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Date: Thu, 20 Oct 2022 18:25:09 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Jiri Olsa <jolsa@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org
Subject: [PATCH] perf scripts python: intel-pt-events.py: Add ability interleave output
Intel PT timestamps are not provided for every branch, let alone every
instruction, so there can be many samples with the same timestamp. With
per-cpu contexts, decoding is done for each CPU in turn, which can make it
difficult to see what is happening on different CPUs at the same time.
Currently the interleaving from perf script --itrace=i0ns is quite coarse
grained. There are often long stretches executing on one CPU and nothing on
another.
Some people are interested in seeing what happened on multiple CPUs before
a crash to debug races etc.
To improve perf script interleaving for parallel execution, the
intel-pt-events.py script has been enhanced to enable interleaving the
output with the same timestamp from different CPUs. It is understood that
interleaving is not perfect or causal.
Add parameter --interleave [<n>] to interleave sample output for the same
timestamp so that no more than n samples for a CPU are displayed in a row.
'n' defaults to 4. Note this only affects the order of output, and only
when the timestamp is the same.
Example:
$ perf script intel-pt-events.py --insn-trace --interleave 3
...
bash 2267/2267 [004] 9323.692625625 563caa3c86f0 jz 0x563caa3c89c7 run_pending_traps+0x30 (/usr/bin/bash) IPC: 1.52 (38/25)
bash 2267/2267 [004] 9323.692625625 563caa3c89c7 movq 0x118(%rsp), %rax run_pending_traps+0x307 (/usr/bin/bash)
bash 2267/2267 [004] 9323.692625625 563caa3c89cf subq %fs:0x28, %rax run_pending_traps+0x30f (/usr/bin/bash)
bash 2270/2270 [007] 9323.692625625 55dc58cabf02 jz 0x55dc58cabf48 unquoted_glob_pattern_p+0x102 (/usr/bin/bash) IPC: 1.56 (25/16)
bash 2270/2270 [007] 9323.692625625 55dc58cabf04 cmp $0x5d, %al unquoted_glob_pattern_p+0x104 (/usr/bin/bash)
bash 2270/2270 [007] 9323.692625625 55dc58cabf06 jnz 0x55dc58cabf10 unquoted_glob_pattern_p+0x106 (/usr/bin/bash)
bash 2264/2264 [001] 9323.692625625 7fd556a4376c jbe 0x7fd556a43ac8 round_and_return+0x3fc (/usr/lib/x86_64-linux-gnu/libc.so.6) IPC: 4.30 (43/10)
bash 2264/2264 [001] 9323.692625625 7fd556a43772 and $0x8, %edx round_and_return+0x402 (/usr/lib/x86_64-linux-gnu/libc.so.6)
bash 2264/2264 [001] 9323.692625625 7fd556a43775 jnz 0x7fd556a43ac8 round_and_return+0x405 (/usr/lib/x86_64-linux-gnu/libc.so.6)
bash 2267/2267 [004] 9323.692625625 563caa3c89d8 jnz 0x563caa3c8b11 run_pending_traps+0x318 (/usr/bin/bash)
bash 2267/2267 [004] 9323.692625625 563caa3c89de add $0x128, %rsp run_pending_traps+0x31e (/usr/bin/bash)
bash 2267/2267 [004] 9323.692625625 563caa3c89e5 popq %rbx run_pending_traps+0x325 (/usr/bin/bash)
...
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
tools/perf/Documentation/perf-intel-pt.txt | 12 +++-
tools/perf/scripts/python/intel-pt-events.py | 65 +++++++++++++++++++-
2 files changed, 74 insertions(+), 3 deletions(-)
diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index 92464a5d7eaf..7b6ccd2fa3bf 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -189,8 +189,16 @@ There is also script intel-pt-events.py which provides an example of how to
unpack the raw data for power events and PTWRITE. The script also displays
branches, and supports 2 additional modes selected by option:
- --insn-trace - instruction trace
- --src-trace - source trace
+ - --insn-trace - instruction trace
+ - --src-trace - source trace
+
+The intel-pt-events.py script also has options:
+
+ - --all-switch-events - display all switch events, not only the last consecutive.
+ - --interleave [<n>] - interleave sample output for the same timestamp so that
+ no more than n samples for a CPU are displayed in a row. 'n' defaults to 4.
+ Note this only affects the order of output, and only when the timestamp is the
+ same.
