| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Data Access Monitor |
| * |
| * Author: SeongJae Park <sjpark@amazon.de> |
| */ |
| |
| #define pr_fmt(fmt) "damon: " fmt |
| |
| #include <linux/damon.h> |
| #include <linux/delay.h> |
| #include <linux/kthread.h> |
| #include <linux/mm.h> |
| #include <linux/slab.h> |
| #include <linux/string.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/damon.h> |
| |
| #ifdef CONFIG_DAMON_KUNIT_TEST |
| #undef DAMON_MIN_REGION |
| #define DAMON_MIN_REGION 1 |
| #endif |
| |
| static DEFINE_MUTEX(damon_lock); |
| static int nr_running_ctxs; |
| |
| /* |
| * Construct a damon_region struct |
| * |
| * Returns the pointer to the new struct if success, or NULL otherwise |
| */ |
| struct damon_region *damon_new_region(unsigned long start, unsigned long end) |
| { |
| struct damon_region *region; |
| |
| region = kmalloc(sizeof(*region), GFP_KERNEL); |
| if (!region) |
| return NULL; |
| |
| region->ar.start = start; |
| region->ar.end = end; |
| region->nr_accesses = 0; |
| INIT_LIST_HEAD(®ion->list); |
| |
| region->age = 0; |
| region->last_nr_accesses = 0; |
| |
| return region; |
| } |
| |
| void damon_add_region(struct damon_region *r, struct damon_target *t) |
| { |
| list_add_tail(&r->list, &t->regions_list); |
| t->nr_regions++; |
| } |
| |
| static void damon_del_region(struct damon_region *r, struct damon_target *t) |
| { |
| list_del(&r->list); |
| t->nr_regions--; |
| } |
| |
| static void damon_free_region(struct damon_region *r) |
| { |
| kfree(r); |
| } |
| |
| void damon_destroy_region(struct damon_region *r, struct damon_target *t) |
| { |
| damon_del_region(r, t); |
| damon_free_region(r); |
| } |
| |
| struct damos *damon_new_scheme( |
| unsigned long min_sz_region, unsigned long max_sz_region, |
| unsigned int min_nr_accesses, unsigned int max_nr_accesses, |
| unsigned int min_age_region, unsigned int max_age_region, |
| enum damos_action action, struct damos_quota *quota, |
| struct damos_watermarks *wmarks) |
| { |
| struct damos *scheme; |
| |
| scheme = kmalloc(sizeof(*scheme), GFP_KERNEL); |
| if (!scheme) |
| return NULL; |
| scheme->min_sz_region = min_sz_region; |
| scheme->max_sz_region = max_sz_region; |
| scheme->min_nr_accesses = min_nr_accesses; |
| scheme->max_nr_accesses = max_nr_accesses; |
| scheme->min_age_region = min_age_region; |
| scheme->max_age_region = max_age_region; |
| scheme->action = action; |
| scheme->stat = (struct damos_stat){}; |
| INIT_LIST_HEAD(&scheme->list); |
| |
| scheme->quota.ms = quota->ms; |
| scheme->quota.sz = quota->sz; |
| scheme->quota.reset_interval = quota->reset_interval; |
| scheme->quota.weight_sz = quota->weight_sz; |
| scheme->quota.weight_nr_accesses = quota->weight_nr_accesses; |
| scheme->quota.weight_age = quota->weight_age; |
| scheme->quota.total_charged_sz = 0; |
| scheme->quota.total_charged_ns = 0; |
| scheme->quota.esz = 0; |
| scheme->quota.charged_sz = 0; |
| scheme->quota.charged_from = 0; |
| scheme->quota.charge_target_from = NULL; |
| scheme->quota.charge_addr_from = 0; |
| |
| scheme->wmarks.metric = wmarks->metric; |
| scheme->wmarks.interval = wmarks->interval; |
| scheme->wmarks.high = wmarks->high; |
| scheme->wmarks.mid = wmarks->mid; |
| scheme->wmarks.low = wmarks->low; |
| scheme->wmarks.activated = true; |
| |
| return scheme; |
| } |
| |
| void damon_add_scheme(struct damon_ctx *ctx, struct damos *s) |
| { |
| list_add_tail(&s->list, &ctx->schemes); |
| } |
| |
| static void damon_del_scheme(struct damos *s) |
| { |
| list_del(&s->list); |
| } |
| |
| static void damon_free_scheme(struct damos *s) |
| { |
| kfree(s); |
| } |
| |
