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authorSeongJae Park <sj@kernel.org>2023-09-16 05:09:40 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-10-04 20:32:31 +0300
commit42f994b71404b17abcd6b170de7a6aa95ffe5d4a (patch)
tree91e7994f6d09023f298f09103648aa27e121a694 /mm/damon
parenta72217ad596ec8a957e1f73e45817c3664d99f1e (diff)
downloadlinux-42f994b71404b17abcd6b170de7a6aa95ffe5d4a.tar.xz
mm/damon/core: implement scheme-specific apply interval
DAMON-based operation schemes are applied for every aggregation interval. That was mainly because schemes were using nr_accesses, which be complete to be used for every aggregation interval. However, the schemes are now using nr_accesses_bp, which is updated for each sampling interval in a way that reasonable to be used. Therefore, there is no reason to apply schemes for each aggregation interval. The unnecessary alignment with aggregation interval was also making some use cases of DAMOS tricky. Quotas setting under long aggregation interval is one such example. Suppose the aggregation interval is ten seconds, and there is a scheme having CPU quota 100ms per 1s. The scheme will actually uses 100ms per ten seconds, since it cannobe be applied before next aggregation interval. The feature is working as intended, but the results might not that intuitive for some users. This could be fixed by updating the quota to 1s per 10s. But, in the case, the CPU usage of DAMOS could look like spikes, and would actually make a bad effect to other CPU-sensitive workloads. Implement a dedicated timing interval for each DAMON-based operation scheme, namely apply_interval. The interval will be sampling interval aligned, and each scheme will be applied for its apply_interval. The interval is set to 0 by default, and it means the scheme should use the aggregation interval instead. This avoids old users getting any behavioral difference. Link: https://lkml.kernel.org/r/20230916020945.47296-5-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/damon')
-rw-r--r--mm/damon/core.c72
-rw-r--r--mm/damon/dbgfs.c3
-rw-r--r--mm/damon/lru_sort.c2
-rw-r--r--mm/damon/reclaim.c2
-rw-r--r--mm/damon/sysfs-schemes.c2
5 files changed, 72 insertions, 9 deletions
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 79fef5145a4b..5eb649bd002f 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -313,7 +313,9 @@ static struct damos_quota *damos_quota_init_priv(struct damos_quota *quota)
}
struct damos *damon_new_scheme(struct damos_access_pattern *pattern,
- enum damos_action action, struct damos_quota *quota,
+ enum damos_action action,
+ unsigned long apply_interval_us,
+ struct damos_quota *quota,
struct damos_watermarks *wmarks)
{
struct damos *scheme;
@@ -323,6 +325,13 @@ struct damos *damon_new_scheme(struct damos_access_pattern *pattern,
return NULL;
scheme->pattern = *pattern;
scheme->action = action;
+ scheme->apply_interval_us = apply_interval_us;
+ /*
+ * next_apply_sis will be set when kdamond starts. While kdamond is
+ * running, it will also updated when it is added to the DAMON context,
+ * or damon_attrs are updated.
+ */
+ scheme->next_apply_sis = 0;
INIT_LIST_HEAD(&scheme->filters);
scheme->stat = (struct damos_stat){};
INIT_LIST_HEAD(&scheme->list);
@@ -335,9 +344,21 @@ struct damos *damon_new_scheme(struct damos_access_pattern *pattern,
return scheme;
}
+static void damos_set_next_apply_sis(struct damos *s, struct damon_ctx *ctx)
+{
+ unsigned long sample_interval = ctx->attrs.sample_interval ?
+ ctx->attrs.sample_interval : 1;
+ unsigned long apply_interval = s->apply_interval_us ?
+ s->apply_interval_us : ctx->attrs.aggr_interval;
+
+ s->next_apply_sis = ctx->passed_sample_intervals +
+ apply_interval / sample_interval;
+}
+
void damon_add_scheme(struct damon_ctx *ctx, struct damos *s)
{
list_add_tail(&s->list, &ctx->schemes);
+ damos_set_next_apply_sis(s, ctx);
}
static void damon_del_scheme(struct damos *s)
@@ -558,6 +579,7 @@ int damon_set_attrs(struct damon_ctx *ctx, struct damon_attrs *attrs)
{
unsigned long sample_interval = attrs->sample_interval ?
attrs->sample_interval : 1;
+ struct damos *s;
if (attrs->min_nr_regions < 3)
return -EINVAL;
@@ -573,6 +595,10 @@ int damon_set_attrs(struct damon_ctx *ctx, struct damon_attrs *attrs)
damon_update_monitoring_results(ctx, attrs);
ctx->attrs = *attrs;
+
+ damon_for_each_scheme(s, ctx)
+ damos_set_next_apply_sis(s, ctx);
+
return 0;
}
@@ -1094,14 +1120,29 @@ static void kdamond_apply_schemes(struct damon_ctx *c)
struct damon_target *t;
struct damon_region *r, *next_r;
struct damos *s;
+ unsigned long sample_interval = c->attrs.sample_interval ?
