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Message-ID: <20240521133029.83654-4-ben.gainey@arm.com>
Date: Tue, 21 May 2024 14:30:28 +0100
From: Ben Gainey <ben.gainey@....com>
To: peterz@...radead.org,
mingo@...hat.com,
acme@...nel.org,
namhyung@...nel.org
Cc: james.clark@....com,
mark.rutland@....com,
alexander.shishkin@...ux.intel.com,
jolsa@...nel.org,
irogers@...gle.com,
adrian.hunter@...el.com,
linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org,
Ben Gainey <ben.gainey@....com>
Subject: [PATCH v6 3/4] tools/perf: Correctly calculate sample period for inherited SAMPLE_READ values
Sample period calculation is updated to take into account the fact that
events with inherit+PERF_SAMPLE_READ+PERF_SAMPLE_TID should use
the TID in combination with the ID field in the read_format data to
identify which value represents the previous accumulated counter total used to
calculate the period delta since the last sample.
perf_sample_id is modified to support tracking per-thread
values, along with the existing global per-id values. In the
per-thread case, values are stored in a hash by TID within the
perf_sample_id, and are dynamically allocated as the number is not known
ahead of time.
deliver_sample_value is modified to correctly locate the previous
sample storage based on the attribute, stream id and thread id.
Signed-off-by: Ben Gainey <ben.gainey@....com>
---
tools/lib/perf/evsel.c | 41 ++++++++++++++++++++++
tools/lib/perf/include/internal/evsel.h | 45 +++++++++++++++++++++++--
tools/perf/util/session.c | 11 ++++--
3 files changed, 92 insertions(+), 5 deletions(-)
diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index f7abb879f416e..26f3d7ba0f267 100644
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -5,6 +5,7 @@
#include <perf/evsel.h>
#include <perf/cpumap.h>
#include <perf/threadmap.h>
+#include <linux/hash.h>
#include <linux/list.h>
#include <internal/evsel.h>
#include <linux/zalloc.h>
@@ -23,6 +24,7 @@ void perf_evsel__init(struct perf_evsel *evsel, struct perf_event_attr *attr,
int idx)
{
INIT_LIST_HEAD(&evsel->node);
+ INIT_LIST_HEAD(&evsel->per_stream_periods);
evsel->attr = *attr;
evsel->idx = idx;
evsel->leader = evsel;
@@ -531,10 +533,17 @@ int perf_evsel__alloc_id(struct perf_evsel *evsel, int ncpus, int nthreads)
void perf_evsel__free_id(struct perf_evsel *evsel)
{
+ struct perf_sample_id_period *pos, *n;
+
xyarray__delete(evsel->sample_id);
evsel->sample_id = NULL;
zfree(&evsel->id);
evsel->ids = 0;
+
+ perf_evsel_for_each_per_thread_period_safe(evsel, n, pos) {
+ list_del_init(&pos->node);
+ free(pos);
+ }
}
bool perf_evsel__attr_has_per_thread_sample_period(struct perf_evsel *evsel)
@@ -544,6 +553,38 @@ bool perf_evsel__attr_has_per_thread_sample_period(struct perf_evsel *evsel)
&& evsel->attr.inherit;
}
+u64 *perf_sample_id__get_period_storage(struct perf_sample_id *sid, u32 tid)
+{
+ struct hlist_head *head;
+ struct perf_sample_id_period *res;
+ int hash;
+
+ if (!sid->period_per_thread)
+ return &sid->period;
+
+ hash = hash_32(tid, PERF_SAMPLE_ID__HLIST_BITS);
+ head = &sid->periods[hash];
+
+ hlist_for_each_entry(res, head, hnode)
+ if (res->tid == tid)
+ return &res->period;
+
+ if (sid->evsel == NULL)
+ return NULL;
+
+ res = zalloc(sizeof(struct perf_sample_id_period));
+ if (res == NULL)
+ return NULL;
+
+ INIT_LIST_HEAD(&res->node);
+ res->tid = tid;
+
+ list_add_tail(&res->node, &sid->evsel->per_stream_periods);
+ hlist_add_head(&res->hnode, &sid->periods[hash]);
+
+ return &res->period;
+}
+
void perf_counts_values__scale(struct perf_counts_values *count,
bool scale, __s8 *pscaled)
{
diff --git a/tools/lib/perf/include/internal/evsel.h b/tools/lib/perf/include/internal/evsel.h
index f8de2bf89c76b..797dc9d782544 100644
--- a/tools/lib/perf/include/internal/evsel.h
+++ b/tools/lib/perf/include/internal/evsel.h
@@ -11,6 +11,32 @@
struct perf_thread_map;
struct xyarray;
+/**
+ * The per-thread accumulated period storage node.
