[RFC PATCH 2/3] mm/damon/core: introduce damon_probe_hits_mvsum()

[SeongJae Park <sj@kernel.org>]

Implement a function for getting a reasonable best effort quality pseudo
moving sums of probe_hits on demands.  It reuses the internal function
for the pseudo moving sum for data access frequency (nr_accesses).

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 include/linux/damon.h |  2 ++
 mm/damon/core.c       | 21 +++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index f0dd45ca788f5..46394171cd2d0 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -1005,6 +1005,8 @@ void damon_add_probe(struct damon_ctx *ctx, struct damon_probe *probe);
 struct damon_region *damon_new_region(unsigned long start, unsigned long end);
 unsigned int damon_nr_accesses_mvsum(struct damon_region *r,
 		struct damon_ctx *ctx);
+unsigned char damon_probe_hits_mvsum(int probe_idx, struct damon_region *r,
+		struct damon_ctx *ctx);
 
 int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
 		unsigned int nr_ranges, unsigned long min_region_sz);
diff --git a/mm/damon/core.c b/mm/damon/core.c
index e84f2f1b07cc6..b5f63f2f726be 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -275,6 +275,27 @@ unsigned int damon_nr_accesses_mvsum(struct damon_region *r,
 			left_window_bp);
 }
 
+unsigned char damon_probe_hits_mvsum(int probe_idx, struct damon_region *r,
+		struct damon_ctx *ctx)
+{
+	unsigned long sample_interval, aggr_interval;
+	unsigned long window_len, left_window, left_window_bp;
+
+	sample_interval = ctx->attrs.sample_interval ? : 1;
+	aggr_interval =  ctx->attrs.aggr_interval ? : 1;
+	window_len = aggr_interval / sample_interval;
+	if (time_after_eq(ctx->passed_sample_intervals,
+				ctx->next_aggregation_sis))
+		left_window = 0;
+	else
+		left_window = ctx->next_aggregation_sis -
+			ctx->passed_sample_intervals;
+	left_window_bp = mult_frac(left_window, 10000, window_len);
+
+	return damon_mvsum(r->probe_hits[probe_idx],
+			r->last_probe_hits[probe_idx], left_window_bp);
+}
+
 #ifdef CONFIG_DAMON_DEBUG_SANITY
 static void damon_verify_new_region(unsigned long start, unsigned long end)
 {
-- 
2.47.3