System-wide ``some`` memory PSI in microseconds 71 * per quota reset interval (``quota_reset_interval_ms``) is collected and 72 * compared to this value to see if the aim is satisfied. Value zero means 73 * disabling this auto-tuning feature. 74 * 75 * Disabled by default. 76 */ 77 static unsigned long quota_mem_pressure_us __read_mostly; 78 module_param(quota_mem_pressure_us, ulong, 0600); 79 80 /* 81 * User-specifiable feedback for auto-tuning of the effective quota. 82 * 83 * While keeping the caps that set by other quotas, DAMON_RECLAIM automatically 84 * increases and decreases the effective level of the quota aiming receiving this 85 * feedback of value ``10,000`` from the user. DAMON_RECLAIM assumes the feedback 86 * value and the quota are positively proportional. Value zero means disabling 87 * this auto-tuning feature. 88 * 89 * Disabled by default. 90 * 91 */ 92 static unsigned long quota_autotune_feedback __read_mostly; 93 module_param(quota_autotune_feedback, ulong, 0600); 94 95 static struct damos_watermarks damon_reclaim_wmarks = { 96 .metric = DAMOS_WMARK_FREE_MEM_RATE, 97 .interval = 5000000, /* 5 seconds */ 98 .high = 500, /* 50 percent */ 99 .mid = 400, /* 40 percent */ 100 .low = 200, /* 20 percent */ 101 }; 102 DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_reclaim_wmarks); 103 104 static struct damon_attrs damon_reclaim_mon_attrs = { 105 .sample_interval = 5000, /* 5 ms */ 106 .aggr_interval = 100000, /* 100 ms */ 107 .ops_update_interval = 0, 108 .min_nr_regions = 10, 109 .max_nr_regions = 1000, 110 }; 111 DEFINE_DAMON_MODULES_MON_ATTRS_PARAMS(damon_reclaim_mon_attrs); 112 113 /* 114 * Start of the target memory region in physical address. 115 * 116 * The start physical address of memory region that DAMON_RECLAIM will do work 117 * against. By default, biggest System RAM is used as the region. 118 */ 119 static unsigned long monitor_region_start __read_mostly; 120 module_param(monitor_region_start, ulong, 0600); 121 122 /* 123 * End of the target memory region in physical address. 124 * 125 * The end physical address of memory region that DAMON_RECLAIM will do work 126 * against. By default, biggest System RAM is used as the region. 127 */ 128 static unsigned long monitor_region_end __read_mostly; 129 module_param(monitor_region_end, ulong, 0600); 130 131 /* 132 * Scale factor for DAMON_RECLAIM to ops address conversion. 133 * 134 * This parameter must not be set to 0. 135 */ 136 static unsigned long addr_unit __read_mostly = 1; 137 138 /* 139 * Skip anonymous pages reclamation. 140 * 141 * If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous 142 * pages. By default, ``N``. 143 */ 144 static bool skip_anon __read_mostly; 145 module_param(skip_anon, bool, 0600); 146 147 /* 148 * PID of the DAMON thread 149 * 150 * If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread. 151 * Else, -1. 152 */ 153 static int kdamond_pid __read_mostly = -1; 154 module_param(kdamond_pid, int, 0400); 155 156 static struct damos_stat damon_reclaim_stat; 157 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_reclaim_stat, 158 reclaim_tried_regions, reclaimed_regions, quota_exceeds); 159 160 static struct damon_ctx *ctx; 161 static struct damon_target *target; 162 163 static struct damos *damon_reclaim_new_scheme(void) 164 { 165 struct damos_access_pattern pattern = { 166 /* Find regions having PAGE_SIZE or larger size */ 167 .min_sz_region = PAGE_SIZE, 168 .max_sz_region = ULONG_MAX, 169 /* and not accessed at all */ 170 .min_nr_accesses = 0, 171 .max_nr_accesses = 0, 172 /* for min_age or more micro-seconds */ 173 .min_age_region = min_age / 174 damon_reclaim_mon_attrs.aggr_interval, 175 .max_age_region = UINT_MAX, 176 }; 177 178 return damon_new_scheme( 179 &pattern, 180 /* page out those, as soon as found */ 181 DAMOS_PAGEOUT, 182 /* for each aggregation interval */ 183 0, 184 /* under the quota. */ 185 &damon_reclaim_quota, 186 /* (De)activate this according to the watermarks. */ 187 &damon_reclaim_wmarks, 188 NUMA_NO_NODE); 189 } 190 191 static int damon_reclaim_apply_parameters(void) 192 { 193 struct damon_ctx *param_ctx; 194 struct damon_target *param_target; 195 struct damos *scheme; 196 struct damos_quota_goal *goal; 197 struct damos_filter *filter; 198 int err; 199 200 err = damon_modules_new_paddr_ctx_target(¶m_ctx, ¶m_target); 201 if (err) 202 return err; 203 204 /* 205 * If monitor_region_start/end are unset, always silently 206 * reset addr_unit to 1. 