linux-kernel - Re: [PATCH v19 08/15] mm/damon: Add a tracepoint

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Message-ID: <20200804180147.16d34809@oasis.local.home>
Date:   Tue, 4 Aug 2020 18:01:47 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     SeongJae Park <sjpark@...zon.com>
Cc:     <akpm@...ux-foundation.org>, SeongJae Park <sjpark@...zon.de>,
        <Jonathan.Cameron@...wei.com>, <aarcange@...hat.com>,
        <acme@...nel.org>, <alexander.shishkin@...ux.intel.com>,
        <amit@...nel.org>, <benh@...nel.crashing.org>,
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        <cai@....pw>, <colin.king@...onical.com>, <corbet@....net>,
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        <yang.shi@...ux.alibaba.com>, <ying.huang@...el.com>,
        <linux-damon@...zon.com>, <linux-mm@...ck.org>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v19 08/15] mm/damon: Add a tracepoint

On Tue, 4 Aug 2020 11:14:09 +0200
SeongJae Park <sjpark@...zon.com> wrote:

> From: SeongJae Park <sjpark@...zon.de>
> 
> This commit adds a tracepoint for DAMON.  It traces the monitoring
> results of each region for each aggregation interval.  Using this, DAMON
> can easily integrated with tracepoints supporting tools such as perf.
> 
> Signed-off-by: SeongJae Park <sjpark@...zon.de>
> Reviewed-by: Leonard Foerster <foersleo@...zon.de>
> ---
>  include/trace/events/damon.h | 43 ++++++++++++++++++++++++++++++++++++
>  mm/damon.c                   |  4 ++++
>  2 files changed, 47 insertions(+)
>  create mode 100644 include/trace/events/damon.h
> 
> diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h
> new file mode 100644
> index 000000000000..2f422f4f1fb9
> --- /dev/null
> +++ b/include/trace/events/damon.h
> @@ -0,0 +1,43 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM damon
> +
> +#if !defined(_TRACE_DAMON_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_DAMON_H
> +
> +#include <linux/damon.h>
> +#include <linux/types.h>
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(damon_aggregated,
> +
> +	TP_PROTO(struct damon_target *t, struct damon_region *r,
> +		unsigned int nr_regions),
> +
> +	TP_ARGS(t, r, nr_regions),
> +
> +	TP_STRUCT__entry(
> +		__field(unsigned long, target_id)
> +		__field(unsigned int, nr_regions)
> +		__field(unsigned long, start)
> +		__field(unsigned long, end)
> +		__field(unsigned int, nr_accesses)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->target_id = t->id;
> +		__entry->nr_regions = nr_regions;
> +		__entry->start = r->ar.start;
> +		__entry->end = r->ar.end;
> +		__entry->nr_accesses = r->nr_accesses;
> +	),
> +
> +	TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u",
> +			__entry->target_id, __entry->nr_regions,
> +			__entry->start, __entry->end, __entry->nr_accesses)
> +);
> +
> +#endif /* _TRACE_DAMON_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/mm/damon.c b/mm/damon.c
> index b3420ba97fd2..65e65e779313 100644
> --- a/mm/damon.c
> +++ b/mm/damon.c
> @@ -20,6 +20,8 @@
>  
>  #define pr_fmt(fmt) "damon: " fmt
>  
> +#define CREATE_TRACE_POINTS
> +
>  #include <linux/damon.h>
>  #include <linux/delay.h>
>  #include <linux/kthread.h>
> @@ -31,6 +33,7 @@
>  #include <linux/sched/mm.h>
>  #include <linux/sched/task.h>
>  #include <linux/slab.h>

It's best to place the #define CREATE_TRACE_POINTS here, so that it
doesn't cause any side effects when including the other headers.

Other than that:

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

-- Steve


> +#include <trace/events/damon.h>
>  
>  /* Minimal region size.  Every damon_region is aligned by this. */
>  #define MIN_REGION PAGE_SIZE
> @@ -856,6 +859,7 @@ static void kdamond_reset_aggregated(struct damon_ctx *c)
>  			damon_write_rbuf(c, &r->ar.end, sizeof(r->ar.end));
>  			damon_write_rbuf(c, &r->nr_accesses,
>  					sizeof(r->nr_accesses));
> +			trace_damon_aggregated(t, r, nr);
>  			r->nr_accesses = 0;
>  		}
>  	}