| void damon_destroy_scheme(struct damos *s) |
| { |
| damon_del_scheme(s); |
| damon_free_scheme(s); |
| } |
| |
| /* |
| * Construct a damon_target struct |
| * |
| * Returns the pointer to the new struct if success, or NULL otherwise |
| */ |
| struct damon_target *damon_new_target(unsigned long id) |
| { |
| struct damon_target *t; |
| |
| t = kmalloc(sizeof(*t), GFP_KERNEL); |
| if (!t) |
| return NULL; |
| |
| t->id = id; |
| t->nr_regions = 0; |
| INIT_LIST_HEAD(&t->regions_list); |
| INIT_LIST_HEAD(&t->list); |
| |
| return t; |
| } |
| |
| void damon_add_target(struct damon_ctx *ctx, struct damon_target *t) |
| { |
| list_add_tail(&t->list, &ctx->adaptive_targets); |
| } |
| |
| bool damon_targets_empty(struct damon_ctx *ctx) |
| { |
| return list_empty(&ctx->adaptive_targets); |
| } |
| |
| static void damon_del_target(struct damon_target *t) |
| { |
| list_del(&t->list); |
| } |
| |
| void damon_free_target(struct damon_target *t) |
| { |
| struct damon_region *r, *next; |
| |
| damon_for_each_region_safe(r, next, t) |
| damon_free_region(r); |
| kfree(t); |
| } |
| |
| void damon_destroy_target(struct damon_target *t) |
| { |
| damon_del_target(t); |
| damon_free_target(t); |
| } |
| |
| unsigned int damon_nr_regions(struct damon_target *t) |
| { |
| return t->nr_regions; |
| } |
| |
| struct damon_ctx *damon_new_ctx(void) |
| { |
| struct damon_ctx *ctx; |
| |
| ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); |
| if (!ctx) |
| return NULL; |
| |
| ctx->sample_interval = 5 * 1000; |
| ctx->aggr_interval = 100 * 1000; |
| ctx->primitive_update_interval = 60 * 1000 * 1000; |
| |
| ktime_get_coarse_ts64(&ctx->last_aggregation); |
| ctx->last_primitive_update = ctx->last_aggregation; |
| |
| mutex_init(&ctx->kdamond_lock); |
| |
| ctx->min_nr_regions = 10; |
| ctx->max_nr_regions = 1000; |
| |
| INIT_LIST_HEAD(&ctx->adaptive_targets); |
| INIT_LIST_HEAD(&ctx->schemes); |
| |
| return ctx; |
| } |
| |
| static void damon_destroy_targets(struct damon_ctx *ctx) |
| { |
| struct damon_target *t, *next_t; |
| |
| if (ctx->primitive.cleanup) { |
| ctx->primitive.cleanup(ctx); |
| return; |
| } |
| |
| damon_for_each_target_safe(t, next_t, ctx) |
| damon_destroy_target(t); |
| } |
| |
| void damon_destroy_ctx(struct damon_ctx *ctx) |
| { |
| struct damos *s, *next_s; |
| |
| damon_destroy_targets(ctx); |
| |
| damon_for_each_scheme_safe(s, next_s, ctx) |
| damon_destroy_scheme(s); |
| |
| kfree(ctx); |
| } |
| |
| /** |
| * damon_set_targets() - Set monitoring targets. |
| * @ctx: monitoring context |
| * @ids: array of target ids |
| * @nr_ids: number of entries in @ids |
| * |
| * This function should not be called while the kdamond is running. |
| * |
| * Return: 0 on success, negative error code otherwise. |
| */ |
| int damon_set_targets(struct damon_ctx *ctx, |
| unsigned long *ids, ssize_t nr_ids) |
| { |
| ssize_t i; |
| struct damon_target *t, *next; |
| |
| damon_destroy_targets(ctx); |
| |
| for (i = 0; i < nr_ids; i++) { |
| t = damon_new_target(ids[i]); |
| if (!t) { |
| /* The caller should do cleanup of the ids itself */ |
| damon_for_each_target_safe(t, next, ctx) |
| damon_destroy_target(t); |
| return -ENOMEM; |
| } |
| damon_add_target(ctx, t); |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * damon_set_attrs() - Set attributes for the monitoring. |
| * @ctx: monitoring context |
| * @sample_int: time interval between samplings |
| * @aggr_int: time interval between aggregations |
| * @primitive_upd_int: time interval between monitoring primitive updates |
| * @min_nr_reg: minimal number of regions |
| * @max_nr_reg: maximum number of regions |
| * |
