On Fri, 4 Jul 2025 15:14:08 -0700
SeongJae Park <s...@kernel.org> wrote:
> Aim-oriented DAMOS quota auto-tuning is an important and recommended
> feature for DAMOS users. Add a trace event for the observability of the
> tuned quota and tuning itself.
>
> Signed-off-by: SeongJae Park <s...@kernel.org>
> ---
> include/trace/events/damon.h | 26 ++++++++++++++++++++++++++
> mm/damon/core.c | 20 +++++++++++++++++++-
> 2 files changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h
> index 32c611076023..36b2cdf47dce 100644
> --- a/include/trace/events/damon.h
> +++ b/include/trace/events/damon.h
> @@ -9,6 +9,32 @@
> #include <linux/types.h>
> #include <linux/tracepoint.h>
>
> +TRACE_EVENT_CONDITION(damos_esz,
> +
> + TP_PROTO(unsigned int context_idx, unsigned int scheme_idx,
> + unsigned long esz, bool do_trace),
> +
> + TP_ARGS(context_idx, scheme_idx, esz, do_trace),
> +
> + TP_CONDITION(do_trace),
Please explain to me why you are using a conditional here?
> +
> + TP_STRUCT__entry(
> + __field(unsigned int, context_idx)
> + __field(unsigned int, scheme_idx)
> + __field(unsigned long, esz)
> + ),
> +
> + TP_fast_assign(
> + __entry->context_idx = context_idx;
> + __entry->scheme_idx = scheme_idx;
> + __entry->esz = esz;
> + ),
> +
> + TP_printk("ctx_idx=%u scheme_idx=%u esz=%lu",
> + __entry->context_idx, __entry->scheme_idx,
> + __entry->esz)
> +);
> +
> TRACE_EVENT_CONDITION(damos_before_apply,
>
> TP_PROTO(unsigned int context_idx, unsigned int scheme_idx,
> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index 57a1ace4d10d..6019b8ec4bba 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -2011,12 +2011,26 @@ static void damos_set_effective_quota(struct
> damos_quota *quota)
> quota->esz = esz;
> }
>
> +static void damos_trace_esz(struct damon_ctx *c, struct damos *s,
> + struct damos_quota *quota)
> +{
> + unsigned int cidx = 0, sidx;
> + struct damos *siter;
> +
> + damon_for_each_scheme(siter, c) {
> + if (siter == s)
> + break;
> + sidx++;
> + }
> + trace_damos_esz(cidx, sidx, quota->esz, true);
It's set to true, so it's not even a conditional anymore. The compiler
will likely optimize it out!
-- Steve
> +}
> +
> static void damos_adjust_quota(struct damon_ctx *c, struct damos *s)
> {
> struct damos_quota *quota = &s->quota;
> struct damon_target *t;
> struct damon_region *r;
> - unsigned long cumulated_sz;
> + unsigned long cumulated_sz, cached_esz;
> unsigned int score, max_score = 0;
>
> if (!quota->ms && !quota->sz && list_empty("a->goals))
> @@ -2030,7 +2044,11 @@ static void damos_adjust_quota(struct damon_ctx *c,
> struct damos *s)
> quota->total_charged_sz += quota->charged_sz;
> quota->charged_from = jiffies;
> quota->charged_sz = 0;
> + if (trace_damos_esz_enabled())
> + cached_esz = quota->esz;
> damos_set_effective_quota(quota);
> + if (trace_damos_esz_enabled() && quota->esz != cached_esz)
> + damos_trace_esz(c, s, quota);
> }
>
> if (!c->ops.get_scheme_score)
