// SPDX-License-Identifier: GPL-2.0 /* * DAMON-based LRU-lists Sorting * * Author: SeongJae Park */ #define pr_fmt(fmt) "damon-lru-sort: " fmt #include #include #include #include #include #ifdef MODULE_PARAM_PREFIX #undef MODULE_PARAM_PREFIX #endif #define MODULE_PARAM_PREFIX "damon_lru_sort." /* * Enable or disable DAMON_LRU_SORT. * * You can enable DAMON_LRU_SORT by setting the value of this parameter as * ``Y``. Setting it as ``N`` disables DAMON_LRU_SORT. Note that * DAMON_LRU_SORT could do no real monitoring and LRU-lists sorting due to the * watermarks-based activation condition. Refer to below descriptions for the * watermarks parameter for this. */ static bool enabled __read_mostly; /* * Make DAMON_LRU_SORT reads the input parameters again, except ``enabled``. * * Input parameters that updated while DAMON_LRU_SORT is running are not * applied by default. Once this parameter is set as ``Y``, DAMON_LRU_SORT * 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_LRU_SORT will be disabled. */ static bool commit_inputs __read_mostly; module_param(commit_inputs, bool, 0600); /* * Access frequency threshold for hot memory regions identification in permil. * * If a memory region is accessed in frequency of this or higher, * DAMON_LRU_SORT identifies the region as hot, and mark it as accessed on the * LRU list, so that it could not be reclaimed under memory pressure. 50% by * default. */ static unsigned long hot_thres_access_freq = 500; module_param(hot_thres_access_freq, ulong, 0600); /* * Time threshold for cold memory regions identification in microseconds. * * If a memory region is not accessed for this or longer time, DAMON_LRU_SORT * identifies the region as cold, and mark it as unaccessed on the LRU list, so * that it could be reclaimed first under memory pressure. 120 seconds by * default. */ static unsigned long cold_min_age __read_mostly = 120000000; module_param(cold_min_age, ulong, 0600); /* * Limit of time for trying the LRU lists sorting in milliseconds. * * DAMON_LRU_SORT tries to use only up to this time within a time window * (quota_reset_interval_ms) for trying LRU lists sorting. This can be used * for limiting CPU consumption of DAMON_LRU_SORT. If the value is zero, the * limit is disabled. * * 10 ms by default. */ static unsigned long quota_ms __read_mostly = 10; module_param(quota_ms, ulong, 0600); /* * The time quota charge reset interval in milliseconds. * * The charge reset interval for the quota of time (quota_ms). That is, * DAMON_LRU_SORT does not try LRU-lists sorting for more than quota_ms * milliseconds or quota_sz bytes within quota_reset_interval_ms milliseconds. * * 1 second by default. */ static unsigned long quota_reset_interval_ms __read_mostly = 1000; module_param(quota_reset_interval_ms, ulong, 0600); /* * The watermarks check time interval in microseconds. * * Minimal time to wait before checking the watermarks, when DAMON_LRU_SORT is * enabled but inactive due to its watermarks rule. 5 seconds by default. */ static unsigned long wmarks_interval __read_mostly = 5000000; module_param(wmarks_interval, ulong, 0600); /* * Free memory rate (per thousand) for the high watermark. * * If free memory of the system in bytes per thousand bytes is higher than * this, DAMON_LRU_SORT becomes inactive, so it does nothing but periodically * checks the watermarks. 200 (20%) by default. */ static unsigned long wmarks_high __read_mostly = 200; module_param(wmarks_high, ulong, 0600); /* * Free memory rate (per thousand) for the middle watermark. * * If free memory of the system in bytes per thousand bytes is between this and * the low watermark, DAMON_LRU_SORT becomes active, so starts the monitoring * and the LRU-lists sorting. 