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 * Skip anonymous pages reclamation. 133 * 134 * If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous 135 * pages. By default, ``N``. 136 */ 137 static bool skip_anon __read_mostly; 138 module_param(skip_anon, bool, 0600); 139 140 /* 141 * PID of the DAMON thread 142 * 143 * If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread. 144 * Else, -1. 145 */ 146 static int kdamond_pid __read_mostly = -1; 147 module_param(kdamond_pid, int, 0400); 148 149 static struct damos_stat damon_reclaim_stat; 150 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_reclaim_stat, 151 reclaim_tried_regions, reclaimed_regions, quota_exceeds); 152 153 static struct damon_ctx *ctx; 154 static struct damon_target *target; 155 156 static struct damos *damon_reclaim_new_scheme(void) 157 { 158 struct damos_access_pattern pattern = { 159 /* Find regions having PAGE_SIZE or larger size */ 160 .min_sz_region = PAGE_SIZE, 161 .max_sz_region = ULONG_MAX, 162 /* and not accessed at all */ 163 .min_nr_accesses = 0, 164 .max_nr_accesses = 0, 165 /* for min_age or more micro-seconds */ 166 .min_age_region = min_age / 167 damon_reclaim_mon_attrs.aggr_interval, 168 .max_age_region = UINT_MAX, 169 }; 170 171 return damon_new_scheme( 172 &pattern, 173 /* page out those, as soon as found */ 174 DAMOS_PAGEOUT, 175 /* for each aggregation interval */ 176 0, 177 /* under the quota. */ 178 &damon_reclaim_quota, 179 /* (De)activate this according to the watermarks. */ 180 &damon_reclaim_wmarks, 181 NUMA_NO_NODE); 182 } 183 184 static int damon_reclaim_apply_parameters(void) 185 { 186 struct damon_ctx *param_ctx; 187 struct damon_target *param_target; 188 struct damos *scheme; 189 struct damos_quota_goal *goal; 190 struct damos_filter *filter; 191 int err; 192 193 err = damon_modules_new_paddr_ctx_target(¶m_ctx, ¶m_target); 194 if (err) 195 return err; 196 197 err = damon_set_attrs(ctx, &damon_reclaim_mon_attrs); 198 if (err) 199 goto out; 200 201 err = -ENOMEM; 202 scheme = damon_reclaim_new_scheme(); 203 if (!scheme) 204 goto out; 205 damon_set_schemes(ctx, &scheme, 1); 206 207 if (quota_mem_pressure_us) { 208 goal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US, 209 quota_mem_pressure_us); 210 if (!goal) 211 goto out; 212 damos_add_quota_goal(&scheme->quota, goal); 213 } 214 215 if (quota_autotune_feedback) { 216 goal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, 10000); 217 if (!goal) 218 goto out; 219 goal->current_value = quota_autotune_feedback; 220 damos_add_quota_goal(&scheme->quota, goal); 221 } 222 223 if (skip_anon) { 224 filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true); 225 if (!filter) 226 goto out; 227 damos_add_filter(scheme, filter); 228 } 229 230 err = damon_set_region_biggest_system_ram_default(param_target, 231 &monitor_region_start, 232 &monitor_region_end); 233 if (err) 234 goto out; 235 err = damon_commit_ctx(ctx, param_ctx); 236 out: 237 damon_destroy_ctx(param_ctx); 238 return err; 239 } 240 241 static int damon_reclaim_turn(bool on) 242 { 243 int err; 244 245 if (!on) { 246 err = damon_stop(&ctx, 1); 247 if (!err) 248 kdamond_pid = -1; 249 return err; 250 } 251 252 err = damon_reclaim_apply_parameters(); 253 if (err) 254 return err; 255 256 err = damon_start(&ctx, 1, true); 257 if (err) 258 return err; 259 kdamond_pid = ctx->kdamond->pid; 260 return 0; 261 } 262 263 static int damon_reclaim_enabled_store(const char *val, 264 const struct kernel_param *kp) 265 { 266 bool is_enabled = enabled; 267 bool enable; 268 int err; 269 270 err = kstrtobool(val, &enable); 271 if (err) 272 return err; 273 274 if (is_enabled == enable) 275 return 0; 276 277 /* Called before init function. The function will handle this. */ 278 if (!ctx) 279 goto set_param_out; 280 281 err = damon_reclaim_turn(enable); 282 if (err) 283 return err; 284 285 set_param_out: 286 enabled = enable; 287 return err; 288 } 289 290 static const struct kernel_param_ops enabled_param_ops = { 291 .set = damon_reclaim_enabled_store, 292 .get = param_get_bool, 293 }; 294 295 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600); 296 MODULE_PARM_DESC(enabled, 297 "Enable or disable DAMON_RECLAIM (default: disabled)"); 298 299 static int damon_reclaim_handle_commit_inputs(void) 300 { 301 int err; 302 303 if (!commit_inputs) 304 return 0; 305 306 err = damon_reclaim_apply_parameters(); 307 commit_inputs = false; 308 return err; 309 } 310 311 static int damon_reclaim_after_aggregation(struct damon_ctx *c) 312 { 313 struct damos *s; 314 315 /* update the stats parameter */ 316 damon_for_each_scheme(s, c) 317 damon_reclaim_stat = s->stat; 318 319 return damon_reclaim_handle_commit_inputs(); 320 } 321 322 static int damon_reclaim_after_wmarks_check(struct damon_ctx *c) 323 { 324 return damon_reclaim_handle_commit_inputs(); 325 } 326 327 static int __init damon_reclaim_init(void) 328 { 329 int err = damon_modules_new_paddr_ctx_target(&ctx, &target); 330 331 if (err) 332 return err; 333 334 ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check; 335 ctx->callback.after_aggregation = damon_reclaim_after_aggregation; 336 337 /* 'enabled' has set before this function, probably via command line */ 338 if (enabled) 339 err = damon_reclaim_turn(true); 340 341 return err; 342 } 343 344 module_init(damon_reclaim_init); 345