[PATCH v5 38/58] perf failed-syscalls-by-pid: Port failed-syscalls-by-pid to use python module

Ian Rogers
2026-04-24T16:49:06Z

Ported from tools/perf/scripts/python/failed-syscalls-by-pid.py to use
the perf Python module API.

Key changes:
- Used perf.syscall_name() to resolve syscall names instead of legacy
Util library.
- Used standard collections.defaultdict for nested statistics
aggregation.
- Used errno.errorcode for resolving error strings.
- Supported optional filtering by COMM or PID via command line
arguments.

Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
v2: Fixed Syscall Name Fallback: Handled the case where
perf.syscall_name() returns None , falling back to the string
representation of the syscall ID to avoid TypeError during string
formatting.
---
tools/perf/python/failed-syscalls-by-pid.py | 119 ++++++++++++++++++++
1 file changed, 119 insertions(+)
create mode 100755 tools/perf/python/failed-syscalls-by-pid.py

diff --git a/tools/perf/python/failed-syscalls-by-pid.py b/tools/perf/python/failed-syscalls-by-pid.py
new file mode 100755
index 000000000000..1a8c9bb7e90c
--- /dev/null
+++ b/tools/perf/python/failed-syscalls-by-pid.py
@@ -0,0 +1,119 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+"""
+Displays system-wide failed system call totals, broken down by pid.
+If a [comm] or [pid] arg is specified, only syscalls called by it are displayed.
+
+Ported from tools/perf/scripts/python/failed-syscalls-by-pid.py
+"""
+
+import argparse
+from collections import defaultdict
+import errno
+from typing import Optional
+import perf
+
+
+def strerror(nr: int) -> str:
+ """Return error string for a given errno."""
+ try:
+ return errno.errorcode[abs(nr)]
+ except KeyError:
+ return f"Unknown {nr} errno"
+
+
+class SyscallAnalyzer:
+ """Analyzes failed syscalls and aggregates counts."""
+
+ def __init__(self, for_comm: Optional[str] = None, for_pid: Optional[int] = None):
+ self.for_comm = for_comm
+ self.for_pid = for_pid
+ self.session: Optional[perf.session] = None
+ self.syscalls: dict[tuple[str, int, int, int], int] = defaultdict(int)
+ self.unhandled: dict[str, int] = defaultdict(int)
+
+ def process_event(self, sample: perf.sample_event) -> None:
+ """Process a single sample event."""
+ event_name = str(sample.evsel)
+ if "sys_exit" not in event_name:
+ return
+
+ pid = sample.sample_pid
+ if hasattr(self, 'session') and self.session:
+ comm = self.session.process(pid).comm()
+ else:
+ comm = "Unknown"
+
+ if self.for_comm and comm != self.for_comm:
+ return
+ if self.for_pid and pid != self.for_pid:
+ return
+
+ ret = getattr(sample, "ret", 0)
+ if ret < 0:
+ syscall_id = getattr(sample, "id", -1)
+ if syscall_id == -1:
+ syscall_id = getattr(sample, "sys_id", -1)
+
+ if syscall_id != -1:
+ self.syscalls[(comm, pid, syscall_id, ret)] += 1
+ else:
+ self.unhandled[event_name] += 1
+
+ def print_summary(self) -> None:
+ """Print aggregated statistics."""
+ if self.for_comm is not None:
+ print(f"\nsyscall errors for {self.for_comm}:\n")
+ elif self.for_pid is not None:
+ print(f"\nsyscall errors for PID {self.for_pid}:\n")
+ else:
+ print("\nsyscall errors:\n")
+
+ print(f"{'comm [pid]':<30} {'count':>10}")
+ print(f"{'-' * 30:<30} {'-' * 10:>10}")
+
+ sorted_keys = sorted(self.syscalls.keys(), key=lambda k: (k[0], k[1], k[2]))
+ current_comm_pid = None
+ for comm, pid, syscall_id, ret in sorted_keys:
+ if current_comm_pid != (comm, pid):
+ print(f"\n{comm} [{pid}]")
+ current_comm_pid = (comm, pid)
+ try:
+ name = perf.syscall_name(syscall_id) or str(syscall_id)
+ except AttributeError:
+ name = str(syscall_id)
+ print(f" syscall: {name:<16}")
+ err_str = strerror(ret)
+ count = self.syscalls[(comm, pid, syscall_id, ret)]
+ print(f" err = {err_str:<20} {count:10d}")
+
+
+if __name__ == "__main__":
+ ap = argparse.ArgumentParser(
+ description="Displays system-wide failed system call totals, broken down by pid.")
+ ap.add_argument("-i", "--input", default="perf.data",
+ help="Input file name")
+ ap.add_argument("filter", nargs="?", help="COMM or PID to filter by")
+ args = ap.parse_args()
+
+ F_COMM = None
+ F_PID = None
+
+ if args.filter:
+ try:
+ F_PID = int(args.filter)
+ except ValueError:
+ F_COMM = args.filter
+
+ analyzer = SyscallAnalyzer(F_COMM, F_PID)
+
+ try:
+ print("Press control+C to stop and show the summary")
+ session = perf.session(perf.data(args.input), sample=analyzer.process_event)
+ analyzer.session = session
+ session.process_events()
+ analyzer.print_summary()
+ except KeyboardInterrupt:
+ analyzer.print_summary()
+ except Exception as e:
+ print(f"Error processing events: {e}")
--
2.54.0.545.g6539524ca2-goog