Re: [RFC PATCH 16/19] mm/damon: trace probe_hits

[Steven Rostedt <rostedt@goodmis.org>]

On Sun, 26 Apr 2026 13:52:17 -0700
SeongJae Park <sj@kernel.org> wrote:

> Introduce a new tracepoint for exposing the per-region per-probe
> positive sample count via tracefs.
> 
> Signed-off-by: SeongJae Park <sj@kernel.org>
> ---
>  include/trace/events/damon.h | 41 ++++++++++++++++++++++++++++++++++++
>  mm/damon/core.c              |  1 +
>  2 files changed, 42 insertions(+)
> 
> diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h
> index 7e25f4469b81b..121d7bc3a2c27 100644
> --- a/include/trace/events/damon.h
> +++ b/include/trace/events/damon.h
> @@ -130,6 +130,47 @@ TRACE_EVENT(damon_monitor_intervals_tune,
>  	TP_printk("sample_us=%lu", __entry->sample_us)
>  );
>  
> +TRACE_EVENT(damon_aggregated_v2,
> +
> +	TP_PROTO(unsigned int target_id, struct damon_region *r,
> +		unsigned int nr_regions),
> +
> +	TP_ARGS(target_id, r, nr_regions),
> +
> +	TP_STRUCT__entry(
> +		__field(unsigned long, target_id)
> +		__field(unsigned int, nr_regions)

Move the nr_regions to after "end" as on 64 bit machines, this creates a 4
byte hole.

-- Steve


> +		__field(unsigned long, start)
> +		__field(unsigned long, end)
> +		__field(unsigned int, nr_accesses)
> +		__field(unsigned int, age)
> +		__field(unsigned char, probe_hit0)
> +		__field(unsigned char, probe_hit1)
> +		__field(unsigned char, probe_hit2)
> +		__field(unsigned char, probe_hit3)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->target_id = target_id;
> +		__entry->nr_regions = nr_regions;
> +		__entry->start = r->ar.start;
> +		__entry->end = r->ar.end;
> +		__entry->nr_accesses = r->nr_accesses;
> +		__entry->age = r->age;
> +		__entry->probe_hit0 = r->probe_hits[0];
> +		__entry->probe_hit1 = r->probe_hits[1];
> +		__entry->probe_hit2 = r->probe_hits[2];
> +		__entry->probe_hit3 = r->probe_hits[3];
> +	),
> +
> +	TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u %u %hhu %hhu %hhu %hhu",
> +			__entry->target_id, __entry->nr_regions,
> +			__entry->start, __entry->end,
> +			__entry->nr_accesses, __entry->age,
> +			__entry->probe_hit0, __entry->probe_hit1,
> +			__entry->probe_hit2, __entry->probe_hit3)
> +);
> +
>  TRACE_EVENT(damon_aggregated,
>  
>  	TP_PROTO(unsigned int target_id, struct damon_region *r,
> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index fe14971d72747..54834b74efef4 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -1924,6 +1924,7 @@ static void kdamond_reset_aggregated(struct damon_ctx *c)
>  			int i;
>  
>  			trace_damon_aggregated(ti, r, damon_nr_regions(t));
> +			trace_damon_aggregated_v2(ti, r, damon_nr_regions(t));
>  			damon_warn_fix_nr_accesses_corruption(r);
>  			r->last_nr_accesses = r->nr_accesses;
>  			r->nr_accesses = 0;