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 static struct damos_watermarks damon_reclaim_wmarks = { 66 .metric = DAMOS_WMARK_FREE_MEM_RATE, 67 .interval = 5000000, /* 5 seconds */ 68 .high = 500, /* 50 percent */ 69 .mid = 400, /* 40 percent */ 70 .low = 200, /* 20 percent */ 71 }; 72 DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_reclaim_wmarks); 73 74 static struct damon_attrs damon_reclaim_mon_attrs = { 75 .sample_interval = 5000, /* 5 ms */ 76 .aggr_interval = 100000, /* 100 ms */ 77 .ops_update_interval = 0, 78 .min_nr_regions = 10, 79 .max_nr_regions = 1000, 80 }; 81 DEFINE_DAMON_MODULES_MON_ATTRS_PARAMS(damon_reclaim_mon_attrs); 82 83 /* 84 * Start of the target memory region in physical address. 85 * 86 * The start physical address of memory region that DAMON_RECLAIM will do work 87 * against. By default, biggest System RAM is used as the region. 88 */ 89 static unsigned long monitor_region_start __read_mostly; 90 module_param(monitor_region_start, ulong, 0600); 91 92 /* 93 * End of the target memory region in physical address. 94 * 95 * The end physical address of memory region that DAMON_RECLAIM will do work 96 * against. By default, biggest System RAM is used as the region. 97 */ 98 static unsigned long monitor_region_end __read_mostly; 99 module_param(monitor_region_end, ulong, 0600); 100 101 /* 102 * PID of the DAMON thread 103 * 104 * If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread. 105 * Else, -1. 106 */ 107 static int kdamond_pid __read_mostly = -1; 108 module_param(kdamond_pid, int, 0400); 109 110 static struct damos_stat damon_reclaim_stat; 111 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_reclaim_stat, 112 reclaim_tried_regions, reclaimed_regions, quota_exceeds); 113 114 static struct damon_ctx *ctx; 115 static struct damon_target *target; 116 117 static struct damos *damon_reclaim_new_scheme(void) 118 { 119 struct damos_access_pattern pattern = { 120 /* Find regions having PAGE_SIZE or larger size */ 121 .min_sz_region = PAGE_SIZE, 122 .max_sz_region = ULONG_MAX, 123 /* and not accessed at all */ 124 .min_nr_accesses = 0, 125 .max_nr_accesses = 0, 126 /* for min_age or more micro-seconds */ 127 .min_age_region = min_age / 128 damon_reclaim_mon_attrs.aggr_interval, 129 .max_age_region = UINT_MAX, 130 }; 131 132 return damon_new_scheme( 133 &pattern, 134 /* page out those, as soon as found */ 135 DAMOS_PAGEOUT, 136 /* under the quota. */ 137 &damon_reclaim_quota, 138 /* (De)activate this according to the watermarks. */ 139 &damon_reclaim_wmarks); 140 } 141 142 static int damon_reclaim_apply_parameters(void) 143 { 144 struct damos *scheme; 145 int err = 0; 146 147 err = damon_set_attrs(ctx, &damon_reclaim_mon_attrs); 148 if (err) 149 return err; 150 151 /* Will be freed by next 'damon_set_schemes()' below */ 152 scheme = damon_reclaim_new_scheme(); 153 if (!scheme) 154 return -ENOMEM; 155 damon_set_schemes(ctx, &scheme, 1); 156 157 return damon_set_region_biggest_system_ram_default(target, 158 &monitor_region_start, 159 &monitor_region_end); 160 } 161 162 static int damon_reclaim_turn(bool on) 163 { 164 int err; 165 166 if (!on) { 167 err = damon_stop(&ctx, 1); 168 if (!err) 169 kdamond_pid = -1; 170 return err; 171 } 172 173 err = damon_reclaim_apply_parameters(); 174 if (err) 175 return err; 176 177 err = damon_start(&ctx, 1, true); 178 if (err) 179 return err; 180 kdamond_pid = ctx->kdamond->pid; 181 return 0; 182 } 183 184 static int damon_reclaim_enabled_store(const char *val, 185 const struct kernel_param *kp) 186 { 187 bool is_enabled = enabled; 188 bool enable; 189 int err; 190 191 err = kstrtobool(val, &enable); 192 if (err) 193 return err; 194 195 if (is_enabled == enable) 196 return 0; 197 198 /* Called before init function. The function will handle this. */ 199 if (!ctx) 200 goto set_param_out; 201 202 err = damon_reclaim_turn(enable); 203 if (err) 204 return err; 205 206 set_param_out: 207 enabled = enable; 208 return err; 209 } 210 211 static const struct kernel_param_ops enabled_param_ops = { 212 .set = damon_reclaim_enabled_store, 213 .get = param_get_bool, 214 }; 215 216 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600); 217 MODULE_PARM_DESC(enabled, 218 "Enable or disable DAMON_RECLAIM (default: disabled)"); 219 220 static int damon_reclaim_handle_commit_inputs(void) 221 { 222 int err; 223 224 if (!commit_inputs) 225 return 0; 226 227 err = damon_reclaim_apply_parameters(); 228 commit_inputs = false; 229 return err; 230 } 231 232 static int damon_reclaim_after_aggregation(struct damon_ctx *c) 233 { 234 struct damos *s; 235 236 /* update the stats parameter */ 237 damon_for_each_scheme(s, c) 238 damon_reclaim_stat = s->stat; 239 240 return damon_reclaim_handle_commit_inputs(); 241 } 242 243 static int damon_reclaim_after_wmarks_check(struct damon_ctx *c) 244 { 245 return damon_reclaim_handle_commit_inputs(); 246 } 247 248 static int __init damon_reclaim_init(void) 249 { 250 int err = damon_modules_new_paddr_ctx_target(&ctx, &target); 251 252 if (err) 253 return err; 254 255 ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check; 256 ctx->callback.after_aggregation = damon_reclaim_after_aggregation; 257 258 /* 'enabled' has set before this function, probably via command line */ 259 if (enabled) 260 err = damon_reclaim_turn(true); 261 262 return err; 263 } 264 265 module_init(damon_reclaim_init); 266