// SPDX-License-Identifier: GPL-2.0 /* * DAMON-based page reclamation * * Author: SeongJae Park */ #define pr_fmt(fmt) "damon-reclaim: " fmt #include #include #include #include "modules-common.h" #ifdef MODULE_PARAM_PREFIX #undef MODULE_PARAM_PREFIX #endif #define MODULE_PARAM_PREFIX "damon_reclaim." /* * Enable or disable DAMON_RECLAIM. * * You can enable DAMON_RCLAIM by setting the value of this parameter as ``Y``. * Setting it as ``N`` disables DAMON_RECLAIM. Note that DAMON_RECLAIM could * do no real monitoring and reclamation due to the watermarks-based activation * condition. Refer to below descriptions for the watermarks parameter for * this. */ static bool enabled __read_mostly; /* * Make DAMON_RECLAIM reads the input parameters again, except ``enabled``. * * Input parameters that updated while DAMON_RECLAIM is running are not applied * by default. Once this parameter is set as ``Y``, DAMON_RECLAIM reads values * of parametrs except ``enabled`` again. Once the re-reading is done, this * parameter is set as ``N``. If invalid parameters are found while the * re-reading, DAMON_RECLAIM will be disabled. */ static bool commit_inputs __read_mostly; module_param(commit_inputs, bool, 0600); /* * Time threshold for cold memory regions identification in microseconds. * * If a memory region is not accessed for this or longer time, DAMON_RECLAIM * identifies the region as cold, and reclaims. 120 seconds by default. */ static unsigned long min_age __read_mostly = 120000000; module_param(min_age, ulong, 0600); static struct damos_quota damon_reclaim_quota = { /* use up to 10 ms time, reclaim up to 128 MiB per 1 sec by default */ .ms = 10, .sz = 128 * 1024 * 1024, .reset_interval = 1000, /* Within the quota, page out older regions first. */ .weight_sz = 0, .weight_nr_accesses = 0, .weight_age = 1 }; DEFINE_DAMON_MODULES_DAMOS_QUOTAS(damon_reclaim_quota); static struct damos_watermarks damon_reclaim_wmarks = { .metric = DAMOS_WMARK_FREE_MEM_RATE, .interval = 5000000, /* 5 seconds */ .high = 500, /* 50 percent */ .mid = 400, /* 40 percent */ .low = 200, /* 20 percent */ }; DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_reclaim_wmarks); static struct damon_attrs damon_reclaim_mon_attrs = { .sample_interval = 5000, /* 5 ms */ .aggr_interval = 100000, /* 100 ms */ .ops_update_interval = 0, .min_nr_regions = 10, .max_nr_regions = 1000, }; DEFINE_DAMON_MODULES_MON_ATTRS_PARAMS(damon_reclaim_mon_attrs); /* * Start of the target memory region in physical address. * * The start physical address of memory region that DAMON_RECLAIM will do work * against. By default, biggest System RAM is used as the region. */ static unsigned long monitor_region_start __read_mostly; module_param(monitor_region_start, ulong, 0600); /* * End of the target memory region in physical address. * * The end physical address of memory region that DAMON_RECLAIM will do work * against. By default, biggest System RAM is used as the region. */ static unsigned long monitor_region_end __read_mostly; module_param(monitor_region_end, ulong, 0600); /* * PID of the DAMON thread * * If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread. * Else, -1. */ static int kdamond_pid __read_mostly = -1; module_param(kdamond_pid, int, 0400); static struct damos_stat damon_reclaim_stat; DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_reclaim_stat, reclaim_tried_regions, reclaimed_regions, quota_exceeds); static struct damon_ctx *ctx; static struct damon_target *target; static struct damos *damon_reclaim_new_scheme(void) { struct damos_access_pattern pattern = { /* Find regions having PAGE_SIZE or larger size */ .min_sz_region = PAGE_SIZE, .max_sz_region = ULONG_MAX, /* and not accessed at all */ .min_nr_accesses = 0, .max_nr_accesses = 0, /* for min_age or more micro-seconds */ .min_age_region = min_age / damon_reclaim_mon_attrs.aggr_interval, .max_age_region = UINT_MAX, }; return damon_new_scheme( &pattern, /* page out those, as soon as found */ DAMOS_PAGEOUT, /* under the quota. */ &damon_reclaim_quota, /* (De)activate this according to the watermarks. */ &damon_reclaim_wmarks); } static int damon_reclaim_apply_parameters(void) { struct damos *scheme; int err = 0; err = damon_set_attrs(ctx, &damon_reclaim_mon_attrs); if (err) return err; /* Will be freed by next 'damon_set_schemes()' below */ scheme = damon_reclaim_new_scheme(); if (!scheme) return -ENOMEM; damon_set_schemes(ctx, &scheme, 1); return damon_set_region_biggest_system_ram_default(target, &monitor_region_start, &monitor_region_end); } static int damon_reclaim_turn(bool on) { int err; if (!on) { err = damon_stop(&ctx, 1); if (!err) kdamond_pid = -1; return err; } err = damon_reclaim_apply_parameters(); if (err) return err; err = damon_start(&ctx, 1, true); if (err) return err; kdamond_pid = ctx->kdamond->pid; return 0; } static int damon_reclaim_enabled_store(const char *val, const struct kernel_param *kp) { bool is_enabled = enabled; bool enable; int err; err = kstrtobool(val, &enable); if (err) return err; if (is_enabled == enable) return 0; /* Called before init function. The function will handle this. */ if (!ctx) goto set_param_out; err = damon_reclaim_turn(enable); if (err) return err; set_param_out: enabled = enable; return err; } static const struct kernel_param_ops enabled_param_ops = { .set = damon_reclaim_enabled_store, .get = param_get_bool, }; module_param_cb(enabled, &enabled_param_ops, &enabled, 0600); MODULE_PARM_DESC(enabled, "Enable or disable DAMON_RECLAIM (default: disabled)"); static int damon_reclaim_handle_commit_inputs(void) { int err; if (!commit_inputs) return 0; err = damon_reclaim_apply_parameters(); commit_inputs = false; return err; } static int damon_reclaim_after_aggregation(struct damon_ctx *c) { struct damos *s; /* update the stats parameter */ damon_for_each_scheme(s, c) damon_reclaim_stat = s->stat; return damon_reclaim_handle_commit_inputs(); } static int damon_reclaim_after_wmarks_check(struct damon_ctx *c) { return damon_reclaim_handle_commit_inputs(); } static int __init damon_reclaim_init(void) { int err = damon_modules_new_paddr_ctx_target(&ctx, &target); if (err) return err; ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check; ctx->callback.after_aggregation = damon_reclaim_after_aggregation; /* 'enabled' has set before this function, probably via command line */ if (enabled) err = damon_reclaim_turn(true); return err; } module_init(damon_reclaim_init);