150 (15%) by default. */ static unsigned long wmarks_mid __read_mostly = 150; module_param(wmarks_mid, ulong, 0600); /* * Free memory rate (per thousand) for the low watermark. * * If free memory of the system in bytes per thousand bytes is lower than this, * DAMON_LRU_SORT becomes inactive, so it does nothing but periodically checks * the watermarks. 50 (5%) by default. */ static unsigned long wmarks_low __read_mostly = 50; module_param(wmarks_low, ulong, 0600); /* * Sampling interval for the monitoring in microseconds. * * The sampling interval of DAMON for the hot/cold memory monitoring. Please * refer to the DAMON documentation for more detail. 5 ms by default. */ static unsigned long sample_interval __read_mostly = 5000; module_param(sample_interval, ulong, 0600); /* * Aggregation interval for the monitoring in microseconds. * * The aggregation interval of DAMON for the hot/cold memory monitoring. * Please refer to the DAMON documentation for more detail. 100 ms by default. */ static unsigned long aggr_interval __read_mostly = 100000; module_param(aggr_interval, ulong, 0600); /* * Minimum number of monitoring regions. * * The minimal number of monitoring regions of DAMON for the hot/cold memory * monitoring. This can be used to set lower-bound of the monitoring quality. * But, setting this too high could result in increased monitoring overhead. * Please refer to the DAMON documentation for more detail. 10 by default. */ static unsigned long min_nr_regions __read_mostly = 10; module_param(min_nr_regions, ulong, 0600); /* * Maximum number of monitoring regions. * * The maximum number of monitoring regions of DAMON for the hot/cold memory * monitoring. This can be used to set upper-bound of the monitoring overhead. * However, setting this too low could result in bad monitoring quality. * Please refer to the DAMON documentation for more detail. 1000 by default. */ static unsigned long max_nr_regions __read_mostly = 1000; module_param(max_nr_regions, ulong, 0600); /* * Start of the target memory region in physical address. * * The start physical address of memory region that DAMON_LRU_SORT 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_LRU_SORT 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_LRU_SORT 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); /* * Number of hot memory regions that tried to be LRU-sorted. */ static unsigned long nr_lru_sort_tried_hot_regions __read_mostly; module_param(nr_lru_sort_tried_hot_regions, ulong, 0400); /* * Total bytes of hot memory regions that tried to be LRU-sorted. */ static unsigned long bytes_lru_sort_tried_hot_regions __read_mostly; module_param(bytes_lru_sort_tried_hot_regions, ulong, 0400); /* * Number of hot memory regions that successfully be LRU-sorted. */ static unsigned long nr_lru_sorted_hot_regions __read_mostly; module_param(nr_lru_sorted_hot_regions, ulong, 0400); /* * Total bytes of hot memory regions that successfully be LRU-sorted. */ static unsigned long bytes_lru_sorted_hot_regions __read_mostly; module_param(bytes_lru_sorted_hot_regions, ulong, 0400); /* * Number of times that the time quota limit for hot regions have exceeded */ static unsigned long nr_hot_quota_exceeds __read_mostly; module_param(nr_hot_quota_exceeds, ulong, 0400); /* * Number of cold memory regions that tried to be LRU-sorted. */ static unsigned long nr_lru_sort_tried_cold_regions __read_mostly; module_param(nr_lru_sort_tried_cold_regions, ulong, 0400); /* * Total bytes of cold memory regions that tried to be LRU-sorted. */ static unsigned long bytes_lru_sort_tried_cold_regions __read_mostly; module_param(bytes_lru_sort_tried_cold_regions, ulong, 0400); /* * Number of cold memory regions that successfully