[PATCH v11 0/2] tools/perf: Support PERF_SAMPLE_READ with inherit

[PATCH v11 0/2] tools/perf: Support PERF_SAMPLE_READ with inherit

[Ben Gainey]

This revision of this change splits out the tools/perf changes requested 
by Namhyung Kim for my previous work to enable PERF_SAMPLE READ with inherit (see 
https://lore.kernel.org/linux-perf-users/20240730084417.7693-1-ben.gainey@arm.com/ ) 
as the kernel side changes have been picked up by Peter Zijlstra.

Changes since v10:
 - Fixed a formatting nit

Changes since v9:
 - Split out tools/perf patches only
 - Fixed system-wide mode in `perf record` to not set the inherit bit.

Changes since v8:
 - Rebase on v6.11-rc1

Changes since v7:
 - Rebase on v6.10-rc3
 - Respond to Peter Zijlstra's feedback:
 - Renamed nr_pending to nr_no_switch_fast and merged in nr_inherit_read
   which otherwise had overlapping use
 - Updated some of the commit messages to provide better justifications
   of usecase, behavioural changes and so on
 - Cleanup perf_event_count/_cumulative
 - Make it explicit that the sampling event decides whether or not the
   per-thread value is given in read_format for PERF_RECORD_SAMPLE and
   PERF_RECORD_READ; updated tools to account for this.

Changes since v6:
 - Rebase on v6.10-rc2
 - Make additional "perf test" tests succeed / skip based on kernel
   version as per feedback from Namhyung.

Changes since v5:
 - Rebase on v6.9
 - Cleanup feedback from Namhyung Kim

Changes since v4:
 - Rebase on v6.9-rc1
 - Removed the dependency on inherit_stat that was previously assumed
   necessary as per feedback from Namhyung Kim.
 - Fixed an incorrect use of zfree instead of free in the tools leading
   to an abort on tool shutdown.
 - Additional test coverage improvements added to perf test.
 - Cleaned up the remaining bit of irrelevant change missed between v3
   and v4.

Changes since v3:
 - Cleaned up perf test data changes incorrectly included into this
   series from elsewhere.

Changes since v2:
 - Rebase on v6.8
 - Respond to James Clarke's feedback; fixup some typos and move some
   repeated checks into a helper macro.
 - Cleaned up checkpatch lints.
 - Updated perf test; fixed evsel handling so that existing tests pass
   and added new tests to cover the new behaviour.

Changes since v1:
 - Rebase on v6.8-rc1
 - Fixed value written into sample after child exists.
 - Modified handling of switch-out so that context with these events
   take the slow path, so that the per-event/per-thread PMU state is
   correctly switched.
 - Modified perf tools to support this mode of operation.

Ben Gainey (2):
  tools/perf: Correctly calculate sample period for inherited
    SAMPLE_READ values
  tools/perf: Allow inherit + PERF_SAMPLE_READ when opening events

 tools/lib/perf/evsel.c                        | 48 ++++++++++++++
 tools/lib/perf/include/internal/evsel.h       | 63 ++++++++++++++++++-
 tools/perf/tests/attr/README                  |  2 +
 tools/perf/tests/attr/test-record-C0          |  2 +
 tools/perf/tests/attr/test-record-dummy-C0    |  2 +-
 .../tests/attr/test-record-group-sampling     |  3 +-
 .../tests/attr/test-record-group-sampling1    | 51 +++++++++++++++
 .../tests/attr/test-record-group-sampling2    | 61 ++++++++++++++++++
 tools/perf/tests/attr/test-record-group2      |  1 +
 ...{test-record-group2 => test-record-group3} | 10 +--
 tools/perf/util/evsel.c                       | 21 ++++++-
 tools/perf/util/evsel.h                       |  1 +
 tools/perf/util/session.c                     | 25 +++++---
 13 files changed, 271 insertions(+), 19 deletions(-)
 create mode 100644 tools/perf/tests/attr/test-record-group-sampling1
 create mode 100644 tools/perf/tests/attr/test-record-group-sampling2
 copy tools/perf/tests/attr/{test-record-group2 => test-record-group3} (81%)

