From: SeongJae Park <sj@xxxxxxxxxx> Subject: mm/damon/schemes: implement size quota for schemes application speed control There could be arbitrarily large memory regions fulfilling the target data access pattern of a DAMON-based operation scheme. In the case, applying the action of the scheme could incur too high overhead. To provide an intuitive way for avoiding it, this commit implements a feature called size quota. If the quota is set, DAMON tries to apply the action only up to the given amount of memory regions within a given time window. Link: https://lkml.kernel.org/r/20211019150731.16699-3-sj@xxxxxxxxxx Signed-off-by: SeongJae Park <sj@xxxxxxxxxx> Cc: Amit Shah <amit@xxxxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: David Hildenbrand <david@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: David Woodhouse <dwmw@xxxxxxxxxx> Cc: Greg Thelen <gthelen@xxxxxxxxxx> Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Leonard Foerster <foersleo@xxxxxxxxx> Cc: Marco Elver <elver@xxxxxxxxxx> Cc: Markus Boehme <markubo@xxxxxxxxx> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/damon.h | 36 +++++++++++++++++++++--- mm/damon/core.c | 60 ++++++++++++++++++++++++++++++++++------ mm/damon/dbgfs.c | 4 ++ 3 files changed, 87 insertions(+), 13 deletions(-) --- a/include/linux/damon.h~mm-damon-schemes-implement-size-quota-for-schemes-application-speed-control +++ a/include/linux/damon.h @@ -90,6 +90,26 @@ enum damos_action { }; /** + * struct damos_quota - Controls the aggressiveness of the given scheme. + * @sz: Maximum bytes of memory that the action can be applied. + * @reset_interval: Charge reset interval in milliseconds. + * + * To avoid consuming too much CPU time or IO resources for applying the + * &struct damos->action to large memory, DAMON allows users to set a size + * quota. The quota can be set by writing non-zero values to &sz. If the size + * quota is set, DAMON tries to apply the action only up to &sz bytes within + * &reset_interval. + */ +struct damos_quota { + unsigned long sz; + unsigned long reset_interval; + +/* private: For charging the quota */ + unsigned long charged_sz; + unsigned long charged_from; +}; + +/** * struct damos - Represents a Data Access Monitoring-based Operation Scheme. * @min_sz_region: Minimum size of target regions. * @max_sz_region: Maximum size of target regions. @@ -98,13 +118,20 @@ enum damos_action { * @min_age_region: Minimum age of target regions. * @max_age_region: Maximum age of target regions. * @action: &damo_action to be applied to the target regions. + * @quota: Control the aggressiveness of this scheme. * @stat_count: Total number of regions that this scheme is applied. * @stat_sz: Total size of regions that this scheme is applied. * @list: List head for siblings. * - * For each aggregation interval, DAMON applies @action to monitoring target - * regions fit in the condition and updates the statistics. Note that both - * the minimums and the maximums are inclusive. + * For each aggregation interval, DAMON finds regions which fit in the + * condition (&min_sz_region, &max_sz_region, &min_nr_accesses, + * &max_nr_accesses, &min_age_region, &max_age_region) and applies &action to + * those. To avoid consuming too much CPU time or IO resources for the + * &action, "a is used. + * + * After applying the &action to each region, &stat_count and &stat_sz is + * updated to reflect the number of regions and total size of regions that the + * &action is applied. */ struct damos { unsigned long min_sz_region; @@ -114,6 +141,7 @@ struct damos { unsigned int min_age_region; unsigned int max_age_region; enum damos_action action; + struct damos_quota quota; unsigned long stat_count; unsigned long stat_sz; struct list_head list; @@ -310,7 +338,7 @@ 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); + enum damos_action action, struct damos_quota *quota); void damon_add_scheme(struct damon_ctx *ctx, struct damos *s); void damon_destroy_scheme(struct damos *s); --- a/mm/damon/core.c~mm-damon-schemes-implement-size-quota-for-schemes-application-speed-control +++ a/mm/damon/core.c @@ -89,7 +89,7 @@ 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) + enum damos_action action, struct damos_quota *quota) { struct damos *scheme; @@ -107,6 +107,11 @@ struct damos *damon_new_scheme( scheme->stat_sz = 0; INIT_LIST_HEAD(&scheme->list); + scheme->quota.sz = quota->sz; + scheme->quota.reset_interval = quota->reset_interval; + scheme->quota.charged_sz = 0; + scheme->quota.charged_from = 0; + return scheme; } @@ -530,15 +535,25 @@ static void kdamond_reset_aggregated(str } } +static void damon_split_region_at(struct damon_ctx *ctx, + struct damon_target *t, struct damon_region *r, + unsigned long sz_r); + static void damon_do_apply_schemes(struct damon_ctx *c, struct damon_target *t, struct damon_region *r) { struct damos *s; - unsigned long sz; damon_for_each_scheme(s, c) { - sz = r->ar.end - r->ar.start; + struct damos_quota *quota = &s->quota; + unsigned long sz = r->ar.end - r->ar.start; + + /* Check the quota */ + if (quota->sz && quota->charged_sz >= quota->sz) + continue; + + /* Check the target regions condition */ if (sz < s->min_sz_region || s->max_sz_region < sz) continue; if (r->nr_accesses < s->min_nr_accesses || @@ -546,22 +561,51 @@ static void damon_do_apply_schemes(struc continue; if (r->age < s->min_age_region || s->max_age_region < r->age) continue; - s->stat_count++; - s->stat_sz += sz; - if (c->primitive.apply_scheme) + + /* Apply the scheme */ + if (c->primitive.apply_scheme) { + if (quota->sz && quota->charged_sz + sz > quota->sz) { + sz = ALIGN_DOWN(quota->sz - quota->charged_sz, + DAMON_MIN_REGION); + if (!sz) + goto update_stat; + damon_split_region_at(c, t, r, sz); + } c->primitive.apply_scheme(c, t, r, s); + quota->charged_sz += sz; + } if (s->action != DAMOS_STAT) r->age = 0; + +update_stat: + s->stat_count++; + s->stat_sz += sz; } } static void kdamond_apply_schemes(struct damon_ctx *c) { struct damon_target *t; - struct damon_region *r; + struct damon_region *r, *next_r; + struct damos *s; + + damon_for_each_scheme(s, c) { + struct damos_quota *quota = &s->quota; + + if (!quota->sz) + continue; + + /* New charge window starts */ + if (time_after_eq(jiffies, quota->charged_from + + msecs_to_jiffies( + quota->reset_interval))) { + quota->charged_from = jiffies; + quota->charged_sz = 0; + } + } damon_for_each_target(t, c) { - damon_for_each_region(r, t) + damon_for_each_region_safe(r, next_r, t) damon_do_apply_schemes(c, t, r); } } --- a/mm/damon/dbgfs.c~mm-damon-schemes-implement-size-quota-for-schemes-application-speed-control +++ a/mm/damon/dbgfs.c @@ -188,6 +188,8 @@ static struct damos **str_to_schemes(con *nr_schemes = 0; while (pos < len && *nr_schemes < max_nr_schemes) { + struct damos_quota quota = {}; + ret = sscanf(&str[pos], "%lu %lu %u %u %u %u %u%n", &min_sz, &max_sz, &min_nr_a, &max_nr_a, &min_age, &max_age, &action, &parsed); @@ -200,7 +202,7 @@ static struct damos **str_to_schemes(con pos += parsed; scheme = damon_new_scheme(min_sz, max_sz, min_nr_a, max_nr_a, - min_age, max_age, action); + min_age, max_age, action, "a); if (!scheme) goto fail; _
