From: Kunwu Chan <[email protected]> Wire the observe_*() calls into the DAMON hot paths: vaddr access-check overflow handlers report into the per-CPU ring, and the kdamond drain matches each report against the target whose tgid owns it. The observe calls are pure side-effect statistics (no-ops under CONFIG_DAMON_PERF_OBSERVE=n), so the switch never changes DAMON matching semantics. The vaddr teardown frees the per-event cpu_state array.
Read ring->tail once with READ_ONCE in damon_report_access() and reuse the cached value for the peak-occupancy estimate, avoiding a torn read and a compiler reload on the producer side. Co-developed-by: Lian Wang <[email protected]> Signed-off-by: Lian Wang <[email protected]> Signed-off-by: Kunwu Chan <[email protected]> --- mm/damon/core.c | 129 +++++++++++++++++++++++++++++++++++++---------- mm/damon/vaddr.c | 104 +++++++++++++++++++++++++++++++++++--- 2 files changed, 199 insertions(+), 34 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index 609d627e2b33..377f07122fb0 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -21,6 +21,7 @@ /* for damon_get_folio() used by node eligible memory metrics */ #include "ops-common.h" +#include "perf/perf.h" #define CREATE_TRACE_POINTS #include <trace/events/damon.h> @@ -2243,24 +2244,41 @@ void damon_report_access(struct damon_access_report *report) preempt_disable(); if (local_inc_return(this_cpu_ptr(&damon_report_ring_busy)) != 1) { /* NMI nested on a process-context producer; drop. */ - trace_damon_perf_ring_overflow(smp_processor_id()); +#ifdef CONFIG_DAMON_PERF_OBSERVE + damon_perf_observe_ring_overflow(smp_processor_id()); +#endif /* CONFIG_DAMON_PERF_OBSERVE */ goto out; } ring = this_cpu_ptr(&damon_report_rings); head = ring->head; next = (head + 1) & DAMON_REPORT_RING_MASK; + { + unsigned int tail = READ_ONCE(ring->tail); - if (next == READ_ONCE(ring->tail)) { - trace_damon_perf_ring_overflow(smp_processor_id()); - goto out; - } + if (next == tail) { +#ifdef CONFIG_DAMON_PERF_OBSERVE + damon_perf_observe_ring_overflow(smp_processor_id()); +#endif /* CONFIG_DAMON_PERF_OBSERVE */ + goto out; + } - ring->entries[head] = *report; - ring->entries[head].report_jiffies = jiffies; - smp_wmb(); /* publish entry before head advance */ - WRITE_ONCE(ring->head, next); - WRITE_ONCE(*this_cpu_ptr(&damon_ring_pending), 1); + ring->entries[head] = *report; + ring->entries[head].report_jiffies = jiffies; + smp_wmb(); /* publish entry before head advance */ + WRITE_ONCE(ring->head, next); + WRITE_ONCE(*this_cpu_ptr(&damon_ring_pending), 1); +#ifdef CONFIG_DAMON_PERF_OBSERVE + damon_perf_observe_ring_enqueue(); + /* + * Track peak occupancy for health evaluation. + * next is the new head; tail was read before enqueue + * (may be slightly stale — acceptable for a peak estimate). + */ + damon_perf_observe_ring_peak( + (next - tail) & DAMON_REPORT_RING_MASK); +#endif /* CONFIG_DAMON_PERF_OBSERVE */ + } out: local_dec(this_cpu_ptr(&damon_report_ring_busy)); preempt_enable(); @@ -2276,6 +2294,9 @@ void damon_report_page_fault(struct vm_fault *vmf, bool huge_pmd) .tid = current->pid, .tgid = task_tgid_nr(current), .is_write = vmf->flags & FAULT_FLAG_WRITE, +#ifdef CONFIG_DAMON_PERF_OBSERVE + .source = DAMON_REPORT_SRC_PAGE_FAULT, +#endif /* CONFIG_DAMON_PERF_OBSERVE */ }; if (huge_pmd) @@ -3917,8 +3938,16 @@ static bool damon_sample_filter_out(struct damon_access_report *report, return !filter->allow; } -static void kdamond_apply_access_report(struct