be LRU-sorted. */ static unsigned long nr_lru_sorted_cold_regions __read_mostly; module_param(nr_lru_sorted_cold_regions, ulong, 0400); /* * Total bytes of cold memory regions that successfully be LRU-sorted. */ static unsigned long bytes_lru_sorted_cold_regions __read_mostly; module_param(bytes_lru_sorted_cold_regions, ulong, 0400); /* * Number of times that the time quota limit for cold regions have exceeded */ static unsigned long nr_cold_quota_exceeds __read_mostly; module_param(nr_cold_quota_exceeds, ulong, 0400); static struct damon_ctx *ctx; static struct damon_target *target; struct damon_lru_sort_ram_walk_arg { unsigned long start; unsigned long end; }; static int walk_system_ram(struct resource *res, void *arg) { struct damon_lru_sort_ram_walk_arg *a = arg; if (a->end - a->start < resource_size(res)) { a->start = res->start; a->end = res->end; } return 0; } /* * Find biggest 'System RAM' resource and store its start and end address in * @start and @end, respectively. If no System RAM is found, returns false. */ static bool get_monitoring_region(unsigned long *start, unsigned long *end) { struct damon_lru_sort_ram_walk_arg arg = {}; walk_system_ram_res(0, ULONG_MAX, &arg, walk_system_ram); if (arg.end <= arg.start) return false; *start = arg.start; *end = arg.end; return true; } /* Create a DAMON-based operation scheme for hot memory regions */ static struct damos *damon_lru_sort_new_hot_scheme(unsigned int hot_thres) { struct damos_watermarks wmarks = { .metric = DAMOS_WMARK_FREE_MEM_RATE, .interval = wmarks_interval, .high = wmarks_high, .mid = wmarks_mid, .low = wmarks_low, }; struct damos_quota quota = { /* * Do not try LRU-lists sorting of hot pages for more than half * of quota_ms milliseconds within quota_reset_interval_ms. */ .ms = quota_ms / 2, .sz = 0, .reset_interval = quota_reset_interval_ms, /* Within the quota, mark hotter regions accessed first. */ .weight_sz = 0, .weight_nr_accesses = 1, .weight_age = 0, }; struct damos *scheme = damon_new_scheme( /* Find regions having PAGE_SIZE or larger size */ PAGE_SIZE, ULONG_MAX, /* and accessed for more than the threshold */ hot_thres, UINT_MAX, /* no matter its age */ 0, UINT_MAX, /* prioritize those on LRU lists, as soon as found */ DAMOS_LRU_PRIO, /* under the quota. */ "a, /* (De)activate this according to the watermarks. */ &wmarks); return scheme; } /* Create a DAMON-based operation scheme for cold memory regions */ static struct damos *damon_lru_sort_new_cold_scheme(unsigned int cold_thres) { struct damos_watermarks wmarks = { .metric = DAMOS_WMARK_FREE_MEM_RATE, .interval = wmarks_interval, .high = wmarks_high, .mid = wmarks_mid, .low = wmarks_low, }; struct damos_quota quota = { /* * Do not try LRU-lists sorting of cold pages for more than * half of quota_ms milliseconds within * quota_reset_interval_ms. */ .ms = quota_ms / 2, .sz = 0, .reset_interval = quota_reset_interval_ms, /* Within the quota, mark colder regions not accessed first. */ .weight_sz = 0, .weight_nr_accesses = 0, .weight_age = 1, }; struct damos *scheme = damon_new_scheme( /* Find regions having PAGE_SIZE or larger size */ PAGE_SIZE, ULONG_MAX, /* and not accessed at all */ 0, 0, /* for cold_thres or more micro-seconds, and */ cold_thres, UINT_MAX, /* mark those as not accessed, as soon as found */ DAMOS_LRU_DEPRIO, /* under the quota. */ "a, /* (De)activate this according to the watermarks. */ &wmarks); return scheme; } static int damon_lru_sort_apply_parameters(void) { struct damos *scheme, *next_scheme; struct damon_addr_range addr_range; unsigned int hot_thres, cold_thres; int err = 0; err = damon_set_attrs(ctx, sample_interval, aggr_interval, 0, min_nr_regions, max_nr_regions); if (err) return err; /* free