| * This function should not be called while the kdamond is running. |
| * Every time interval is in micro-seconds. |
| * |
| * Return: 0 on success, negative error code otherwise. |
| */ |
| int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int, |
| unsigned long aggr_int, unsigned long primitive_upd_int, |
| unsigned long min_nr_reg, unsigned long max_nr_reg) |
| { |
| if (min_nr_reg < 3) |
| return -EINVAL; |
| if (min_nr_reg > max_nr_reg) |
| return -EINVAL; |
| |
| ctx->sample_interval = sample_int; |
| ctx->aggr_interval = aggr_int; |
| ctx->primitive_update_interval = primitive_upd_int; |
| ctx->min_nr_regions = min_nr_reg; |
| ctx->max_nr_regions = max_nr_reg; |
| |
| return 0; |
| } |
| |
| /** |
| * damon_set_schemes() - Set data access monitoring based operation schemes. |
| * @ctx: monitoring context |
| * @schemes: array of the schemes |
| * @nr_schemes: number of entries in @schemes |
| * |
| * This function should not be called while the kdamond of the context is |
| * running. |
| * |
| * Return: 0 if success, or negative error code otherwise. |
| */ |
| int damon_set_schemes(struct damon_ctx *ctx, struct damos **schemes, |
| ssize_t nr_schemes) |
| { |
| struct damos *s, *next; |
| ssize_t i; |
| |
| damon_for_each_scheme_safe(s, next, ctx) |
| damon_destroy_scheme(s); |
| for (i = 0; i < nr_schemes; i++) |
| damon_add_scheme(ctx, schemes[i]); |
| return 0; |
| } |
| |
| /** |
| * damon_nr_running_ctxs() - Return number of currently running contexts. |
| */ |
| int damon_nr_running_ctxs(void) |
| { |
| int nr_ctxs; |
| |
| mutex_lock(&damon_lock); |
| nr_ctxs = nr_running_ctxs; |
| mutex_unlock(&damon_lock); |
| |
| return nr_ctxs; |
| } |
| |
| /* Returns the size upper limit for each monitoring region */ |
| static unsigned long damon_region_sz_limit(struct damon_ctx *ctx) |
| { |
| struct damon_target *t; |
| struct damon_region *r; |
| unsigned long sz = 0; |
| |
| damon_for_each_target(t, ctx) { |
| damon_for_each_region(r, t) |
| sz += r->ar.end - r->ar.start; |
| } |
| |
| if (ctx->min_nr_regions) |
| sz /= ctx->min_nr_regions; |
| if (sz < DAMON_MIN_REGION) |
| sz = DAMON_MIN_REGION; |
| |
| return sz; |
| } |
| |
| static int kdamond_fn(void *data); |
| |
| /* |
| * __damon_start() - Starts monitoring with given context. |
| * @ctx: monitoring context |
| * |
| * This function should be called while damon_lock is hold. |
| * |
| * Return: 0 on success, negative error code otherwise. |
| */ |
| static int __damon_start(struct damon_ctx *ctx) |
| { |
| int err = -EBUSY; |
| |
| mutex_lock(&ctx->kdamond_lock); |
| if (!ctx->kdamond) { |
| err = 0; |
| ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond.%d", |
| nr_running_ctxs); |
| if (IS_ERR(ctx->kdamond)) { |
| err = PTR_ERR(ctx->kdamond); |
| ctx->kdamond = NULL; |
| } |
| } |
| mutex_unlock(&ctx->kdamond_lock); |
| |
| return err; |
| } |
| |
| /** |
| * damon_start() - Starts the monitorings for a given group of contexts. |
| * @ctxs: an array of the pointers for contexts to start monitoring |
| * @nr_ctxs: size of @ctxs |
| * |
| * This function starts a group of monitoring threads for a group of monitoring |
| * contexts. One thread per each context is created and run in parallel. The |
| * caller should handle synchronization between the threads by itself. If a |
| * group of threads that created by other 'damon_start()' call is currently |
| * running, this function does nothing but returns -EBUSY. |
| * |
| * Return: 0 on success, negative error code otherwise. |
| */ |
| int damon_start(struct damon_ctx **ctxs, int nr_ctxs) |
| { |
| int i; |
| int err = 0; |
| |
| mutex_lock(&damon_lock); |
