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Message-ID: <20241108203607.2436749-1-howardchu95@gmail.com>
Date: Fri, 8 Nov 2024 12:36:07 -0800
From: Howard Chu <howardchu95@...il.com>
To: acme@...nel.org
Cc: namhyung@...nel.org,
irogers@...gle.com,
linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org,
Howard Chu <howardchu95@...il.com>
Subject: [PATCH v7 00/10] perf record --off-cpu: Dump off-cpu samples directly
Changes in v7:
- Make off-cpu event system-wide
- Use strtoull instead of strtoul
- Delete unused variable such as sample_id, and sample_type
- Use i as index to update BPF perf_event map
- MAX_OFFCPU_LEN 128 is too big, make it smaller.
- Delete some bound check as it's always guaranteed
- Do not set ip_pos in BPF
- Add a new field for storing stack traces in the tstamp map
- Dump the off-cpu sample directly or save it in the off_cpu map, not both
- Delete the sample_type_off_cpu check
- Use __set_off_cpu_sample() to parse samples instead of a two-pass parsing
Changes in v6:
- Make patches bisectable
Changes in v5:
- Delete unnecessary copy in BPF program
- Remove sample_embed from perf header, hard code off-cpu stuff instead
- Move evsel__is_offcpu_event() to evsel.h
- Minor changes to the test
- Edit some comments
Changes in v4:
- Minimize the size of data output by perf_event_output()
- Keep only one off-cpu event
- Change off-cpu threshold's unit to microseconds
- Set a default off-cpu threshold
- Print the correct error message for the field 'embed' in perf data header
Changes in v3:
- Add off-cpu-thresh argument
- Process direct off-cpu samples in post
Changes in v2:
- Remove unnecessary comments.
- Rename function off_cpu_change_type to off_cpu_prepare_parse
v1:
As mentioned in: https://bugzilla.kernel.org/show_bug.cgi?id=207323
Currently, off-cpu samples are dumped when perf record is exiting. This
results in off-cpu samples being after the regular samples. This patch
series makes possible dumping off-cpu samples on-the-fly, directly into
perf ring buffer. And it dispatches those samples to the correct format
for perf.data consumers.
Before:
```
migration/0 21 [000] 27981.041319: 2944637851 cycles:P: ffffffff90d2e8aa record_times+0xa ([kernel.kallsyms])
perf 770116 [001] 27981.041375: 1 cycles:P: ffffffff90ee4960 event_function+0xf0 ([kernel.kallsyms])
perf 770116 [001] 27981.041377: 1 cycles:P: ffffffff90c184b1 intel_bts_enable_local+0x31 ([kernel.kallsyms])
perf 770116 [001] 27981.041379: 51611 cycles:P: ffffffff91a160b0 native_sched_clock+0x30 ([kernel.kallsyms])
migration/1 26 [001] 27981.041400: 4227682775 cycles:P: ffffffff90d06a74 wakeup_preempt+0x44 ([kernel.kallsyms])
migration/2 32 [002] 27981.041477: 4159401534 cycles:P: ffffffff90d11993 update_load_avg+0x63 ([kernel.kallsyms])
sshd 708098 [000] 18446744069.414584: 286392 offcpu-time:
79a864f1c8bb ppoll+0x4b (/usr/lib/libc.so.6)
585690935cca [unknown] (/usr/bin/sshd)
```
After:
```
perf 774767 [003] 28178.033444: 497 cycles:P: ffffffff91a160c3 native_sched_clock+0x43 ([kernel.kallsyms])
perf 774767 [003] 28178.033445: 399440 cycles:P: ffffffff91c01f8d nmi_restore+0x25 ([kernel.kallsyms])
swapper 0 [001] 28178.036639: 376650973 cycles:P: ffffffff91a1ae99 intel_idle+0x59 ([kernel.kallsyms])
swapper 0 [003] 28178.182921: 348779378 cycles:P: ffffffff91a1ae99 intel_idle+0x59 ([kernel.kallsyms])
blueman-tray 1355 [000] 28178.627906: 100184571 offcpu-time:
7528eef1c39d __poll+0x4d (/usr/lib/libc.so.6)
7528edf7d8fd [unknown] (/usr/lib/libglib-2.0.so.0.8000.2)
7528edf1af95 g_main_context_iteration+0x35 (/usr/lib/libglib-2.0.so.0.8000.2)
7528eda4ab86 g_application_run+0x1f6 (/usr/lib/libgio-2.0.so.0.8000.2)
7528ee6aa596 [unknown] (/usr/lib/libffi.so.8.1.4)
7fff24e862d8 [unknown] ([unknown])
blueman-tray 1355 [000] 28178.728137: 100187539 offcpu-time:
7528eef1c39d __poll+0x4d (/usr/lib/libc.so.6)
7528edf7d8fd [unknown] (/usr/lib/libglib-2.0.so.0.8000.2)
7528edf1af95 g_main_context_iteration+0x35 (/usr/lib/libglib-2.0.so.0.8000.2)
7528eda4ab86 g_application_run+0x1f6 (/usr/lib/libgio-2.0.so.0.8000.2)
7528ee6aa596 [unknown] (/usr/lib/libffi.so.8.1.4)
7fff24e862d8 [unknown] ([unknown])
swapper 0 [000] 28178.463253: 195945410 cycles:P: ffffffff91a1ae99 intel_idle+0x59 ([kernel.kallsyms])
dbus-broker 412 [002] 28178.464855: 376737008 cycles:P: ffffffff91c000a0 entry_SYSCALL_64+0x20 ([kernel.kallsyms])
```
Howard Chu (10):
perf record --off-cpu: Add --off-cpu-thresh option
perf evsel: Expose evsel__is_offcpu_event() for future use
perf record --off-cpu: Parse off-cpu event
perf record --off-cpu: Preparation of off-cpu BPF program
perf record --off-cpu: Dump off-cpu samples in BPF
perf evsel: Assemble offcpu samples
perf record --off-cpu: Disable perf_event's callchain collection
perf script: Display off-cpu samples correctly
perf record --off-cpu: Dump the remaining samples in BPF's stack trace
map
perf test: Add direct off-cpu test
tools/perf/builtin-record.c | 26 ++++++
tools/perf/builtin-script.c | 4 +-
tools/perf/tests/builtin-test.c | 1 +
tools/perf/tests/shell/record_offcpu.sh | 31 ++++++-
tools/perf/tests/tests.h | 1 +
tools/perf/tests/workloads/Build | 1 +
tools/perf/tests/workloads/offcpu.c | 16 ++++
tools/perf/util/bpf_off_cpu.c | 115 ++++++++++++++----------
tools/perf/util/bpf_skel/off_cpu.bpf.c | 85 ++++++++++++++++--
tools/perf/util/evsel.c | 34 ++++++-
tools/perf/util/evsel.h | 2 +
tools/perf/util/off_cpu.h | 3 +-
tools/perf/util/record.h | 1 +
13 files changed, 264 insertions(+), 56 deletions(-)
create mode 100644 tools/perf/tests/workloads/offcpu.c
--
2.43.0
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