6.16-stable review patch. If anyone has any objections, please let me know.
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From: Ian Rogers irogers@google.com
[ Upstream commit 6183afcba9c1c810656ddb36170106aaf3cf778c ]
Tool PMUs assume that stat's process_counter_values is being used to read the counters. Specifically they hold onto old values in evsel->prev_raw_counts and give the cumulative count based off of this value. Update pyrf_evsel__read to allocate counts and prev_raw_counts, use evsel__read_counter rather than perf_evsel__read so tool PMUs are read from not just perf_event_open events, make the returned pyrf_counts_values contain the delta value rather than the cumulative value.
Fixes: 739621f65702 ("perf python: Add evsel read method") Signed-off-by: Ian Rogers irogers@google.com Link: https://lore.kernel.org/r/20250710235126.1086011-12-irogers@google.com Signed-off-by: Namhyung Kim namhyung@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/python.c | 47 +++++++++++++++++++++++++++++++++++++--- 1 file changed, 44 insertions(+), 3 deletions(-)
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c index eb560e3f9e35..b9fe7f2c14af 100644 --- a/tools/perf/util/python.c +++ b/tools/perf/util/python.c @@ -10,6 +10,7 @@ #endif #include <perf/mmap.h> #include "callchain.h" +#include "counts.h" #include "evlist.h" #include "evsel.h" #include "event.h" @@ -888,12 +889,38 @@ static PyObject *pyrf_evsel__threads(struct pyrf_evsel *pevsel) return (PyObject *)pthread_map; }
+/* + * Ensure evsel's counts and prev_raw_counts are allocated, the latter + * used by tool PMUs to compute the cumulative count as expected by + * stat's process_counter_values. + */ +static int evsel__ensure_counts(struct evsel *evsel) +{ + int nthreads, ncpus; + + if (evsel->counts != NULL) + return 0; + + nthreads = perf_thread_map__nr(evsel->core.threads); + ncpus = perf_cpu_map__nr(evsel->core.cpus); + + evsel->counts = perf_counts__new(ncpus, nthreads); + if (evsel->counts == NULL) + return -ENOMEM; + + evsel->prev_raw_counts = perf_counts__new(ncpus, nthreads); + if (evsel->prev_raw_counts == NULL) + return -ENOMEM; + + return 0; +} + static PyObject *pyrf_evsel__read(struct pyrf_evsel *pevsel, PyObject *args, PyObject *kwargs) { struct evsel *evsel = &pevsel->evsel; int cpu = 0, cpu_idx, thread = 0, thread_idx; - struct perf_counts_values counts; + struct perf_counts_values *old_count, *new_count; struct pyrf_counts_values *count_values = PyObject_New(struct pyrf_counts_values, &pyrf_counts_values__type);
@@ -914,8 +941,22 @@ static PyObject *pyrf_evsel__read(struct pyrf_evsel *pevsel, thread); return NULL; } - perf_evsel__read(&(evsel->core), cpu_idx, thread_idx, &counts); - count_values->values = counts; + + if (evsel__ensure_counts(evsel)) + return PyErr_NoMemory(); + + /* Set up pointers to the old and newly read counter values. */ + old_count = perf_counts(evsel->prev_raw_counts, cpu_idx, thread_idx); + new_count = perf_counts(evsel->counts, cpu_idx, thread_idx); + /* Update the value in evsel->counts. */ + evsel__read_counter(evsel, cpu_idx, thread_idx); + /* Copy the value and turn it into the delta from old_count. */ + count_values->values = *new_count; + count_values->values.val -= old_count->val; + count_values->values.ena -= old_count->ena; + count_values->values.run -= old_count->run; + /* Save the new count over the old_count for the next read. */ + *old_count = *new_count; return (PyObject *)count_values; }