+ mm-damon-core-add-trace-point-for-damos-stat-per-apply-interval.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/damon/core: add trace point for damos stat per apply interval
has been added to the -mm mm-new branch.  Its filename is
     mm-damon-core-add-trace-point-for-damos-stat-per-apply-interval.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-core-add-trace-point-for-damos-stat-per-apply-interval.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
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fixup patches in mm-new.

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------------------------------------------------------
From: SeongJae Park <sj@kernel.org>
Subject: mm/damon/core: add trace point for damos stat per apply interval
Date: Tue, 16 Dec 2025 00:01:25 -0800

DAMON users can read DAMOS stats via DAMON sysfs interface.  It enables
efficient, simple and flexible usages of the stats.  Especially for
systems not having advanced tools like perf or bpftrace, that can be
useful.  But if the advanced tools are available, exposing the stats via
tracepoint can reduce unnecessary reimplementation of the wheels.  Add a
new tracepoint for DAMOS stats, namely damos_stat_after_apply_interval. 
The tracepoint is triggered for each scheme's apply interval and exposes
the whole stat values.  If the user needs sub-apply interval information
for any chance, damos_before_apply tracepoint could be used.

Link: https://lkml.kernel.org/r/20251216080128.42991-13-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/trace/events/damon.h |   41 +++++++++++++++++++++++++++++++++
 mm/damon/core.c              |   17 +++++++++++++
 2 files changed, 58 insertions(+)

--- a/include/trace/events/damon.h~mm-damon-core-add-trace-point-for-damos-stat-per-apply-interval
+++ a/include/trace/events/damon.h
@@ -9,6 +9,47 @@
 #include <linux/types.h>
 #include <linux/tracepoint.h>
 
+TRACE_EVENT(damos_stat_after_apply_interval,
+
+	TP_PROTO(unsigned int context_idx, unsigned int scheme_idx,
+		struct damos_stat *stat),
+
+	TP_ARGS(context_idx, scheme_idx, stat),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, context_idx)
+		__field(unsigned int, scheme_idx)
+		__field(unsigned long, nr_tried)
+		__field(unsigned long, sz_tried)
+		__field(unsigned long, nr_applied)
+		__field(unsigned long, sz_applied)
+		__field(unsigned long, sz_ops_filter_passed)
+		__field(unsigned long, qt_exceeds)
+		__field(unsigned long, nr_snapshots)
+	),
+
+	TP_fast_assign(
+		__entry->context_idx = context_idx;
+		__entry->scheme_idx = scheme_idx;
+		__entry->nr_tried = stat->nr_tried;
+		__entry->sz_tried = stat->sz_tried;
+		__entry->nr_applied = stat->nr_applied;
+		__entry->sz_applied = stat->sz_applied;
+		__entry->sz_ops_filter_passed = stat->sz_ops_filter_passed;
+		__entry->qt_exceeds = stat->qt_exceeds;
+		__entry->nr_snapshots = stat->nr_snapshots;
+	),
+
+	TP_printk("ctx_idx=%u scheme_idx=%u nr_tried=%lu sz_tried=%lu "
+			"nr_applied=%lu sz_tried=%lu sz_ops_filter_passed=%lu "
+			"qt_exceeds=%lu nr_snapshots=%lu",
+			__entry->context_idx, __entry->scheme_idx,
+			__entry->nr_tried, __entry->sz_tried,
+			__entry->nr_applied, __entry->sz_applied,
+			__entry->sz_ops_filter_passed, __entry->qt_exceeds,
+			__entry->nr_snapshots)
+);
+
 TRACE_EVENT(damos_esz,
 
 	TP_PROTO(unsigned int context_idx, unsigned int scheme_idx,
--- a/mm/damon/core.c~mm-damon-core-add-trace-point-for-damos-stat-per-apply-interval
+++ a/mm/damon/core.c
@@ -2256,6 +2256,22 @@ static void damos_adjust_quota(struct da
 	quota->min_score = score;
 }
 
+static void damos_trace_stat(struct damon_ctx *c, struct damos *s)
+{
+	unsigned int cidx = 0, sidx = 0;
+	struct damos *siter;
+
+	if (!trace_damos_stat_after_apply_interval_enabled())
+		return;
+
+	damon_for_each_scheme(siter, c) {
+		if (siter == s)
+			break;
+		sidx++;
+	}
+	trace_damos_stat_after_apply_interval(cidx, sidx, &s->stat);
+}
+
 static void kdamond_apply_schemes(struct damon_ctx *c)
 {
 	struct damon_target *t;
@@ -2297,6 +2313,7 @@ static void kdamond_apply_schemes(struct
 			(s->apply_interval_us ? s->apply_interval_us :
 			 c->attrs.aggr_interval) / sample_interval;
 		s->last_applied = NULL;
+		damos_trace_stat(c, s);
 	}
 	mutex_unlock(&c->walk_control_lock);
 }
_

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-core-introduce-nr_snapshots-damos-stat.patch
mm-damon-sysfs-schemes-introduce-nr_snapshots-damos-stat-file.patch
docs-mm-damon-design-update-for-nr_snapshots-damos-stat.patch
docs-admin-guide-mm-damon-usage-update-for-nr_snapshots-damos-stat.patch
docs-abi-damon-update-for-nr_snapshots-damos-stat.patch
mm-damon-update-damos-kerneldoc-for-stat-field.patch
mm-damon-core-implement-max_nr_snapshots.patch
mm-damon-sysfs-schemes-implement-max_nr_snapshots-file.patch
docs-mm-damon-design-update-for-max_nr_snapshots.patch
docs-admin-guide-mm-damon-usage-update-for-max_nr_snapshots.patch
docs-abi-damon-update-for-max_nr_snapshots.patch
mm-damon-core-add-trace-point-for-damos-stat-per-apply-interval.patch