| if (nr_running_ctxs) { |
| mutex_unlock(&damon_lock); |
| return -EBUSY; |
| } |
| |
| for (i = 0; i < nr_ctxs; i++) { |
| err = __damon_start(ctxs[i]); |
| if (err) |
| break; |
| nr_running_ctxs++; |
| } |
| mutex_unlock(&damon_lock); |
| |
| return err; |
| } |
| |
| /* |
| * __damon_stop() - Stops monitoring of given context. |
| * @ctx: monitoring context |
| * |
| * Return: 0 on success, negative error code otherwise. |
| */ |
| static int __damon_stop(struct damon_ctx *ctx) |
| { |
| struct task_struct *tsk; |
| |
| mutex_lock(&ctx->kdamond_lock); |
| tsk = ctx->kdamond; |
| if (tsk) { |
| get_task_struct(tsk); |
| mutex_unlock(&ctx->kdamond_lock); |
| kthread_stop(tsk); |
| put_task_struct(tsk); |
| return 0; |
| } |
| mutex_unlock(&ctx->kdamond_lock); |
| |
| return -EPERM; |
| } |
| |
| /** |
| * damon_stop() - Stops the monitorings for a given group of contexts. |
| * @ctxs: an array of the pointers for contexts to stop monitoring |
| * @nr_ctxs: size of @ctxs |
| * |
| * Return: 0 on success, negative error code otherwise. |
| */ |
| int damon_stop(struct damon_ctx **ctxs, int nr_ctxs) |
| { |
| int i, err = 0; |
| |
| for (i = 0; i < nr_ctxs; i++) { |
| /* nr_running_ctxs is decremented in kdamond_fn */ |
| err = __damon_stop(ctxs[i]); |
| if (err) |
| return err; |
| } |
| |
| return err; |
| } |
| |
| /* |
| * damon_check_reset_time_interval() - Check if a time interval is elapsed. |
| * @baseline: the time to check whether the interval has elapsed since |
| * @interval: the time interval (microseconds) |
| * |
| * See whether the given time interval has passed since the given baseline |
| * time. If so, it also updates the baseline to current time for next check. |
| * |
| * Return: true if the time interval has passed, or false otherwise. |
| */ |
| static bool damon_check_reset_time_interval(struct timespec64 *baseline, |
| unsigned long interval) |
| { |
| struct timespec64 now; |
| |
| ktime_get_coarse_ts64(&now); |
| if ((timespec64_to_ns(&now) - timespec64_to_ns(baseline)) < |
| interval * 1000) |
| return false; |
| *baseline = now; |
| return true; |
| } |
| |
| /* |
| * Check whether it is time to flush the aggregated information |
| */ |
| static bool kdamond_aggregate_interval_passed(struct damon_ctx *ctx) |
| { |
| return damon_check_reset_time_interval(&ctx->last_aggregation, |
| ctx->aggr_interval); |
| } |
| |
| /* |
| * Reset the aggregated monitoring results ('nr_accesses' of each region). |
| */ |
| static void kdamond_reset_aggregated(struct damon_ctx *c) |
| { |
| struct damon_target *t; |
| unsigned int ti = 0; /* target's index */ |
| |
| damon_for_each_target(t, c) { |
| struct damon_region *r; |
| |
| damon_for_each_region(r, t) { |
| trace_damon_aggregated(t, ti, r, damon_nr_regions(t)); |
| r->last_nr_accesses = r->nr_accesses; |
| r->nr_accesses = 0; |
| } |
| ti++; |
| } |
| } |
| |
| static void damon_split_region_at(struct damon_ctx *ctx, |
| struct damon_target *t, struct damon_region *r, |
| unsigned long sz_r); |
| |
| static bool __damos_valid_target(struct damon_region *r, struct damos *s) |
| { |
| unsigned long sz; |
| |
| sz = r->ar.end - r->ar.start; |
| return s->min_sz_region <= sz && sz <= s->max_sz_region && |
| s->min_nr_accesses <= r->nr_accesses && |
| r->nr_accesses <= s->max_nr_accesses && |
| s->min_age_region <= r->age && r->age <= s->max_age_region; |
| } |
| |
| static bool damos_valid_target(struct damon_ctx *c, struct damon_target *t, |
| struct damon_region *r, struct damos *s) |
| { |
| bool ret = __damos_valid_target(r, s); |
| |
| if (!ret || !s->quota.esz || !c->primitive.get_scheme_score) |