-- 
2.45.2

[PATCH v11 1/2] tools/perf: Correctly calculate sample period for inherited SAMPLE_READ values

[Ben Gainey]

Sample period calculation in deliver_sample_value is updated to
calculate the per-thread period delta for events that are inherit +
PERF_SAMPLE_READ. When the sampling event has this configuration, the
read_format.id is used with the tid from the sample to lookup the
storage of the previously accumulated counter total before calculating
the delta. All existing valid configurations where read_format.value
represents some global value continue to use just the read_format.id to
locate the storage of the previously accumulated total.

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.

Signed-off-by: Ben Gainey <ben.gainey@arm.com>
---
 tools/lib/perf/evsel.c                  | 48 +++++++++++++++++++
 tools/lib/perf/include/internal/evsel.h | 63 ++++++++++++++++++++++++-
 tools/perf/util/session.c               | 25 ++++++----
 3 files changed, 126 insertions(+), 10 deletions(-)

diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index c07160953224..c475319e2e41 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 +533,56 @@ 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)
+{
+	return (evsel->attr.sample_type & PERF_SAMPLE_READ) &&
+		(evsel->attr.sample_type & PERF_SAMPLE_TID) &&
+		evsel->attr.inherit;
+}
+
+u64 *perf_sample_id__get_period_storage(struct perf_sample_id *sid, u32 tid, bool per_thread)
+{
+	struct hlist_head *head;
+	struct perf_sample_id_period *res;
+	int hash;
+
+	if (!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,
diff --git a/tools/lib/perf/include/internal/evsel.h b/tools/lib/perf/include/internal/evsel.h
index 5cd220a61962..ea78defa77d0 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 +60,32 @@ struct perf_sample_id {
 	pid_t			 machine_pid;
 	struct perf_cpu		 vcpu;
 
-	/* Holds total ID period value for PERF_SAMPLE_READ processing. */
-	u64			 period;
+	/*
+	 * Per-thread, and global event counts are mutually exclusive:
+	 * Whilst it is possible to combine events into a group with differing
+	 * values of PERF_SAMPLE_READ, it is not valid to have inconsistent
+	 * values for `inherit`. Therefore it is not possible to have a
+	 * situation where a per-thread event is sampled as a global event;
+	 * all !inherit groups are global, and all groups where the sampling
+	 * event is inherit + PERF_SAMPLE_READ will be per-thread. Any event
+	 * that is part of such a group that is inherit but not PERF_SAMPLE_READ
+	 * will be read as per-thread. If such an event can also trigger a
+	 * sample (such as with sample_period > 0) then it will not cause
+	 * `read_format` to be included in its PERF_RECORD_SAMPLE, and
+	 * therefore will not expose the per-thread group members as global.
+	 */
+	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];
+	};
 };
 
 struct perf_evsel {
@@ -58,6 +108,10 @@ struct perf_evsel {
 	u32			 ids;
 	struct perf_evsel	*leader;
 
+	/* For events where the read_format value is per-thread rather than
+	 * global, stores the per-thread cumulative period */
+	struct list_head	per_stream_periods;
+
 	/* parse modifier helper */
 	int			 nr_members;
 	/*
@@ -88,4 +142,9 @@ int perf_evsel__apply_filter(struct perf_evsel *evsel, const char *filter);
 int perf_evsel__alloc_id(struct perf_evsel *evsel, int ncpus, int nthreads);
 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,
+					bool per_thread);
+
 #endif /* __LIBPERF_INTERNAL_EVSEL_H */
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 5596bed1b8c8..fac0557ff6ea 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1474,18 +1474,24 @@ static int deliver_sample_value(struct evlist *evlist,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct sample_read_value *v,
-				struct machine *machine)
+				struct machine *machine,
+				bool per_thread)
 {
 	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, per_thread);
+	}
+
+	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;
 	}
@@ -1506,14 +1512,15 @@ static int deliver_sample_group(struct evlist *evlist,
 				union  perf_event *event,
 				struct perf_sample *sample,
 				struct machine *machine,
-				u64 read_format)
+				u64 read_format,
+				bool per_thread)
 {
 	int ret = -EINVAL;
 	struct sample_read_value *v = sample->read.group.values;
 
