mm/damon/core: add trace point for damos stat per apply interval

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>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.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: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h
index 852d725afea2ff53b3d3fb1c00fd9d3879273972..24fc402ab3c854b9f1e69a8b323735774ac9020b 100644 (file)
--- a/include/trace/events/damon.h
+++ b/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,

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 344773f53f6481ec36a7ba90801d38d02945150e..f4d83e12ba0e432e21b1fe70070227eaa1930754 100644 (file)
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2289,6 +2289,22 @@ static void damos_adjust_quota(struct damon_ctx *c, struct damos *s)
        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;
@@ -2330,6 +2346,7 @@ static void kdamond_apply_schemes(struct damon_ctx *c)
                        (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);
 }