| return ret; |
| |
| return c->primitive.get_scheme_score(c, t, r, s) >= s->quota.min_score; |
| } |
| |
| static void damon_do_apply_schemes(struct damon_ctx *c, |
| struct damon_target *t, |
| struct damon_region *r) |
| { |
| struct damos *s; |
| |
| damon_for_each_scheme(s, c) { |
| struct damos_quota *quota = &s->quota; |
| unsigned long sz = r->ar.end - r->ar.start; |
| struct timespec64 begin, end; |
| unsigned long sz_applied = 0; |
| |
| if (!s->wmarks.activated) |
| continue; |
| |
| /* Check the quota */ |
| if (quota->esz && quota->charged_sz >= quota->esz) |
| continue; |
| |
| /* Skip previously charged regions */ |
| if (quota->charge_target_from) { |
| if (t != quota->charge_target_from) |
| continue; |
| if (r == damon_last_region(t)) { |
| quota->charge_target_from = NULL; |
| quota->charge_addr_from = 0; |
| continue; |
| } |
| if (quota->charge_addr_from && |
| r->ar.end <= quota->charge_addr_from) |
| continue; |
| |
| if (quota->charge_addr_from && r->ar.start < |
| quota->charge_addr_from) { |
| sz = ALIGN_DOWN(quota->charge_addr_from - |
| r->ar.start, DAMON_MIN_REGION); |
| if (!sz) { |
| if (r->ar.end - r->ar.start <= |
| DAMON_MIN_REGION) |
| continue; |
| sz = DAMON_MIN_REGION; |
| } |
| damon_split_region_at(c, t, r, sz); |
| r = damon_next_region(r); |
| sz = r->ar.end - r->ar.start; |
| } |
| quota->charge_target_from = NULL; |
| quota->charge_addr_from = 0; |
| } |
| |
| if (!damos_valid_target(c, t, r, s)) |
| continue; |
| |
| /* Apply the scheme */ |
| if (c->primitive.apply_scheme) { |
| if (quota->esz && |
| quota->charged_sz + sz > quota->esz) { |
| sz = ALIGN_DOWN(quota->esz - quota->charged_sz, |
| DAMON_MIN_REGION); |
| if (!sz) |
| goto update_stat; |
| damon_split_region_at(c, t, r, sz); |
| } |
| ktime_get_coarse_ts64(&begin); |
| sz_applied = c->primitive.apply_scheme(c, t, r, s); |
| ktime_get_coarse_ts64(&end); |
| quota->total_charged_ns += timespec64_to_ns(&end) - |
| timespec64_to_ns(&begin); |
| quota->charged_sz += sz; |
| if (quota->esz && quota->charged_sz >= quota->esz) { |
| quota->charge_target_from = t; |
| quota->charge_addr_from = r->ar.end + 1; |
| } |
| } |
| if (s->action != DAMOS_STAT) |
| r->age = 0; |
| |
| update_stat: |
| s->stat.nr_tried++; |
| s->stat.sz_tried += sz; |
| if (sz_applied) |
| s->stat.nr_applied++; |
| s->stat.sz_applied += sz_applied; |
| } |
| } |
| |
| /* Shouldn't be called if quota->ms and quota->sz are zero */ |
| static void damos_set_effective_quota(struct damos_quota *quota) |
| { |
| unsigned long throughput; |
| unsigned long esz; |
| |
| if (!quota->ms) { |
| quota->esz = quota->sz; |
| return; |
| } |
| |
| if (quota->total_charged_ns) |
| throughput = quota->total_charged_sz * 1000000 / |
| quota->total_charged_ns; |
| else |
| throughput = PAGE_SIZE * 1024; |
| esz = throughput * quota->ms; |
| |
| if (quota->sz && quota->sz < esz) |
| esz = quota->sz; |
| quota->esz = esz; |
| } |
| |
| static void kdamond_apply_schemes(struct damon_ctx *c) |
| { |
| struct damon_target *t; |
| struct damon_region *r, *next_r; |
| struct damos *s; |
| |
| damon_for_each_scheme(s, c) { |
| struct damos_quota *quota = &s->quota; |
| unsigned long cumulated_sz; |
| unsigned int score, max_score = 0; |
| |
| if (!s->wmarks.activated) |
| continue; |
| |
| if (!quota->ms && !quota->sz) |
| continue; |
| |
| /* New charge window starts */ |
| if (time_after_eq(jiffies, quota->charged_from + |
| msecs_to_jiffies( |
| quota->reset_interval))) { |
| if (quota->esz && quota->charged_sz >= quota->esz) |
| s->stat.qt_exceeds++; |
| quota->total_charged_sz += quota->charged_sz; |
| quota->charged_from = jiffies; |