 	sample_read_group__for_each(v, sample->read.group.nr, read_format) {
 		ret = deliver_sample_value(evlist, tool, event, sample, v,
-					   machine);
+					   machine, per_thread);
 		if (ret)
 			break;
 	}
@@ -1528,6 +1535,7 @@ static int evlist__deliver_sample(struct evlist *evlist, struct perf_tool *tool,
 	/* We know evsel != NULL. */
 	u64 sample_type = evsel->core.attr.sample_type;
 	u64 read_format = evsel->core.attr.read_format;
+	bool per_thread = perf_evsel__attr_has_per_thread_sample_period(&evsel->core);
 
 	/* Standard sample delivery. */
 	if (!(sample_type & PERF_SAMPLE_READ))
@@ -1536,10 +1544,11 @@ static int evlist__deliver_sample(struct evlist *evlist, struct perf_tool *tool,
 	/* For PERF_SAMPLE_READ we have either single or group mode. */
 	if (read_format & PERF_FORMAT_GROUP)
 		return deliver_sample_group(evlist, tool, event, sample,
-					    machine, read_format);
+					    machine, read_format, per_thread);
 	else
 		return deliver_sample_value(evlist, tool, event, sample,
-					    &sample->read.one, machine);
+					    &sample->read.one, machine,
+					    per_thread);
 }
 
 static int machines__deliver_event(struct machines *machines,
-- 
2.45.2

[PATCH v11 2/2] tools/perf: Allow inherit + PERF_SAMPLE_READ when opening events

[Ben Gainey]

The "perf record" tool will now default to this new mode if the user
specifies a sampling group when not in system-wide mode, and when
"--no-inherit" is not specified.

This change updates evsel to allow the combination of inherit
and PERF_SAMPLE_READ.

A fallback is implemented for kernel versions where this feature is not
supported.

Signed-off-by: Ben Gainey <ben.gainey@arm.com>
---
 tools/perf/tests/attr/README                  |  2 +
 tools/perf/tests/attr/test-record-C0          |  2 +
 tools/perf/tests/attr/test-record-dummy-C0    |  2 +-
 .../tests/attr/test-record-group-sampling     |  3 +-
 .../tests/attr/test-record-group-sampling1    | 51 ++++++++++++++++
 .../tests/attr/test-record-group-sampling2    | 61 +++++++++++++++++++
 tools/perf/tests/attr/test-record-group2      |  1 +
 ...{test-record-group2 => test-record-group3} | 10 +--
 tools/perf/util/evsel.c                       | 21 ++++++-
 tools/perf/util/evsel.h                       |  1 +
 10 files changed, 145 insertions(+), 9 deletions(-)
 create mode 100644 tools/perf/tests/attr/test-record-group-sampling1
 create mode 100644 tools/perf/tests/attr/test-record-group-sampling2
 copy tools/perf/tests/attr/{test-record-group2 => test-record-group3} (81%)

