For deep level investigation of DAMON, knowing exactly to what regions
each DAMON-based operation scheme is applied is helpful. It can also be
very helpful for efficient monitoring results passing when the user has
interest in regions of specific access patterns. Add a new DAMON
callback that will be called before each scheme is applied to each
region, to provide the functionality to the kernel API users.
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
include/linux/damon.h | 5 +++++
mm/damon/core.c | 6 +++++-
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 620ada094c3b..35630634d790 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -357,6 +357,7 @@ struct damon_operations {
* @after_wmarks_check: Called after each schemes' watermarks check.
* @after_sampling: Called after each sampling.
* @after_aggregation: Called after each aggregation.
+ * @before_damos_apply: Called before applying DAMOS action.
* @before_terminate: Called before terminating the monitoring.
* @private: User private data.
*
@@ -385,6 +386,10 @@ struct damon_callback {
int (*after_wmarks_check)(struct damon_ctx *context);
int (*after_sampling)(struct damon_ctx *context);
int (*after_aggregation)(struct damon_ctx *context);
+ int (*before_damos_apply)(struct damon_ctx *context,
+ struct damon_target *target,
+ struct damon_region *region,
+ struct damos *scheme);
void (*before_terminate)(struct damon_ctx *context);
};
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 9ee9f752f6fc..f196feed78c7 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -765,6 +765,7 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t,
unsigned long sz = damon_sz_region(r);
struct timespec64 begin, end;
unsigned long sz_applied = 0;
+ int err = 0;
if (c->ops.apply_scheme) {
if (quota->esz && quota->charged_sz + sz > quota->esz) {
@@ -775,7 +776,10 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t,
damon_split_region_at(t, r, sz);
}
ktime_get_coarse_ts64(&begin);
- sz_applied = c->ops.apply_scheme(c, t, r, s);
+ if (c->callback.before_damos_apply)
+ err = c->callback.before_damos_apply(c, t, r, s);
+ if (!err)
+ sz_applied = c->ops.apply_scheme(c, t, r, s);
ktime_get_coarse_ts64(&end);
quota->total_charged_ns += timespec64_to_ns(&end) -
timespec64_to_ns(&begin);
--
2.25.1