| quota->charged_sz = 0; |
| damos_set_effective_quota(quota); |
| } |
| |
| if (!c->primitive.get_scheme_score) |
| continue; |
| |
| /* Fill up the score histogram */ |
| memset(quota->histogram, 0, sizeof(quota->histogram)); |
| damon_for_each_target(t, c) { |
| damon_for_each_region(r, t) { |
| if (!__damos_valid_target(r, s)) |
| continue; |
| score = c->primitive.get_scheme_score( |
| c, t, r, s); |
| quota->histogram[score] += |
| r->ar.end - r->ar.start; |
| if (score > max_score) |
| max_score = score; |
| } |
| } |
| |
| /* Set the min score limit */ |
| for (cumulated_sz = 0, score = max_score; ; score--) { |
| cumulated_sz += quota->histogram[score]; |
| if (cumulated_sz >= quota->esz || !score) |
| break; |
| } |
| quota->min_score = score; |
| } |
| |
| damon_for_each_target(t, c) { |
| damon_for_each_region_safe(r, next_r, t) |
| damon_do_apply_schemes(c, t, r); |
| } |
| } |
| |
| static inline unsigned long sz_damon_region(struct damon_region *r) |
| { |
| return r->ar.end - r->ar.start; |
| } |
| |
| /* |
| * Merge two adjacent regions into one region |
| */ |
| static void damon_merge_two_regions(struct damon_target *t, |
| struct damon_region *l, struct damon_region *r) |
| { |
| unsigned long sz_l = sz_damon_region(l), sz_r = sz_damon_region(r); |
| |
| l->nr_accesses = (l->nr_accesses * sz_l + r->nr_accesses * sz_r) / |
| (sz_l + sz_r); |
| l->age = (l->age * sz_l + r->age * sz_r) / (sz_l + sz_r); |
| l->ar.end = r->ar.end; |
| damon_destroy_region(r, t); |
| } |
| |
| /* |
| * Merge adjacent regions having similar access frequencies |
| * |
| * t target affected by this merge operation |
| * thres '->nr_accesses' diff threshold for the merge |
| * sz_limit size upper limit of each region |
| */ |
| static void damon_merge_regions_of(struct damon_target *t, unsigned int thres, |
| unsigned long sz_limit) |
| { |
| struct damon_region *r, *prev = NULL, *next; |
| |
| damon_for_each_region_safe(r, next, t) { |
| if (abs(r->nr_accesses - r->last_nr_accesses) > thres) |
| r->age = 0; |
| else |
| r->age++; |
| |
| if (prev && prev->ar.end == r->ar.start && |
| abs(prev->nr_accesses - r->nr_accesses) <= thres && |
| sz_damon_region(prev) + sz_damon_region(r) <= sz_limit) |
| damon_merge_two_regions(t, prev, r); |
| else |
| prev = r; |
| } |
| } |
| |
| /* |
| * Merge adjacent regions having similar access frequencies |
| * |
| * threshold '->nr_accesses' diff threshold for the merge |
| * sz_limit size upper limit of each region |
| * |
| * This function merges monitoring target regions which are adjacent and their |
| * access frequencies are similar. This is for minimizing the monitoring |
| * overhead under the dynamically changeable access pattern. If a merge was |
| * unnecessarily made, later 'kdamond_split_regions()' will revert it. |
| */ |
| static void kdamond_merge_regions(struct damon_ctx *c, unsigned int threshold, |
| unsigned long sz_limit) |
| { |
| struct damon_target *t; |
| |
| damon_for_each_target(t, c) |
| damon_merge_regions_of(t, threshold, sz_limit); |
| } |
| |
| /* |
| * Split a region in two |
| * |
| * r the region to be split |
| * sz_r size of the first sub-region that will be made |
| */ |
| static void damon_split_region_at(struct damon_ctx *ctx, |
| struct damon_target *t, struct damon_region *r, |
| unsigned long sz_r) |
| { |
| struct damon_region *new; |
| |
| new = damon_new_region(r->ar.start + sz_r, r->ar.end); |
| if (!new) |
| return; |
| |
| r->ar.end = new->ar.start; |
| |
| new->age = r->age; |
| new->last_nr_accesses = r->last_nr_accesses; |
| |
| damon_insert_region(new, r, damon_next_region(r), t); |
| } |
| |