diff --git a/tools/perf/tests/attr/README b/tools/perf/tests/attr/README
index 4066fec7180a..67c4ca76b85d 100644
--- a/tools/perf/tests/attr/README
+++ b/tools/perf/tests/attr/README
@@ -51,6 +51,8 @@ Following tests are defined (with perf commands):
   perf record --call-graph fp kill              (test-record-graph-fp-aarch64)
   perf record -e '{cycles,instructions}' kill   (test-record-group1)
   perf record -e '{cycles/period=1/,instructions/period=2/}:S' kill (test-record-group2)
+  perf record -e '{cycles,cache-misses}:S' kill (test-record-group-sampling1)
+  perf record -c 10000 -e '{cycles,cache-misses}:S' kill (test-record-group-sampling2)
   perf record -D kill                           (test-record-no-delay)
   perf record -i kill                           (test-record-no-inherit)
   perf record -n kill                           (test-record-no-samples)
diff --git a/tools/perf/tests/attr/test-record-C0 b/tools/perf/tests/attr/test-record-C0
index 198e8429a1bf..1049ac8b52f2 100644
--- a/tools/perf/tests/attr/test-record-C0
+++ b/tools/perf/tests/attr/test-record-C0
@@ -18,5 +18,7 @@ sample_type=65927
 mmap=0
 comm=0
 task=0
+inherit=0
 
 [event:system-wide-dummy]
+inherit=0
diff --git a/tools/perf/tests/attr/test-record-dummy-C0 b/tools/perf/tests/attr/test-record-dummy-C0
index 576ec48b3aaf..3050298bd614 100644
--- a/tools/perf/tests/attr/test-record-dummy-C0
+++ b/tools/perf/tests/attr/test-record-dummy-C0
@@ -19,7 +19,7 @@ sample_period=4000
 sample_type=391
 read_format=4|20
 disabled=0
-inherit=1
+inherit=0
 pinned=0
 exclusive=0
 exclude_user=0
diff --git a/tools/perf/tests/attr/test-record-group-sampling b/tools/perf/tests/attr/test-record-group-sampling
index 97e7e64a38f0..86a940d7895d 100644
--- a/tools/perf/tests/attr/test-record-group-sampling
+++ b/tools/perf/tests/attr/test-record-group-sampling
@@ -2,6 +2,7 @@
 command = record
 args    = --no-bpf-event -e '{cycles,cache-misses}:S' kill >/dev/null 2>&1
 ret     = 1
+kernel_until = 6.12
 
 [event-1:base-record]
 fd=1
@@ -18,7 +19,7 @@ group_fd=1
 type=0
 config=3
 
-# default | PERF_SAMPLE_READ
+# default | PERF_SAMPLE_READ | PERF_SAMPLE_PERIOD
 sample_type=343
 