damon_access_report *report, - struct damon_target *t, +/* + * Try to apply one access report to a target's region snapshot. + * + * Caller has already resolved tgid (for pid-based monitoring), so this + * function only does address-to-region matching. Miss reasons for + * trace_damon_perf_report_missed use enum damon_report_miss_reason. + * + * Return: true if the report fell inside a known region, false otherwise. + */ +static bool kdamond_apply_access_report(struct damon_access_report *report, struct damon_region **regions, unsigned int nr_regions, struct damon_ctx *ctx) { @@ -3926,13 +3955,7 @@ static void kdamond_apply_access_report(struct damon_access_report *report, unsigned long addr; int left, right, mid; - if (damon_target_has_pid(ctx)) { - if (pid_nr(t->pid) != report->tgid) - return; - addr = report->vaddr; - } else { - addr = report->paddr; - } + addr = damon_target_has_pid(ctx) ? report->vaddr : report->paddr; /* Binary search the snapshot for the region containing addr. */ left = 0; @@ -3951,17 +3974,27 @@ static void kdamond_apply_access_report(struct damon_access_report *report, } } - if (!r) - return; + if (!r) { + damon_perf_observe_miss(addr, report->cpu, + DAMON_REPORT_MISS_NOREGION); + return false; + } /* Reject reports straddling a region boundary. */ - if (addr + report->size > r->ar.end) - return; + if (addr + report->size > r->ar.end) { + damon_perf_observe_miss(addr, report->cpu, + DAMON_REPORT_MISS_BOUNDARY); + return false; + } if (!r->access_reported) { damon_update_region_access_rate(r, true, &ctx->attrs); r->access_reported = true; + damon_perf_observe_update(report->cpu); } + damon_perf_observe_match(addr, report->cpu); + return true; } + static unsigned int kdamond_apply_zero_access_report(struct damon_ctx *ctx) { struct damon_target *t; @@ -4045,6 +4078,7 @@ static unsigned int kdamond_check_reported_accesses(struct damon_ctx *ctx) struct damon_target_lookup *tbl; unsigned int nr_targets = 0; unsigned int i; + unsigned int total_reports = 0, matched_reports = 0; tbl = damon_build_target_lookup(ctx, &nr_targets); if (!tbl) { @@ -4077,6 +4111,10 @@ static unsigned int kdamond_check_reported_accesses(struct damon_ctx *ctx) while (tail != head) { struct damon_access_report *report = &ring->entries[tail]; + bool applied = false; + + /* Count every entry removed from the ring */ + damon_perf_observe_ring_dequeue(report->cpu); if (time_before(report->report_jiffies, jiffies - usecs_to_jiffies( @@ -4085,16 +4123,52 @@ static unsigned int kdamond_check_reported_accesses(struct damon_ctx *ctx) if (damon_sample_filter_out(report, &ctx->sample_control)) goto next; - for (i = 0; i < nr_targets; i++) - kdamond_apply_access_report(report, - tbl[i].t, + /* + * For pid-based monitoring, resolve tgid to the + * single matching target before calling + * kdamond_apply_access_report(), avoiding a + * spurious miss tracepoint for every non-matching + * target. + */ + if (damon_target_has_pid(ctx)) { + for (i = 0; i < nr_targets; i++) { + if (pid_nr(tbl[i].t->pid) == + report->tgid) { + applied = + kdamond_apply_access_report( + report, + tbl[i].regions, + tbl[i].nr_regions, + ctx); + break; + } + } + if (!applied && i == nr_targets) + damon_perf_observe_miss( + report->vaddr, + report->cpu, + DAMON_REPORT_MISS_TGID); + } else { + for (i = 0; i < nr_targets; i++) + applied |= + kdamond_apply_access_report( + report, tbl[i].regions, tbl[i].nr_regions, ctx); + } + total_reports++; + if (applied) + matched_reports++; + next: tail = (tail + 1) & DAMON_REPORT_RING_MASK; } WRITE_ONCE(ring->tail, tail); } + + if (total_reports) + damon_perf_observe_drain(total_reports, matched_reports); + /* For nr_accesses_bp, absence of access should also be reported. */ return kdamond_apply_zero_access_report(ctx); } @@ -4158,8 +4232,9 @@ static int kdamond_fn(void *data) ctx->passed_sample_intervals++; if (!list_empty(&ctx->perf_events) || - ctx->sample_control.primitives_enabled.page_fault) + ctx->sample_control.primitives_enabled.page_fault) { max_nr_accesses = kdamond_check_reported_accesses(ctx); + } else if (ctx->ops.check_accesses) max_nr_accesses = ctx->ops.check_accesses(ctx); if (ctx->ops.apply_probes) diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c index 73fcea91afa0..a68c7262d533 100644 --- a/mm/damon/vaddr.c +++ b/mm/damon/vaddr.c @@ -17,6 +17,8 @@ #include <linux/pagewalk.h> #include <linux/sched/mm.h> +#include "perf/perf.h" + #include "../internal.h" #include "ops-common.h" @@ -975,13 +977,49 @@ static void damon_perf_overflow_vaddr(struct perf_event *perf_event, struct perf_sample_data *data, struct pt_regs *regs) { struct damon_access_report report; + u64 data_src_val; + u64 period_val; + + /* + * Observe every hardware sample through the unified API. + * + * reason encodes why a sample was dropped at the handler level: + * 0 = valid, queued to ring + * 1 = data == NULL + * 2 = addr == 0 (PMU did not populate data->addr) + * 3 = kernel address (addr >= TASK_SIZE) + */ + if (!data) { + damon_perf_observe_sample(0, 0, 0, + smp_processor_id(), 1, 0, + perf_event->attr.sample_type); + return; + } - if (!data || !data->addr) + data_src_val = data->data_src.val; + period_val = data->period; + + if (!data->addr) { + damon_perf_observe_sample(0, data_src_val, period_val, + smp_processor_id(), 2, + data->sample_flags, + perf_event->attr.sample_type); return; + } /* Drop kernel-VA hits -- only user-space VAs land in damon vaddr regions. */ - if (data->addr >= TASK_SIZE) + if (data->addr >= TASK_SIZE) { + damon_perf_observe_sample(data->addr, data_src_val, period_val, + smp_processor_id(), 3, + data->sample_flags, + perf_event->attr.sample_type); return; + } + + damon_perf_observe_sample(data->addr, data_src_val, period_val, + smp_processor_id(), 0, + data->sample_flags, + perf_event->attr.sample_type); report = (struct damon_access_report){ .vaddr = data->addr & PAGE_MASK, @@ -990,6 +1028,9 @@ static void damon_perf_overflow_vaddr(struct perf_event *perf_event, .tid = current->pid, .tgid = current->tgid, .is_write = !!(data->data_src.mem_op & PERF_MEM_OP_STORE), +#ifdef CONFIG_DAMON_PERF_OBSERVE + .source = DAMON_REPORT_SRC_PERF_OVERFLOW, +#endif /* CONFIG_DAMON_PERF_OBSERVE */ }; damon_report_access(&report); } @@ -998,9 +1039,18 @@ static void damon_perf_overflow_paddr(struct perf_event *perf_event, struct perf_sample_data *data, struct pt_regs *regs) { struct damon_access_report report; + u64 data_src_val; + u64 period_val; - if (!data) + if (!data) { + damon_perf_observe_sample(0, 0, 0, + smp_processor_id(), 1, 0, + perf_event->attr.sample_type); return; + } + + data_src_val = data->data_src.val; + period_val = data->period; /* * AMD IBS Op only populates data->phys_addr when @@ -1008,14 +1058,27 @@ static void damon_perf_overflow_paddr(struct perf_event *perf_event, * carries a stale value. Gate on sample_flags rather than testing * phys_addr for zero (which would also drop legitimate page 0). */ - if (!