| /* Split every region in the given target into 'nr_subs' regions */ |
| static void damon_split_regions_of(struct damon_ctx *ctx, |
| struct damon_target *t, int nr_subs) |
| { |
| struct damon_region *r, *next; |
| unsigned long sz_region, sz_sub = 0; |
| int i; |
| |
| damon_for_each_region_safe(r, next, t) { |
| sz_region = r->ar.end - r->ar.start; |
| |
| for (i = 0; i < nr_subs - 1 && |
| sz_region > 2 * DAMON_MIN_REGION; i++) { |
| /* |
| * Randomly select size of left sub-region to be at |
| * least 10 percent and at most 90% of original region |
| */ |
| sz_sub = ALIGN_DOWN(damon_rand(1, 10) * |
| sz_region / 10, DAMON_MIN_REGION); |
| /* Do not allow blank region */ |
| if (sz_sub == 0 || sz_sub >= sz_region) |
| continue; |
| |
| damon_split_region_at(ctx, t, r, sz_sub); |
| sz_region = sz_sub; |
| } |
| } |
| } |
| |
| /* |
| * Split every target region into randomly-sized small regions |
| * |
| * This function splits every target region into random-sized small regions if |
| * current total number of the regions is equal or smaller than half of the |
| * user-specified maximum number of regions. This is for maximizing the |
| * monitoring accuracy under the dynamically changeable access patterns. If a |
| * split was unnecessarily made, later 'kdamond_merge_regions()' will revert |
| * it. |
| */ |
| static void kdamond_split_regions(struct damon_ctx *ctx) |
| { |
| struct damon_target *t; |
| unsigned int nr_regions = 0; |
| static unsigned int last_nr_regions; |
| int nr_subregions = 2; |
| |
| damon_for_each_target(t, ctx) |
| nr_regions += damon_nr_regions(t); |
| |
| if (nr_regions > ctx->max_nr_regions / 2) |
| return; |
| |
| /* Maybe the middle of the region has different access frequency */ |
| if (last_nr_regions == nr_regions && |
| nr_regions < ctx->max_nr_regions / 3) |
| nr_subregions = 3; |
| |
| damon_for_each_target(t, ctx) |
| damon_split_regions_of(ctx, t, nr_subregions); |
| |
| last_nr_regions = nr_regions; |
| } |
| |
| /* |
| * Check whether it is time to check and apply the target monitoring regions |
| * |
| * Returns true if it is. |
| */ |
| static bool kdamond_need_update_primitive(struct damon_ctx *ctx) |
| { |
| return damon_check_reset_time_interval(&ctx->last_primitive_update, |
| ctx->primitive_update_interval); |
| } |
| |
| /* |
| * Check whether current monitoring should be stopped |
| * |
| * The monitoring is stopped when either the user requested to stop, or all |
| * monitoring targets are invalid. |
| * |
| * Returns true if need to stop current monitoring. |
| */ |
| static bool kdamond_need_stop(struct damon_ctx *ctx) |
| { |
| struct damon_target *t; |
| |
| if (kthread_should_stop()) |
| return true; |
| |
| if (!ctx->primitive.target_valid) |
| return false; |
| |
| damon_for_each_target(t, ctx) { |
| if (ctx->primitive.target_valid(t)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| static unsigned long damos_wmark_metric_value(enum damos_wmark_metric metric) |
| { |
| struct sysinfo i; |
| |
| switch (metric) { |
| case DAMOS_WMARK_FREE_MEM_RATE: |
| si_meminfo(&i); |
| return i.freeram * 1000 / i.totalram; |
| default: |
| break; |
| } |
| return -EINVAL; |
| } |
| |
| /* |
| * Returns zero if the scheme is active. Else, returns time to wait for next |
| * watermark check in micro-seconds. |
| */ |
| static unsigned long damos_wmark_wait_us(struct damos *scheme) |
| { |
| unsigned long metric; |
| |
| if (scheme->wmarks.metric == DAMOS_WMARK_NONE) |
| return 0; |
| |
| metric = damos_wmark_metric_value(scheme->wmarks.metric); |
| /* higher than high watermark or lower than low watermark */ |