+ */
+struct perf_sample_id_period {
+ struct list_head node;
+ struct hlist_node hnode;
+ /* Holds total ID period value for PERF_SAMPLE_READ processing. */
+ u64 period;
+ /* The TID that the values belongs to */
+ u32 tid;
+};
+
+/**
+ * perf_evsel_for_each_per_thread_period_safe - safely iterate thru all the
+ * per_stream_periods
+ * @evlist:perf_evsel instance to iterate
+ * @item: struct perf_sample_id_period iterator
+ * @tmp: struct perf_sample_id_period temp iterator
+ */
+#define perf_evsel_for_each_per_thread_period_safe(evsel, tmp, item) \
+ list_for_each_entry_safe(item, tmp, &(evsel)->per_stream_periods, node)
+
+
+#define PERF_SAMPLE_ID__HLIST_BITS 4
+#define PERF_SAMPLE_ID__HLIST_SIZE (1 << PERF_SAMPLE_ID__HLIST_BITS)
+
/*
* Per fd, to map back from PERF_SAMPLE_ID to evsel, only used when there are
* more than one entry in the evlist.
@@ -34,8 +60,18 @@ struct perf_sample_id {
pid_t machine_pid;
struct perf_cpu vcpu;
- /* Holds total ID period value for PERF_SAMPLE_READ processing. */
- u64 period;
+ union {
+ /*
+ * Holds total ID period value for PERF_SAMPLE_READ processing
+ * (when period is not per-thread).
+ */
+ u64 period;
+ /*
+ * Holds total ID period value for PERF_SAMPLE_READ processing
+ * (when period is per-thread).
+ */
+ struct hlist_head periods[PERF_SAMPLE_ID__HLIST_SIZE];
+ };
/*
* When inherit is combined with PERF_SAMPLE_READ, the period value is
@@ -65,6 +101,9 @@ struct perf_evsel {
u32 ids;
struct perf_evsel *leader;
+ /* Where period_per_thread is true, stores the per-thread values */
+ struct list_head per_stream_periods;
+
/* parse modifier helper */
int nr_members;
/*
@@ -97,4 +136,6 @@ void perf_evsel__free_id(struct perf_evsel *evsel);
bool perf_evsel__attr_has_per_thread_sample_period(struct perf_evsel *evsel);
+u64 *perf_sample_id__get_period_storage(struct perf_sample_id *sid, u32 tid);
+
#endif /* __LIBPERF_INTERNAL_EVSEL_H */
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 06d0bd7fb4599..2c66b730780ab 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1478,14 +1478,19 @@ static int deliver_sample_value(struct evlist *evlist,
{
struct perf_sample_id *sid = evlist__id2sid(evlist, v->id);
struct evsel *evsel;
+ u64 *storage = NULL;
if (sid) {
+ storage = perf_sample_id__get_period_storage(sid, sample->tid);
+ }
+
+ if (storage) {
sample->id = v->id;
- sample->period = v->value - sid->period;
- sid->period = v->value;
+ sample->period = v->value - *storage;
+ *storage = v->value;
}
- if (!sid || sid->evsel == NULL) {
+ if (!storage || sid->evsel == NULL) {
++evlist->stats.nr_unknown_id;
return 0;
}
--
2.45.1
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