 # PERF_FORMAT_ID | PERF_FORMAT_GROUP  | PERF_FORMAT_LOST
diff --git a/tools/perf/tests/attr/test-record-group-sampling1 b/tools/perf/tests/attr/test-record-group-sampling1
new file mode 100644
index 000000000000..e96a10627a46
--- /dev/null
+++ b/tools/perf/tests/attr/test-record-group-sampling1
@@ -0,0 +1,51 @@
+[config]
+command = record
+args    = --no-bpf-event -e '{cycles,cache-misses}:S' kill >/dev/null 2>&1
+ret     = 1
+kernel_since = 6.12
+
+[event-1:base-record]
+fd=1
+group_fd=-1
+
+# cycles
+type=0
+config=0
+
+# default | PERF_SAMPLE_READ | PERF_SAMPLE_PERIOD
+sample_type=343
+
+# PERF_FORMAT_ID | PERF_FORMAT_GROUP  | PERF_FORMAT_LOST | PERF_FORMAT_TOTAL_TIME_ENABLED | PERF_FORMAT_TOTAL_TIME_RUNNING
+read_format=28|31
+task=1
+mmap=1
+comm=1
+enable_on_exec=1
+disabled=1
+
+# inherit is enabled for group sampling
+inherit=1
+
+[event-2:base-record]
+fd=2
+group_fd=1
+
+# cache-misses
+type=0
+config=3
+
+# default | PERF_SAMPLE_READ | PERF_SAMPLE_PERIOD
+sample_type=343
+
+# PERF_FORMAT_ID | PERF_FORMAT_GROUP  | PERF_FORMAT_LOST | PERF_FORMAT_TOTAL_TIME_ENABLED | PERF_FORMAT_TOTAL_TIME_RUNNING
+read_format=28|31
+task=0
+mmap=0
+comm=0
+enable_on_exec=0
+disabled=0
+freq=0
+
+# inherit is enabled for group sampling
+inherit=1
+
diff --git a/tools/perf/tests/attr/test-record-group-sampling2 b/tools/perf/tests/attr/test-record-group-sampling2
new file mode 100644
index 000000000000..e0432244a0eb
--- /dev/null
+++ b/tools/perf/tests/attr/test-record-group-sampling2
@@ -0,0 +1,61 @@
+[config]
+command = record
+args    = --no-bpf-event -c 10000 -e '{cycles,cache-misses}:S' kill >/dev/null 2>&1
+ret     = 1
+kernel_since = 6.12
+
+[event-1:base-record]
+fd=1
+group_fd=-1
+
+# cycles
+type=0
+config=0
+
+# default | PERF_SAMPLE_READ
+sample_type=87
+
+# PERF_FORMAT_ID | PERF_FORMAT_GROUP  | PERF_FORMAT_LOST | PERF_FORMAT_TOTAL_TIME_ENABLED | PERF_FORMAT_TOTAL_TIME_RUNNING
+read_format=28|31
+task=1
+mmap=1
+comm=1
+enable_on_exec=1
+disabled=1
+
+# inherit is enabled for group sampling
+inherit=1
+
+# sampling disabled
+sample_freq=0
+sample_period=10000
+freq=0
+write_backward=0
+
+[event-2:base-record]
+fd=2
+group_fd=1
+
+# cache-misses
+type=0
+config=3
+
+# default | PERF_SAMPLE_READ
+sample_type=87
+
+# PERF_FORMAT_ID | PERF_FORMAT_GROUP  | PERF_FORMAT_LOST | PERF_FORMAT_TOTAL_TIME_ENABLED | PERF_FORMAT_TOTAL_TIME_RUNNING
+read_format=28|31
+task=0
+mmap=0
+comm=0
+enable_on_exec=0
+disabled=0
+
+# inherit is enabled for group sampling
+inherit=1
+
+# sampling disabled
+sample_freq=0
+sample_period=0
+freq=0
+write_backward=0
diff --git a/tools/perf/tests/attr/test-record-group2 b/tools/perf/tests/attr/test-record-group2
index cebdaa8e64e4..891d41a7bddf 100644
--- a/tools/perf/tests/attr/test-record-group2
+++ b/tools/perf/tests/attr/test-record-group2
@@ -2,6 +2,7 @@
 command = record
 args    = --no-bpf-event -e '{cycles/period=1234000/,instructions/period=6789000/}:S' kill >/dev/null 2>&1
 ret     = 1
+kernel_until = 6.12
 
 [event-1:base-record]
 fd=1
diff --git a/tools/perf/tests/attr/test-record-group2 b/tools/perf/tests/attr/test-record-group3
similarity index 81%
copy from tools/perf/tests/attr/test-record-group2
copy to tools/perf/tests/attr/test-record-group3
index cebdaa8e64e4..249be884959e 100644
--- a/tools/perf/tests/attr/test-record-group2
+++ b/tools/perf/tests/attr/test-record-group3
@@ -2,6 +2,7 @@
 command = record
 args    = --no-bpf-event -e '{cycles/period=1234000/,instructions/period=6789000/}:S' kill >/dev/null 2>&1
 ret     = 1
+kernel_since = 6.12
 
 [event-1:base-record]
 fd=1
@@ -9,8 +10,9 @@ group_fd=-1
 config=0|1
 sample_period=1234000
 sample_type=87
-read_format=12|28
-inherit=0
+read_format=28|31
+disabled=1
+inherit=1
 freq=0
 
