[PATCH v2 28/58] perf syscall-counts-by-pid: Port syscall-counts-by-pid to use python module

Ian Rogers
2026-04-23T03:56:37Z

Rewrite tools/perf/scripts/python/syscall-counts-by-pid.py to use the
python module and various style changes. By avoiding the overheads in
the `perf script` execution the performance improves by more than 3.8x
as shown in the following (with PYTHON_PATH and PERF_EXEC_PATH set as
necessary):

```
$ perf record -e raw_syscalls:sys_enter -a sleep 1
...
$ time perf script tools/perf/scripts/python/syscall-counts-by-pid.py perf
Install the python-audit package to get syscall names.
For example:
# apt-get install python3-audit (Ubuntu)
# yum install python3-audit (Fedora)
etc.

Press control+C to stop and show the summary
Warning:
1 out of order events recorded.

syscall events for perf:

comm [pid]/syscalls count
--------------------------------------- ----------

perf [3886080]
1 538989
16 32
203 17
3 2
257 1
204 1
15 1
0 1

perf [3886082]
7 1

real 0m3.852s
user 0m3.512s
sys 0m0.336s
$ time python3 tools/perf/python/syscall-counts-by-pid.py perf
Warning:
1 out of order events recorded.

syscall events for perf:

comm [pid]/syscalls count
--------------------------------------- -----------

perf [3886080]
write 538989
ioctl 32
sched_setaffinity 17
close 2
openat 1
sched_getaffinity 1
rt_sigreturn 1
read 1

perf [3886082]
poll 1

real 0m1.011s
user 0m0.963s
sys 0m0.048s
```

Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
v2:

1. Removed Unused Variable: Removed id_keys which was assigned but
never read.

2. Fallback for Unknown Syscalls: If perf.syscall_name() returns None
for an unmapped ID, it now falls back to the numeric ID string to
prevent TypeError crashes during string formatting.

3. Fallback for Syscall Number Attribute: It now checks for
__syscall_nr first, and if missing, falls back to checking for nr .

4. Robust Process Resolution: Added a try-except block around
session.process(sample.pid).comm() to handle untracked PIDs
gracefully instead of crashing on a TypeError .

5. Restored PID Filtering: The script now attempts to parse the
positional argument as an integer to filter by Process ID. If that
fails, it treats it as a command name (COMM) string to filter by,
restoring behavior from the original legacy script.

6. Support for Custom Input Files: Added a -i / --input command-line
argument to support arbitrarily named trace files, removing the
hardcoded "perf.data" restriction.
---
tools/perf/python/syscall-counts-by-pid.py | 88 ++++++++++++++++++++++
1 file changed, 88 insertions(+)
create mode 100755 tools/perf/python/syscall-counts-by-pid.py

diff --git a/tools/perf/python/syscall-counts-by-pid.py b/tools/perf/python/syscall-counts-by-pid.py
new file mode 100755
index 000000000000..45a98e6e8e01
--- /dev/null
+++ b/tools/perf/python/syscall-counts-by-pid.py
@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+"""
+Displays system-wide system call totals, broken down by syscall.
+If a [comm] arg is specified, only syscalls called by [comm] are displayed.
+"""
+
+import argparse
+from collections import defaultdict
+import perf
+
+syscalls: dict[tuple[str, int, int], int] = defaultdict(int)
+for_comm = None
+for_pid = None
+session = None
+
+
+def print_syscall_totals():
+ """Print aggregated statistics."""
+ if for_comm is not None:
+ print(f"\nsyscall events for {for_comm}:\n")
+ elif for_pid is not None:
+ print(f"\nsyscall events for PID {for_pid}:\n")
+ else:
+ print("\nsyscall events:\n")
+
+ print(f"{'comm [pid]/syscalls':<40} {'count':>10}")
+ print("---------------------------------------- -----------")
+
+ sorted_keys = sorted(syscalls.keys(), key=lambda k: (k[0], k[1], k[2]))
+ current_comm_pid = None
+ for comm, pid, sc_id in sorted_keys:
+ if current_comm_pid != (comm, pid):
+ print(f"\n{comm} [{pid}]")
+ current_comm_pid = (comm, pid)
+ name = perf.syscall_name(sc_id) or str(sc_id)
+ print(f" {name:<38} {syscalls[(comm, pid, sc_id)]:>10}")
+
+
+def process_event(sample):
+ """Process a single sample event."""
+ event_name = str(sample.evsel)
+ if event_name == "evsel(raw_syscalls:sys_enter)":
+ sc_id = getattr(sample, "id", -1)
+ elif event_name.startswith("evsel(syscalls:sys_enter_"):
+ sc_id = getattr(sample, "__syscall_nr", None)
+ if sc_id is None:
+ sc_id = getattr(sample, "nr", -1)
+ else:
+ return
+
+ if sc_id == -1:
+ return
+
+ pid = sample.sample_pid
+
+ if for_pid and pid != for_pid:
+ return
+
+ comm = "unknown"
+ try:
+ if session:
+ proc = session.process(pid)
+ if proc:
+ comm = proc.comm()
+ except (TypeError, AttributeError):
+ pass
+
+ if for_comm and comm != for_comm:
+ return
+ syscalls[(comm, pid, sc_id)] += 1
+
+
+if __name__ == "__main__":
+ ap = argparse.ArgumentParser()
+ ap.add_argument("filter", nargs="?", help="COMM or PID to filter by")
+ ap.add_argument("-i", "--input", default="perf.data", help="Input file name")
+ args = ap.parse_args()
+
+ if args.filter:
+ try:
+ for_pid = int(args.filter)
+ except ValueError:
+ for_comm = args.filter
+
+ session = perf.session(perf.data(args.input), sample=process_event)
+ session.process_events()
+ print_syscall_totals()
--
2.54.0.rc2.533.g4f5dca5207-goog