[PATCH v6 33/59] perf check-perf-trace: Port check-perf-trace to use python module

[Ian Rogers]

Add a port of the check-perf-trace script that uses the perf python
module directly. This approach is significantly faster than using perf
script callbacks as it avoids creating intermediate dictionaries for
all event fields.

Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers at google.com>
---
v2:
1. String Match Accuracy: Replaced the substring check for `irq:softirq_entry`
   events with a robust exact string match.

v3:
1. Safe Thread Resolution: Swapped out sample.sample_pid with
   sample.sample_tid and safeguarded the session process lookup with
   a try-except block.

v4:
1. Git Fixup Cleanup: Squashed the lingering fixup commit from the previous
   session into its proper patch.
---
 tools/perf/python/check-perf-trace.py | 113 ++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100755 tools/perf/python/check-perf-trace.py

diff --git a/tools/perf/python/check-perf-trace.py b/tools/perf/python/check-perf-trace.py
new file mode 100755
index 000000000000..7c1c7632a091
--- /dev/null
+++ b/tools/perf/python/check-perf-trace.py
@@ -0,0 +1,113 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+"""
+Basic test of Python scripting support for perf.
+Ported from tools/perf/scripts/python/check-perf-trace.py
+"""
+
+import argparse
+import collections
+import perf
+
+unhandled: collections.defaultdict[str, int] = collections.defaultdict(int)
+session = None
+
+softirq_vecs = {
+    0: "HI_SOFTIRQ",
+    1: "TIMER_SOFTIRQ",
+    2: "NET_TX_SOFTIRQ",
+    3: "NET_RX_SOFTIRQ",
+    4: "BLOCK_SOFTIRQ",
+    5: "IRQ_POLL_SOFTIRQ",
+    6: "TASKLET_SOFTIRQ",
+    7: "SCHED_SOFTIRQ",
+    8: "HRTIMER_SOFTIRQ",
+    9: "RCU_SOFTIRQ",
+}
+
+def trace_begin() -> None:
+    """Called at the start of trace processing."""
+    print("trace_begin")
+
+def trace_end() -> None:
+    """Called at the end of trace processing."""
+    print_unhandled()
+
+def symbol_str(event_name: str, field_name: str, value: int) -> str:
+    """Resolves symbol values to strings."""
+    if event_name == "irq__softirq_entry" and field_name == "vec":
+        return softirq_vecs.get(value, str(value))
+    return str(value)
+
+def flag_str(event_name: str, field_name: str, value: int) -> str:
+    """Resolves flag values to strings."""
+    if event_name == "kmem__kmalloc" and field_name == "gfp_flags":
+        return f"0x{value:x}"
+    return str(value)
+
+def print_header(event_name: str, sample: perf.sample_event) -> None:
+    """Prints common header for events."""
+    secs = sample.sample_time // 1000000000
+    nsecs = sample.sample_time % 1000000000
+    comm = session.find_thread(sample.sample_pid).comm() if session else "[unknown]"
+    print(f"{event_name:<20} {sample.sample_cpu:5} {secs:05}.{nsecs:09} "
+          f"{sample.sample_pid:8} {comm:<20} ", end=' ')
+
+def print_uncommon(sample: perf.sample_event) -> None:
+    """Prints uncommon fields for tracepoints."""
+    # Fallback to 0 if field not found (e.g. on older kernels or if not tracepoint)
+    pc = getattr(sample, "common_preempt_count", 0)
+    flags = getattr(sample, "common_flags", 0)
+    lock_depth = getattr(sample, "common_lock_depth", 0)
+
+    print(f"common_preempt_count={pc}, common_flags={flags}, "
+          f"common_lock_depth={lock_depth}, ")
+
+def irq__softirq_entry(sample: perf.sample_event) -> None:
+    """Handles irq:softirq_entry events."""
+    print_header("irq__softirq_entry", sample)
+    print_uncommon(sample)
+    print(f"vec={symbol_str('irq__softirq_entry', 'vec', sample.vec)}")
+
+def kmem__kmalloc(sample: perf.sample_event) -> None:
+    """Handles kmem:kmalloc events."""
+    print_header("kmem__kmalloc", sample)
+    print_uncommon(sample)
+
+    print(f"call_site={sample.call_site:d}, ptr={sample.ptr:d}, "
+          f"bytes_req={sample.bytes_req:d}, bytes_alloc={sample.bytes_alloc:d}, "
+          f"gfp_flags={flag_str('kmem__kmalloc', 'gfp_flags', sample.gfp_flags)}")
+
+def trace_unhandled(event_name: str) -> None:
+    """Tracks unhandled events."""
+    unhandled[event_name] += 1
+
+def print_unhandled() -> None:
+    """Prints summary of unhandled events."""
+    if not unhandled:
+        return
+    print("\nunhandled events:\n")
+    print(f"{'event':<40} {'count':>10}")
+    print("---------------------------------------- -----------")
+    for event_name, count in unhandled.items():
+        print(f"{event_name:<40} {count:10}")
+
+def process_event(sample: perf.sample_event) -> None:
+    """Callback for processing events."""
+    event_name = str(sample.evsel)
+    if event_name == "evsel(irq:softirq_entry)":
+        irq__softirq_entry(sample)
+    elif "evsel(kmem:kmalloc)" in event_name:
+        kmem__kmalloc(sample)
+    else:
+        trace_unhandled(event_name)
+
+if __name__ == "__main__":
+    ap = argparse.ArgumentParser()
+    ap.add_argument("-i", "--input", default="perf.data", help="Input file name")
+    args = ap.parse_args()
+
+    trace_begin()
+    session = perf.session(perf.data(args.input), sample=process_event)
+    session.process_events()
+    trace_end()
-- 
2.54.0.545.g6539524ca2-goog