previously set schemes */ damon_for_each_scheme_safe(scheme, next_scheme, ctx) damon_destroy_scheme(scheme); /* aggr_interval / sample_interval is the maximum nr_accesses */ hot_thres = aggr_interval / sample_interval * hot_thres_access_freq / 1000; scheme = damon_lru_sort_new_hot_scheme(hot_thres); if (!scheme) return -ENOMEM; damon_add_scheme(ctx, scheme); cold_thres = cold_min_age / aggr_interval; scheme = damon_lru_sort_new_cold_scheme(cold_thres); if (!scheme) return -ENOMEM; damon_add_scheme(ctx, scheme); if (monitor_region_start > monitor_region_end) return -EINVAL; if (!monitor_region_start && !monitor_region_end && !get_monitoring_region(&monitor_region_start, &monitor_region_end)) return -EINVAL; addr_range.start = monitor_region_start; addr_range.end = monitor_region_end; return damon_set_regions(target, &addr_range, 1); } static int damon_lru_sort_turn(bool on) { int err; if (!on) { err = damon_stop(&ctx, 1); if (!err) kdamond_pid = -1; return err; } err = damon_lru_sort_apply_parameters(); if (err) return err; err = damon_start(&ctx, 1, true); if (err) return err; kdamond_pid = ctx->kdamond->pid; return 0; } static struct delayed_work damon_lru_sort_timer; static void damon_lru_sort_timer_fn(struct work_struct *work) { static bool last_enabled; bool now_enabled; now_enabled = enabled; if (last_enabled != now_enabled) { if (!damon_lru_sort_turn(now_enabled)) last_enabled = now_enabled; else enabled = last_enabled; } } static DECLARE_DELAYED_WORK(damon_lru_sort_timer, damon_lru_sort_timer_fn); static bool damon_lru_sort_initialized; static int damon_lru_sort_enabled_store(const char *val, const struct kernel_param *kp) { int rc = param_set_bool(val, kp); if (rc < 0) return rc; if (!damon_lru_sort_initialized) return rc; schedule_delayed_work(&damon_lru_sort_timer, 0); return 0; } static const struct kernel_param_ops enabled_param_ops = { .set = damon_lru_sort_enabled_store, .get = param_get_bool, }; module_param_cb(enabled, &enabled_param_ops, &enabled, 0600); MODULE_PARM_DESC(enabled, "Enable or disable DAMON_LRU_SORT (default: disabled)"); static int damon_lru_sort_handle_commit_inputs(void) { int err; if (!commit_inputs) return 0; err = damon_lru_sort_apply_parameters(); commit_inputs = false; return err; } static int damon_lru_sort_after_aggregation(struct damon_ctx *c) { struct damos *s; /* update the stats parameter */ damon_for_each_scheme(s, c) { if (s->action == DAMOS_LRU_PRIO) { nr_lru_sort_tried_hot_regions = s->stat.nr_tried; bytes_lru_sort_tried_hot_regions = s->stat.sz_tried; nr_lru_sorted_hot_regions = s->stat.nr_applied; bytes_lru_sorted_hot_regions = s->stat.sz_applied; nr_hot_quota_exceeds = s->stat.qt_exceeds; } else if (s->action == DAMOS_LRU_DEPRIO) { nr_lru_sort_tried_cold_regions = s->stat.nr_tried; bytes_lru_sort_tried_cold_regions = s->stat.sz_tried; nr_lru_sorted_cold_regions = s->stat.nr_applied; bytes_lru_sorted_cold_regions = s->stat.sz_applied; nr_cold_quota_exceeds = s->stat.qt_exceeds; } } return damon_lru_sort_handle_commit_inputs(); } static int damon_lru_sort_after_wmarks_check(struct damon_ctx *c) { return damon_lru_sort_handle_commit_inputs(); } static int __init damon_lru_sort_init(void) { ctx = damon_new_ctx(); if (!ctx) return -ENOMEM; if (damon_select_ops(ctx, DAMON_OPS_PADDR)) { damon_destroy_ctx(ctx); return -EINVAL; } ctx->callback.after_wmarks_check = damon_lru_sort_after_wmarks_check; ctx->callback.after_aggregation = damon_lru_sort_after_aggregation; target = damon_new_target(); if (!target) { damon_destroy_ctx(ctx); return -ENOMEM; } damon_add_target(ctx, target); schedule_delayed_work(&damon_lru_sort_timer, 0); damon_lru_sort_initialized = true; return 0; } module_init(damon_lru_sort_init);