+ c->attrs.sample_interval : 1;
+ bool has_schemes_to_apply = false;
damon_for_each_scheme(s, c) {
+ if (c->passed_sample_intervals != s->next_apply_sis)
+ continue;
+
+ s->next_apply_sis +=
+ (s->apply_interval_us ? s->apply_interval_us :
+ c->attrs.aggr_interval) / sample_interval;
+
if (!s->wmarks.activated)
continue;
+ has_schemes_to_apply = true;
+
damos_adjust_quota(c, s);
}
+ if (!has_schemes_to_apply)
+ return;
+
damon_for_each_target(t, c) {
damon_for_each_region_safe(r, next_r, t)
damon_do_apply_schemes(c, t, r);
@@ -1372,11 +1413,19 @@ static void kdamond_init_intervals_sis(struct damon_ctx *ctx)
{
unsigned long sample_interval = ctx->attrs.sample_interval ?
ctx->attrs.sample_interval : 1;
+ unsigned long apply_interval;
+ struct damos *scheme;
ctx->passed_sample_intervals = 0;
ctx->next_aggregation_sis = ctx->attrs.aggr_interval / sample_interval;
ctx->next_ops_update_sis = ctx->attrs.ops_update_interval /
sample_interval;
+
+ damon_for_each_scheme(scheme, ctx) {
+ apply_interval = scheme->apply_interval_us ?
+ scheme->apply_interval_us : ctx->attrs.aggr_interval;
+ scheme->next_apply_sis = apply_interval / sample_interval;
+ }
}
/*
@@ -1428,19 +1477,28 @@ static int kdamond_fn(void *data)
if (ctx->ops.check_accesses)
max_nr_accesses = ctx->ops.check_accesses(ctx);
- sample_interval = ctx->attrs.sample_interval ?
- ctx->attrs.sample_interval : 1;
if (ctx->passed_sample_intervals == next_aggregation_sis) {
- ctx->next_aggregation_sis = next_aggregation_sis +
- ctx->attrs.aggr_interval / sample_interval;
kdamond_merge_regions(ctx,
max_nr_accesses / 10,
sz_limit);
if (ctx->callback.after_aggregation &&
ctx->callback.after_aggregation(ctx))
break;
- if (!list_empty(&ctx->schemes))
- kdamond_apply_schemes(ctx);
+ }
+
+ /*
+ * do kdamond_apply_schemes() after kdamond_merge_regions() if
+ * possible, to reduce overhead
+ */
+ if (!list_empty(&ctx->schemes))
+ kdamond_apply_schemes(ctx);
+
+ sample_interval = ctx->attrs.sample_interval ?
+ ctx->attrs.sample_interval : 1;
+ if (ctx->passed_sample_intervals == next_aggregation_sis) {
+ ctx->next_aggregation_sis = next_aggregation_sis +
+ ctx->attrs.aggr_interval / sample_interval;
+
kdamond_reset_aggregated(ctx);
kdamond_split_regions(ctx);
if (ctx->ops.reset_aggregated)
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 124f0f8c97b7..dc0ea1fc30ca 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -278,7 +278,8 @@ static struct damos **str_to_schemes(const char *str, ssize_t len,
goto fail;
pos += parsed;
- scheme = damon_new_scheme(&pattern, action, &quota, &wmarks);
+ scheme = damon_new_scheme(&pattern, action, 0, &quota,
+ &wmarks);
if (!scheme)
goto fail;
diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index 7b8fce2f67a8..3ecdcc029443 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -158,6 +158,8 @@ static struct damos *damon_lru_sort_new_scheme(
pattern,
/* (de)prioritize on LRU-lists */
action,
+ /* for each aggregation interval */
+ 0,
/* under the quota. */
&quota,
/* (De)activate this according to the watermarks. */
diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index 648d2a85523a..ab974e477d2f 100644
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -142,6 +142,8 @@ static struct damos *damon_reclaim_new_scheme(void)
&pattern,
/* page out those, as soon as found */
DAMOS_PAGEOUT,
+ /* for each aggregation interval */
+ 0,
/* under the quota. */
&damon_reclaim_quota,
/* (De)activate this according to the watermarks. */
diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 093700f50b18..3d30e85596b0 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1610,7 +1610,7 @@ static struct damos *damon_sysfs_mk_scheme(
.low = sysfs_wmarks->low,
};
- scheme = damon_new_scheme(&pattern, sysfs_scheme->action, &quota,
+ scheme = damon_new_scheme(&pattern, sysfs_scheme->action, 0, &quota,
&wmarks);
if (!scheme)
return NULL;