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

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Message-ID: <20251217235219.2750-1-sj@kernel.org>
Date: Wed, 17 Dec 2025 15:52:18 -0800
From: SeongJae Park <sj@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: SeongJae Park <sj@...nel.org>,
	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 Wed, 17 Dec 2025 17:48:51 -0500 Steven Rostedt <rostedt@...dmis.org> wrote:

> 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.

I also found checkpatch.pl shows warning for that.  I was ignoring that since I
was thinking that's just a recommendation.  But as I got more than one warning,
now I'd like to fix this.

Andrew, could you please add below attaching fixup patch?

> 
> > +			__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>

Thank you! :)


Thanks,
SJ

[...]

=== >8 ===
>From 67a7762ee1ade258c53913ea4ecf9bafd4746ea9 Mon Sep 17 00:00:00 2001
From: SeongJae Park <sj@...nel.org>
Date: Wed, 17 Dec 2025 15:42:06 -0800
Subject: [PATCH] mm/damon: do not break the string for damos_stat tracepoint

The format string for damos_stat tracepoint is broken up to multiple
lines.  Strings shouldn't be broken up due to the column limit, though.
Update the string to be put on a single line.

Suggested-by: Steven Rostedt (Google) <rostedt@...dmis.org>
Signed-off-by: SeongJae Park <sj@...nel.org>
---
 include/trace/events/damon.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h
index 24fc402ab3c8..bf25ee07cb48 100644
--- a/include/trace/events/damon.h
+++ b/include/trace/events/damon.h
@@ -40,9 +40,7 @@ TRACE_EVENT(damos_stat_after_apply_interval,
 		__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",
+	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,
-- 
2.47.3