On Mon, 24 Feb 2020 13:30:42 +0100
SeongJae Park <sjpark@xxxxxxxxxx> wrote:
> From: SeongJae Park <sjpark@xxxxxxxxx>
>
> This commit adds a tracepoint for DAMON's result buffer writing. It is
> called for each writing of the DAMON results and print the result data.
> Therefore, it would be used to easily integrated with other tracepoint
> supporting tracers such as perf.
>
> Signed-off-by: SeongJae Park <sjpark@xxxxxxxxx>
I'm curious, why at the flush of rbuf rather than using a more structured trace
point for each of the writes into rbuf?
Seems it would make more sense to have a tracepoint for each record write out.
Probably at the level of each task, though might be more elegant to do it at the
level of each region within a task and duplicate the header stuff.
> ---
> include/trace/events/damon.h | 32 ++++++++++++++++++++++++++++++++
> mm/damon.c | 4 ++++
> 2 files changed, 36 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..fb33993620ce
> --- /dev/null
> +++ b/include/trace/events/damon.h
> @@ -0,0 +1,32 @@
> +/* 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/types.h>
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(damon_write_rbuf,
> +
> + TP_PROTO(void *buf, const ssize_t sz),
> +
> + TP_ARGS(buf, sz),
> +
> + TP_STRUCT__entry(
> + __dynamic_array(char, buf, sz)
> + ),
> +
> + TP_fast_assign(
> + memcpy(__get_dynamic_array(buf), buf, sz);
> + ),
> +
> + TP_printk("dat=%s", __print_hex(__get_dynamic_array(buf),
> + __get_dynamic_array_len(buf)))
> +);
> +
> +#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 facb1d7f121b..8faf3879f99e 100644
> --- a/mm/damon.c
> +++ b/mm/damon.c
> @@ -9,6 +9,8 @@
>
> #define pr_fmt(fmt) "damon: " fmt
>
> +#define CREATE_TRACE_POINTS
> +
> #include <linux/damon.h>
> #include <linux/debugfs.h>
> #include <linux/delay.h>
> @@ -20,6 +22,7 @@
> #include <linux/sched/mm.h>
> #include <linux/sched/task.h>
> #include <linux/slab.h>
> +#include <trace/events/damon.h>
>
> #define damon_get_task_struct(t) \
> (get_pid_task(find_vpid(t->pid), PIDTYPE_PID))
> @@ -553,6 +556,7 @@ static void damon_flush_rbuffer(struct damon_ctx *ctx)
> */
> static void damon_write_rbuf(struct damon_ctx *ctx, void *data, ssize_t size)
> {
> + trace_damon_write_rbuf(data, size);
> if (!ctx->rbuf_len || !ctx->rbuf)
> return;
> if (ctx->rbuf_offset + size > ctx->rbuf_len)