 [event-2:base-record]
@@ -19,9 +21,9 @@ group_fd=1
 config=0|1
 sample_period=6789000
 sample_type=87
-read_format=12|28
+read_format=28|31
 disabled=0
-inherit=0
+inherit=1
 mmap=0
 comm=0
 freq=0
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index bc603193c477..d12e1b16313d 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1149,7 +1149,7 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts,
 	bool per_cpu = opts->target.default_per_cpu && !opts->target.per_thread;
 
 	attr->sample_id_all = perf_missing_features.sample_id_all ? 0 : 1;
-	attr->inherit	    = !opts->no_inherit;
+	attr->inherit	    = target__has_cpu(&opts->target) ? 0 : !opts->no_inherit;
 	attr->write_backward = opts->overwrite ? 1 : 0;
 	attr->read_format   = PERF_FORMAT_LOST;
 
@@ -1171,7 +1171,15 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts,
 		 */
 		if (leader->core.nr_members > 1) {
 			attr->read_format |= PERF_FORMAT_GROUP;
-			attr->inherit = 0;
+		}
+
+		/*
+		 * Inherit + SAMPLE_READ requires SAMPLE_TID in the read_format
+		 */
+		if (attr->inherit) {
+			evsel__set_sample_bit(evsel, TID);
+			evsel->core.attr.read_format |=
+				PERF_FORMAT_ID;
 		}
 	}
 
@@ -2020,6 +2028,8 @@ static int __evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
 
 static void evsel__disable_missing_features(struct evsel *evsel)
 {
+	if (perf_missing_features.inherit_sample_read)
+		evsel->core.attr.inherit = 0;
 	if (perf_missing_features.branch_counters)
 		evsel->core.attr.branch_sample_type &= ~PERF_SAMPLE_BRANCH_COUNTERS;
 	if (perf_missing_features.read_lost)
@@ -2075,7 +2085,12 @@ bool evsel__detect_missing_features(struct evsel *evsel)
 	 * Must probe features in the order they were added to the
 	 * perf_event_attr interface.
 	 */
-	if (!perf_missing_features.branch_counters &&
+	if (!perf_missing_features.inherit_sample_read &&
+	    evsel->core.attr.inherit && (evsel->core.attr.sample_type & PERF_SAMPLE_READ)) {
+		perf_missing_features.inherit_sample_read = true;
+		pr_debug2("Using PERF_SAMPLE_READ / :S modifier is not compatible with inherit, falling back to no-inherit.\n");
+		return true;
+	} else if (!perf_missing_features.branch_counters &&
 	    (evsel->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_COUNTERS)) {
 		perf_missing_features.branch_counters = true;
 		pr_debug2("switching off branch counters support\n");
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 80b5f6dd868e..bb0c91c23679 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -206,6 +206,7 @@ struct perf_missing_features {
 	bool weight_struct;
 	bool read_lost;
 	bool branch_counters;
+	bool inherit_sample_read;
 };
 
 extern struct perf_missing_features perf_missing_features;
-- 
2.45.2

Re: [PATCH v11 0/2] tools/perf: Support PERF_SAMPLE_READ with inherit

[Namhyung Kim]

Hello,

On Mon, Aug 05, 2024 at 09:54:56AM +0100, Ben Gainey wrote:
> This revision of this change splits out the tools/perf changes requested 
> by Namhyung Kim for my previous work to enable PERF_SAMPLE READ with inherit (see 
> https://lore.kernel.org/linux-perf-users/20240730084417.7693-1-ben.gainey@arm.com/ ) 
> as the kernel side changes have been picked up by Peter Zijlstra.

Sorry about the long delay.  But unfortunately the current version is
not applied to the current perf-tools-next branch.

Can you please rebase this series?