As mentioned above, it is easy to capture too much data. One way to limit the
data captured is to use 'snapshot' mode which is explained further below.
diff --git a/tools/perf/scripts/python/intel-pt-events.py b/tools/perf/scripts/python/intel-pt-events.py
index 6be7fd8fd615..08862a2582f4 100644
--- a/tools/perf/scripts/python/intel-pt-events.py
+++ b/tools/perf/scripts/python/intel-pt-events.py
@@ -13,10 +13,12 @@
from __future__ import print_function
+import io
import os
import sys
import struct
import argparse
+import contextlib
from libxed import LibXED
from ctypes import create_string_buffer, addressof
@@ -39,6 +41,11 @@ glb_src = False
glb_source_file_name = None
glb_line_number = None
glb_dso = None
+glb_stash_dict = {}
+glb_output = None
+glb_output_pos = 0
+glb_cpu = -1
+glb_time = 0
def get_optional_null(perf_dict, field):
if field in perf_dict:
@@ -70,6 +77,7 @@ def trace_begin():
ap.add_argument("--insn-trace", action='store_true')
ap.add_argument("--src-trace", action='store_true')
ap.add_argument("--all-switch-events", action='store_true')
+ ap.add_argument("--interleave", type=int, nargs='?', const=4, default=0)
global glb_args
global glb_insn
global glb_src
@@ -94,11 +102,39 @@ def trace_begin():
perf_set_itrace_options(perf_script_context, itrace)
def trace_end():
+ if glb_args.interleave:
+ flush_stashed_output()
print("End")
def trace_unhandled(event_name, context, event_fields_dict):
print(' '.join(['%s=%s'%(k,str(v))for k,v in sorted(event_fields_dict.items())]))
+def stash_output():
+ global glb_stash_dict
+ global glb_output_pos
+ output_str = glb_output.getvalue()[glb_output_pos:]
+ n = len(output_str)
+ if n:
+ glb_output_pos += n
+ if glb_cpu not in glb_stash_dict:
+ glb_stash_dict[glb_cpu] = []
+ glb_stash_dict[glb_cpu].append(output_str)
+
+def flush_stashed_output():
+ global glb_stash_dict
+ while glb_stash_dict:
+ cpus = list(glb_stash_dict.keys())
+ # Output at most glb_args.interleave output strings per cpu
+ for cpu in cpus:
+ items = glb_stash_dict[cpu]
+ countdown = glb_args.interleave
+ while len(items) and countdown:
+ sys.stdout.write(items[0])
+ del items[0]
+ countdown -= 1
+ if not items:
+ del glb_stash_dict[cpu]
+
def print_ptwrite(raw_buf):
data = struct.unpack_from("<IQ", raw_buf)
flags = data[0]
@@ -375,15 +411,40 @@ def do_process_event(param_dict):
print_common_start(comm, sample, name)
print_common_ip(param_dict, sample, symbol, dso)
+def interleave_events(param_dict):
+ global glb_cpu
+ global glb_time
+ global glb_output
+ global glb_output_pos
+
+ sample = param_dict["sample"]
+ glb_cpu = sample["cpu"]
+ ts = sample["time"]
+
+ if glb_time != ts:
+ glb_time = ts
+ flush_stashed_output()
+
+ glb_output_pos = 0
+ with contextlib.redirect_stdout(io.StringIO()) as glb_output:
+ do_process_event(param_dict)
+
+ stash_output()
+
def process_event(param_dict):
try:
- do_process_event(param_dict)
+ if glb_args.interleave:
+ interleave_events(param_dict)
+ else:
+ do_process_event(param_dict)
except broken_pipe_exception:
# Stop python printing broken pipe errors and traceback
sys.stdout = open(os.devnull, 'w')
sys.exit(1)
def auxtrace_error(typ, code, cpu, pid, tid, ip, ts, msg, cpumode, *x):
+ if glb_args.interleave:
+ flush_stashed_output()
if len(x) >= 2 and x[0]:
machine_pid = x[0]
vcpu = x[1]
@@ -403,6 +464,8 @@ def auxtrace_error(typ, code, cpu, pid, tid, ip, ts, msg, cpumode, *x):
sys.exit(1)
def context_switch(ts, cpu, pid, tid, np_pid, np_tid, machine_pid, out, out_preempt, *x):
+ if glb_args.interleave:
+ flush_stashed_output()
if out:
out_str = "Switch out "
else:
--
2.34.1
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