(data->sample_flags & PERF_SAMPLE_PHYS_ADDR)) + if (!(data->sample_flags & PERF_SAMPLE_PHYS_ADDR)) { + damon_perf_observe_sample(0, data_src_val, + period_val, smp_processor_id(), 4, + data->sample_flags, + perf_event->attr.sample_type); return; + } + + damon_perf_observe_sample(data->phys_addr, data_src_val, period_val, + smp_processor_id(), 0, + data->sample_flags, + perf_event->attr.sample_type); report = (struct damon_access_report){ .paddr = data->phys_addr & PAGE_MASK, .size = PAGE_SIZE, .cpu = smp_processor_id(), .is_write = !!(data->data_src.mem_op & PERF_MEM_OP_STORE), +#ifdef CONFIG_DAMON_PERF_OBSERVE + .source = DAMON_REPORT_SRC_PERF_OVERFLOW, +#endif /* CONFIG_DAMON_PERF_OBSERVE */ }; damon_report_access(&report); } @@ -1070,6 +1133,8 @@ static int damon_perf_cpu_online(unsigned int cpu, struct hlist_node *node) if (!perf) return 0; + damon_perf_observe_event_created(event, cpu); + damon_perf_event_init_attr(event, &attr); /* @@ -1092,14 +1157,20 @@ static int damon_perf_cpu_online(unsigned int cpu, struct hlist_node *node) return 0; /* never block CPU online */ } *per_cpu_ptr(perf->event, cpu) = perf_event; + + damon_perf_observe_event_bound(event, cpu, perf_event); + /* * Late-online CPU after the substrate is armed: events are created * with attr.disabled = 1 and would otherwise stay quiescent on this * CPU until the next arm walk. Enable here so coverage matches the * already-online CPUs. */ - if (event->ctx && READ_ONCE(event->ctx->perf_events_active)) + if (event->ctx && READ_ONCE(event->ctx->perf_events_active)) { perf_event_enable(perf_event); + damon_perf_observe_event_enabled(event, cpu, + perf_event->state, perf_event->oncpu); + } return 0; } @@ -1115,6 +1186,7 @@ static int damon_perf_cpu_offline(unsigned int cpu, struct hlist_node *node) perf_event = per_cpu(*perf->event, cpu); if (perf_event) { + damon_perf_observe_event_destroyed(event, cpu); perf_event_disable(perf_event); perf_event_release_kernel(perf_event); *per_cpu_ptr(perf->event, cpu) = NULL; @@ -1133,8 +1205,12 @@ void damon_perf_event_arm(struct damon_perf_event *event) for_each_online_cpu(cpu) { perf_event = *per_cpu_ptr(perf->event, cpu); - if (perf_event) + if (perf_event) { perf_event_enable(perf_event); + damon_perf_observe_event_enabled(event, cpu, + perf_event->state, + perf_event->oncpu); + } } } @@ -1149,8 +1225,11 @@ void damon_perf_event_disarm(struct damon_perf_event *event) for_each_online_cpu(cpu) { perf_event = *per_cpu_ptr(perf->event, cpu); - if (perf_event) + if (perf_event) { perf_event_disable(perf_event); + damon_perf_observe_event_disabled(event, cpu, + perf_event->state); + } } } @@ -1192,6 +1271,7 @@ int damon_perf_init(struct damon_ctx *ctx, struct damon_perf_event *event) return 0; free_event: + damon_perf_observe_event_free(event); free_percpu(perf->event); free_perf: kfree(perf); @@ -1203,6 +1283,8 @@ void damon_perf_cleanup(struct damon_ctx *ctx, struct damon_perf_event *event) { struct damon_perf *perf = event->priv; + damon_perf_observe_event_free(event); + if (!perf) return; @@ -1244,6 +1326,14 @@ static int __init damon_va_initcall(void) if (err < 0) return err; damon_perf_cpuhp_state = err; + +#ifdef CONFIG_DAMON_PERF_OBSERVE + err = damon_perf_framework_init(); + if (err < 0) + pr_warn("damon-perf: framework init failed, observability unavailable: %d\n", + err); + /* Non-fatal: vaddr/fvaddr ops still register. */ +#endif /* CONFIG_DAMON_PERF_OBSERVE */ #endif err = damon_register_ops(&ops); -- 2.43.0