Thanks,
Namhyung

> 
> Changes since v10:
>  - Fixed a formatting nit
> 
> Changes since v9:
>  - Split out tools/perf patches only
>  - Fixed system-wide mode in `perf record` to not set the inherit bit.
> 
> Changes since v8:
>  - Rebase on v6.11-rc1
> 
> Changes since v7:
>  - Rebase on v6.10-rc3
>  - Respond to Peter Zijlstra's feedback:
>  - Renamed nr_pending to nr_no_switch_fast and merged in nr_inherit_read
>    which otherwise had overlapping use
>  - Updated some of the commit messages to provide better justifications
>    of usecase, behavioural changes and so on
>  - Cleanup perf_event_count/_cumulative
>  - Make it explicit that the sampling event decides whether or not the
>    per-thread value is given in read_format for PERF_RECORD_SAMPLE and
>    PERF_RECORD_READ; updated tools to account for this.
> 
> Changes since v6:
>  - Rebase on v6.10-rc2
>  - Make additional "perf test" tests succeed / skip based on kernel
>    version as per feedback from Namhyung.
> 
> Changes since v5:
>  - Rebase on v6.9
>  - Cleanup feedback from Namhyung Kim
> 
> Changes since v4:
>  - Rebase on v6.9-rc1
>  - Removed the dependency on inherit_stat that was previously assumed
>    necessary as per feedback from Namhyung Kim.
>  - Fixed an incorrect use of zfree instead of free in the tools leading
>    to an abort on tool shutdown.
>  - Additional test coverage improvements added to perf test.
>  - Cleaned up the remaining bit of irrelevant change missed between v3
>    and v4.
> 
> Changes since v3:
>  - Cleaned up perf test data changes incorrectly included into this
>    series from elsewhere.
> 
> Changes since v2:
>  - Rebase on v6.8
>  - Respond to James Clarke's feedback; fixup some typos and move some
>    repeated checks into a helper macro.
>  - Cleaned up checkpatch lints.
>  - Updated perf test; fixed evsel handling so that existing tests pass
>    and added new tests to cover the new behaviour.
> 
> Changes since v1:
>  - Rebase on v6.8-rc1
>  - Fixed value written into sample after child exists.
>  - Modified handling of switch-out so that context with these events
>    take the slow path, so that the per-event/per-thread PMU state is
>    correctly switched.
>  - Modified perf tools to support this mode of operation.
> 
> Ben Gainey (2):
>   tools/perf: Correctly calculate sample period for inherited
>     SAMPLE_READ values
>   tools/perf: Allow inherit + PERF_SAMPLE_READ when opening events
> 
>  tools/lib/perf/evsel.c                        | 48 ++++++++++++++
>  tools/lib/perf/include/internal/evsel.h       | 63 ++++++++++++++++++-
>  tools/perf/tests/attr/README                  |  2 +
>  tools/perf/tests/attr/test-record-C0          |  2 +
>  tools/perf/tests/attr/test-record-dummy-C0    |  2 +-
>  .../tests/attr/test-record-group-sampling     |  3 +-
>  .../tests/attr/test-record-group-sampling1    | 51 +++++++++++++++
>  .../tests/attr/test-record-group-sampling2    | 61 ++++++++++++++++++
>  tools/perf/tests/attr/test-record-group2      |  1 +
>  ...{test-record-group2 => test-record-group3} | 10 +--
>  tools/perf/util/evsel.c                       | 21 ++++++-
>  tools/perf/util/evsel.h                       |  1 +
>  tools/perf/util/session.c                     | 25 +++++---
>  13 files changed, 271 insertions(+), 19 deletions(-)
>  create mode 100644 tools/perf/tests/attr/test-record-group-sampling1
>  create mode 100644 tools/perf/tests/attr/test-record-group-sampling2
>  copy tools/perf/tests/attr/{test-record-group2 => test-record-group3} (81%)
> 
> -- 
> 2.45.2
>