From c603c630b509d690d470b9b49eb96f40482f47d5 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Wed, 13 Sep 2023 02:20:49 +0000 Subject: [PATCH] mm/damon/core: add a tracepoint for damos apply target regions Patch series "mm/damon: add a tracepoint for damos apply target regions", v2. DAMON provides damon_aggregated tracepoint to let users record full monitoring results. Sometimes, users need to record monitoring results of specific pattern. DAMOS tried regions directory of DAMON sysfs interface allows it, but the interface is mainly designed for snapshots and therefore would be inefficient for such recording. Implement yet another tracepoint for efficient support of the usecase. This patch (of 2): DAMON provides damon_aggregated tracepoint, which exposes details of each region and its access monitoring results. It is useful for getting whole monitoring results, e.g., for recording purposes. For investigations of DAMOS, DAMON Sysfs interface provides DAMOS statistics and tried_regions directory. But, those provides only statistics and snapshots. If the scheme is frequently applied and if the user needs to know every detail of DAMOS behavior, the snapshot-based interface could be insufficient and expensive. As a last resort, userspace users need to record the all monitoring results via damon_aggregated tracepoint and simulate how DAMOS would worked. It is unnecessarily complicated. DAMON kernel API users, meanwhile, can do that easily via before_damos_apply() callback field of 'struct damon_callback', though. Add a tracepoint that will be called just after before_damos_apply() callback for more convenient investigations of DAMOS. The tracepoint exposes all details about each regions, similar to damon_aggregated tracepoint. Please note that DAMOS is currently not only for memory management but also for query-like efficient monitoring results retrievals (when 'stat' action is used). Until now, only statistics or snapshots were supported. Addition of this tracepoint allows efficient full recording of DAMOS-based filtered monitoring results. Link: https://lkml.kernel.org/r/20230913022050.2109-1-sj@kernel.org Link: https://lkml.kernel.org/r/20230913022050.2109-2-sj@kernel.org Signed-off-by: SeongJae Park Reviewed-by: Steven Rostedt (Google) [tracing] Cc: Jonathan Corbet Signed-off-by: Andrew Morton --- include/trace/events/damon.h | 39 ++++++++++++++++++++++++++++++++++++ mm/damon/core.c | 32 ++++++++++++++++++++++++++++- 2 files changed, 70 insertions(+), 1 deletion(-) diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h index 0b8d13bde17a..19930bb7af9a 100644 --- a/include/trace/events/damon.h +++ b/include/trace/events/damon.h @@ -9,6 +9,45 @@ #include #include +TRACE_EVENT_CONDITION(damos_before_apply, + + TP_PROTO(unsigned int context_idx, unsigned int scheme_idx, + unsigned int target_idx, struct damon_region *r, + unsigned int nr_regions, bool do_trace), + + TP_ARGS(context_idx, target_idx, scheme_idx, r, nr_regions, do_trace), + + TP_CONDITION(do_trace), + + TP_STRUCT__entry( + __field(unsigned int, context_idx) + __field(unsigned int, scheme_idx) + __field(unsigned long, target_idx) + __field(unsigned long, start) + __field(unsigned long, end) + __field(unsigned int, nr_accesses) + __field(unsigned int, age) + __field(unsigned int, nr_regions) + ), + + TP_fast_assign( + __entry->context_idx = context_idx; + __entry->scheme_idx = scheme_idx; + __entry->target_idx = target_idx; + __entry->start = r->ar.start; + __entry->end = r->ar.end; + __entry->nr_accesses = r->nr_accesses; + __entry->age = r->age; + __entry->nr_regions = nr_regions; + ), + + TP_printk("ctx_idx=%u scheme_idx=%u target_idx=%lu nr_regions=%u %lu-%lu: %u %u", + __entry->context_idx, __entry->scheme_idx, + __entry->target_idx, __entry->nr_regions, + __entry->start, __entry->end, + __entry->nr_accesses, __entry->age) +); + TRACE_EVENT(damon_aggregated, TP_PROTO(unsigned int target_id, struct damon_region *r, diff --git a/mm/damon/core.c b/mm/damon/core.c index ca631dd88b33..3ca34a252a3c 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -950,6 +950,33 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, struct timespec64 begin, end; unsigned long sz_applied = 0; int err = 0; + /* + * We plan to support multiple context per kdamond, as DAMON sysfs + * implies with 'nr_contexts' file. Nevertheless, only single context + * per kdamond is supported for now. So, we can simply use '0' context + * index here. + */ + unsigned int cidx = 0; + struct damos *siter; /* schemes iterator */ + unsigned int sidx = 0; + struct damon_target *titer; /* targets iterator */ + unsigned int tidx = 0; + bool do_trace = false; + + /* get indices for trace_damos_before_apply() */ + if (trace_damos_before_apply_enabled()) { + damon_for_each_scheme(siter, c) { + if (siter == s) + break; + sidx++; + } + damon_for_each_target(titer, c) { + if (titer == t) + break; + tidx++; + } + do_trace = true; + } if (c->ops.apply_scheme) { if (quota->esz && quota->charged_sz + sz > quota->esz) { @@ -964,8 +991,11 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, ktime_get_coarse_ts64(&begin); if (c->callback.before_damos_apply) err = c->callback.before_damos_apply(c, t, r, s); - if (!err) + if (!err) { + trace_damos_before_apply(cidx, sidx, tidx, r, + damon_nr_regions(t), do_trace); sz_applied = c->ops.apply_scheme(c, t, r, s); + } ktime_get_coarse_ts64(&end); quota->total_charged_ns += timespec64_to_ns(&end) - timespec64_to_ns(&begin);