linux-kernel - Re: [PATCH 12/12] mm/damon/core: add trace point for damos stat per apply interval

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Message-ID: <20251217174851.28e7c4e5@gandalf.local.home>
Date: Wed, 17 Dec 2025 17:48:51 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: SeongJae Park <sj@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 damon@...ts.linux.dev, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH 12/12] mm/damon/core: add trace point for damos stat per
 apply interval

On Tue, 16 Dec 2025 00:01:25 -0800
SeongJae Park <sj@...nel.org> wrote:

> +	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",

Nit, but it's been stated that strings should not be broken up because of
the column limit.

> +			__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 8908aec6670f..68dd2f7acba2 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -2256,6 +2256,22 @@ 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;

Other than that, from a tracing POV:

Reviewed-by: Steven Rostedt (Google) <rostedt@...dmis.org>

-- Steve

> +
> +	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 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);
>  }