@@ -9,6 +9,45 @@
#include <linux/types.h>
#include <linux/tracepoint.h>
+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,
@@ -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);
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. Signed-off-by: SeongJae Park <sj@kernel.org> --- include/trace/events/damon.h | 39 ++++++++++++++++++++++++++++++++++++ mm/damon/core.c | 32 ++++++++++++++++++++++++++++- 2 files changed, 70 insertions(+), 1 deletion(-)