207 */ 208 if (!monitor_region_start && !monitor_region_end) 209 addr_unit = 1; 210 param_ctx->addr_unit = addr_unit; 211 param_ctx->min_sz_region = max(DAMON_MIN_REGION / addr_unit, 1); 212 213 if (!damon_reclaim_mon_attrs.aggr_interval) { 214 err = -EINVAL; 215 goto out; 216 } 217 218 err = damon_set_attrs(param_ctx, &damon_reclaim_mon_attrs); 219 if (err) 220 goto out; 221 222 err = -ENOMEM; 223 scheme = damon_reclaim_new_scheme(); 224 if (!scheme) 225 goto out; 226 damon_set_schemes(param_ctx, &scheme, 1); 227 228 if (quota_mem_pressure_us) { 229 goal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US, 230 quota_mem_pressure_us); 231 if (!goal) 232 goto out; 233 damos_add_quota_goal(&scheme->quota, goal); 234 } 235 236 if (quota_autotune_feedback) { 237 goal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, 10000); 238 if (!goal) 239 goto out; 240 goal->current_value = quota_autotune_feedback; 241 damos_add_quota_goal(&scheme->quota, goal); 242 } 243 244 if (skip_anon) { 245 filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true, false); 246 if (!filter) 247 goto out; 248 damos_add_filter(scheme, filter); 249 } 250 251 err = damon_set_region_biggest_system_ram_default(param_target, 252 &monitor_region_start, 253 &monitor_region_end); 254 if (err) 255 goto out; 256 err = damon_commit_ctx(ctx, param_ctx); 257 out: 258 damon_destroy_ctx(param_ctx); 259 return err; 260 } 261 262 static int damon_reclaim_handle_commit_inputs(void) 263 { 264 int err; 265 266 if (!commit_inputs) 267 return 0; 268 269 err = damon_reclaim_apply_parameters(); 270 commit_inputs = false; 271 return err; 272 } 273 274 static int damon_reclaim_damon_call_fn(void *arg) 275 { 276 struct damon_ctx *c = arg; 277 struct damos *s; 278 279 /* update the stats parameter */ 280 damon_for_each_scheme(s, c) 281 damon_reclaim_stat = s->stat; 282 283 return damon_reclaim_handle_commit_inputs(); 284 } 285 286 static struct damon_call_control call_control = { 287 .fn = damon_reclaim_damon_call_fn, 288 .repeat = true, 289 }; 290 291 static int damon_reclaim_turn(bool on) 292 { 293 int err; 294 295 if (!on) { 296 err = damon_stop(&ctx, 1); 297 if (!err) 298 kdamond_pid = -1; 299 return err; 300 } 301 302 err = damon_reclaim_apply_parameters(); 303 if (err) 304 return err; 305 306 err = damon_start(&ctx, 1, true); 307 if (err) 308 return err; 309 kdamond_pid = ctx->kdamond->pid; 310 return damon_call(ctx, &call_control); 311 } 312 313 static int damon_reclaim_addr_unit_store(const char *val, 314 const struct kernel_param *kp) 315 { 316 unsigned long input_addr_unit; 317 int err = kstrtoul(val, 0, &input_addr_unit); 318 319 if (err) 320 return err; 321 if (!input_addr_unit) 322 return -EINVAL; 323 324 addr_unit = input_addr_unit; 325 return 0; 326 } 327 328 static const struct kernel_param_ops addr_unit_param_ops = { 329 .set = damon_reclaim_addr_unit_store, 330 .get = param_get_ulong, 331 }; 332 333 module_param_cb(addr_unit, &addr_unit_param_ops, &addr_unit, 0600); 334 MODULE_PARM_DESC(addr_unit, 335 "Scale factor for DAMON_RECLAIM to ops address conversion (default: 1)"); 336 337 static int damon_reclaim_enabled_store(const char *val, 338 const struct kernel_param *kp) 339 { 340 bool is_enabled = enabled; 341 bool enable; 342 int err; 343 344 err = kstrtobool(val, &enable); 345 if (err) 346 return err; 347 348 if (is_enabled == enable) 349 return 0; 350 351 /* Called before init function. The function will handle this. */ 352 if (!damon_initialized()) 353 goto set_param_out; 354 355 err = damon_reclaim_turn(enable); 356 if (err) 357 return err; 358 359 set_param_out: 360 enabled = enable; 361 return err; 362 } 363 364 static const struct kernel_param_ops enabled_param_ops = { 365 .set = damon_reclaim_enabled_store, 366 .get = param_get_bool, 367 }; 368 369 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600); 370 MODULE_PARM_DESC(enabled, 371 "Enable or disable DAMON_RECLAIM (default: disabled)"); 372 373 static int __init damon_reclaim_init(void) 374 { 375 int err; 376 377 if (!damon_initialized()) { 378 err = -ENOMEM; 379 goto out; 380 } 381 err = damon_modules_new_paddr_ctx_target(&ctx, &target); 382 if (err) 383 goto out; 384 385 call_control.data = ctx; 386 387 /* 'enabled' has set before this function, probably via command line */ 388 if (enabled) 389 err = damon_reclaim_turn(true); 390 391 out: 392 if (err && enabled) 393 enabled = false; 394 return err; 395 } 396 397 module_init(damon_reclaim_init); 398