| if (metric > scheme->wmarks.high || scheme->wmarks.low > metric) { |
| if (scheme->wmarks.activated) |
| pr_debug("deactivate a scheme (%d) for %s wmark\n", |
| scheme->action, |
| metric > scheme->wmarks.high ? |
| "high" : "low"); |
| scheme->wmarks.activated = false; |
| return scheme->wmarks.interval; |
| } |
| |
| /* inactive and higher than middle watermark */ |
| if ((scheme->wmarks.high >= metric && metric >= scheme->wmarks.mid) && |
| !scheme->wmarks.activated) |
| return scheme->wmarks.interval; |
| |
| if (!scheme->wmarks.activated) |
| pr_debug("activate a scheme (%d)\n", scheme->action); |
| scheme->wmarks.activated = true; |
| return 0; |
| } |
| |
| static void kdamond_usleep(unsigned long usecs) |
| { |
| /* See Documentation/timers/timers-howto.rst for the thresholds */ |
| if (usecs > 20 * USEC_PER_MSEC) |
| schedule_timeout_idle(usecs_to_jiffies(usecs)); |
| else |
| usleep_idle_range(usecs, usecs + 1); |
| } |
| |
| /* Returns negative error code if it's not activated but should return */ |
| static int kdamond_wait_activation(struct damon_ctx *ctx) |
| { |
| struct damos *s; |
| unsigned long wait_time; |
| unsigned long min_wait_time = 0; |
| |
| while (!kdamond_need_stop(ctx)) { |
| damon_for_each_scheme(s, ctx) { |
| wait_time = damos_wmark_wait_us(s); |
| if (!min_wait_time || wait_time < min_wait_time) |
| min_wait_time = wait_time; |
| } |
| if (!min_wait_time) |
| return 0; |
| |
| kdamond_usleep(min_wait_time); |
| } |
| return -EBUSY; |
| } |
| |
| /* |
| * The monitoring daemon that runs as a kernel thread |
| */ |
| static int kdamond_fn(void *data) |
| { |
| struct damon_ctx *ctx = (struct damon_ctx *)data; |
| struct damon_target *t; |
| struct damon_region *r, *next; |
| unsigned int max_nr_accesses = 0; |
| unsigned long sz_limit = 0; |
| bool done = false; |
| |
| pr_debug("kdamond (%d) starts\n", current->pid); |
| |
| if (ctx->primitive.init) |
| ctx->primitive.init(ctx); |
| if (ctx->callback.before_start && ctx->callback.before_start(ctx)) |
| done = true; |
| |
| sz_limit = damon_region_sz_limit(ctx); |
| |
| while (!kdamond_need_stop(ctx) && !done) { |
| if (kdamond_wait_activation(ctx)) |
| continue; |
| |
| if (ctx->primitive.prepare_access_checks) |
| ctx->primitive.prepare_access_checks(ctx); |
| if (ctx->callback.after_sampling && |
| ctx->callback.after_sampling(ctx)) |
| done = true; |
| |
| kdamond_usleep(ctx->sample_interval); |
| |
| if (ctx->primitive.check_accesses) |
| max_nr_accesses = ctx->primitive.check_accesses(ctx); |
| |
| if (kdamond_aggregate_interval_passed(ctx)) { |
| kdamond_merge_regions(ctx, |
| max_nr_accesses / 10, |
| sz_limit); |
| if (ctx->callback.after_aggregation && |
| ctx->callback.after_aggregation(ctx)) |
| done = true; |
| kdamond_apply_schemes(ctx); |
| kdamond_reset_aggregated(ctx); |
| kdamond_split_regions(ctx); |
| if (ctx->primitive.reset_aggregated) |
| ctx->primitive.reset_aggregated(ctx); |
| } |
| |
| if (kdamond_need_update_primitive(ctx)) { |
| if (ctx->primitive.update) |
| ctx->primitive.update(ctx); |
| sz_limit = damon_region_sz_limit(ctx); |
| } |
| } |
| damon_for_each_target(t, ctx) { |
| damon_for_each_region_safe(r, next, t) |
| damon_destroy_region(r, t); |
| } |
| |
| if (ctx->callback.before_terminate) |
| ctx->callback.before_terminate(ctx); |
| if (ctx->primitive.cleanup) |
| ctx->primitive.cleanup(ctx); |
| |
| pr_debug("kdamond (%d) finishes\n", current->pid); |
| mutex_lock(&ctx->kdamond_lock); |
| ctx->kdamond = NULL; |
| mutex_unlock(&ctx->kdamond_lock); |
| |
| mutex_lock(&damon_lock); |
| nr_running_ctxs--; |
| mutex_unlock(&damon_lock); |
| |
| return 0; |
| } |
| |
| #include "core-test.h" |