diff options
Diffstat (limited to 'mm/damon')
| -rw-r--r-- | mm/damon/core.c | 224 |
1 files changed, 215 insertions, 9 deletions
diff --git a/mm/damon/core.c b/mm/damon/core.c index 947486a150ce..28a2c78914fa 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -10,8 +10,12 @@ #include <linux/damon.h> #include <linux/delay.h> #include <linux/kthread.h> +#include <linux/random.h> #include <linux/slab.h> +/* Get a random number in [l, r) */ +#define damon_rand(l, r) (l + prandom_u32_max(r - l)) + static DEFINE_MUTEX(damon_lock); static int nr_running_ctxs; @@ -40,19 +44,23 @@ struct damon_region *damon_new_region(unsigned long start, unsigned long end) * Add a region between two other regions */ inline void damon_insert_region(struct damon_region *r, - struct damon_region *prev, struct damon_region *next) + struct damon_region *prev, struct damon_region *next, + struct damon_target *t) { __list_add(&r->list, &prev->list, &next->list); + t->nr_regions++; } 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) +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) @@ -60,9 +68,9 @@ static void damon_free_region(struct damon_region *r) kfree(r); } -void damon_destroy_region(struct damon_region *r) +void damon_destroy_region(struct damon_region *r, struct damon_target *t) { - damon_del_region(r); + damon_del_region(r, t); damon_free_region(r); } @@ -80,6 +88,7 @@ struct damon_target *damon_new_target(unsigned long id) return NULL; t->id = id; + t->nr_regions = 0; INIT_LIST_HEAD(&t->regions_list); return t; @@ -87,7 +96,7 @@ struct damon_target *damon_new_target(unsigned long id) void damon_add_target(struct damon_ctx *ctx, struct damon_target *t) { - list_add_tail(&t->list, &ctx->region_targets); + list_add_tail(&t->list, &ctx->adaptive_targets); } static void damon_del_target(struct damon_target *t) @@ -110,6 +119,11 @@ void damon_destroy_target(struct damon_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; @@ -127,7 +141,10 @@ struct damon_ctx *damon_new_ctx(void) mutex_init(&ctx->kdamond_lock); - INIT_LIST_HEAD(&ctx->region_targets); + ctx->min_nr_regions = 10; + ctx->max_nr_regions = 1000; + + INIT_LIST_HEAD(&ctx->adaptive_targets); return ctx; } @@ -157,6 +174,8 @@ void damon_destroy_ctx(struct damon_ctx *ctx) * @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. @@ -164,15 +183,49 @@ void damon_destroy_ctx(struct damon_ctx *ctx) * 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 aggr_int, unsigned long primitive_upd_int, + unsigned long min_nr_reg, unsigned long max_nr_reg) { + if (min_nr_reg < 3) { + pr_err("min_nr_regions (%lu) must be at least 3\n", + min_nr_reg); + return -EINVAL; + } + if (min_nr_reg > max_nr_reg) { + pr_err("invalid nr_regions. min (%lu) > max (%lu)\n", + 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; } +/* 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 bool damon_kdamond_running(struct damon_ctx *ctx) { bool running; @@ -339,6 +392,150 @@ static void kdamond_reset_aggregated(struct damon_ctx *c) } } +#define sz_damon_region(r) (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->ar.end = r->ar.end; + damon_destroy_region(r, t); +} + +#define diff_of(a, b) (a > b ? a - b : b - a) + +/* + * 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 (prev && prev->ar.end == r->ar.start && + diff_of(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; + + 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 * @@ -395,6 +592,8 @@ 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; mutex_lock(&ctx->kdamond_lock); pr_info("kdamond (%d) starts\n", ctx->kdamond->pid); @@ -405,6 +604,8 @@ static int kdamond_fn(void *data) if (ctx->callback.before_start && ctx->callback.before_start(ctx)) set_kdamond_stop(ctx); + sz_limit = damon_region_sz_limit(ctx); + while (!kdamond_need_stop(ctx)) { if (ctx->primitive.prepare_access_checks) ctx->primitive.prepare_access_checks(ctx); @@ -415,13 +616,17 @@ static int kdamond_fn(void *data) usleep_range(ctx->sample_interval, ctx->sample_interval + 1); if (ctx->primitive.check_accesses) - ctx->primitive.check_accesses(ctx); + 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)) set_kdamond_stop(ctx); kdamond_reset_aggregated(ctx); + kdamond_split_regions(ctx); if (ctx->primitive.reset_aggregated) ctx->primitive.reset_aggregated(ctx); } @@ -429,11 +634,12 @@ static int kdamond_fn(void *data) 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); + damon_destroy_region(r, t); } if (ctx->callback.before_terminate && |