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7f8f56475d
Use the data in bpf-output samples, to assemble off-cpu samples.
In evsel__is_offcpu_event(), check if sample_type is PERF_SAMPLE_RAW to
support off-cpu sample data created by an older version of perf.
Testing compatibility on off-cpu samples collected by perf before this patch series:
See below, the sample_type still uses PERF_SAMPLE_CALLCHAIN
$ perf script --header -i ./perf.data.ptn | grep "event : name = offcpu-time"
# event : name = offcpu-time, , id = { 237917, 237918, 237919, 237920 }, type = 1 (software), size = 136, config = 0xa (PERF_COUNT_SW_BPF_OUTPUT), { sample_period, sample_freq } = 1, sample_type = IP|TID|TIME|CALLCHAIN|CPU|PERIOD|IDENTIFIER, read_format = ID|LOST, disabled = 1, freq = 1, sample_id_all = 1
The output is correct.
$ perf script -i ./perf.data.ptn | grep offcpu-time
gmain 2173 [000] 18446744069.414584: 100102015 offcpu-time:
NetworkManager 901 [000] 18446744069.414584: 5603579 offcpu-time:
Web Content 1183550 [000] 18446744069.414584: 46278 offcpu-time:
gnome-control-c 2200559 [000] 18446744069.414584: 11998247014 offcpu-time:
<SNIP>
$
And after this patch series:
$ perf script --header -i ./perf.data.off-cpu-v9 | grep "event : name = offcpu-time"
# event : name = offcpu-time, , id = { 237959, 237960, 237961, 237962 }, type = 1 (software), size = 136, config = 0xa (PERF_COUNT_SW_BPF_OUTPUT), { sample_period, sample_freq } = 1, sample_type = IP|TID|TIME|CPU|PERIOD|RAW|IDENTIFIER, read_format = ID|LOST, disabled = 1, freq = 1, sample_id_all = 1
$ ./perf script -i ./perf.data.off-cpu-v9 | grep offcpu-time
gnome-shell 1875 [001] 4789616.361225: 100097057 offcpu-time:
gnome-shell 1875 [001] 4789616.461419: 100107463 offcpu-time:
firefox 2206821 [002] 4789616.475690: 255257245 offcpu-time:
$
Committer testing:
The command to record those samples:
root@number:~# perf record --off-cpu -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 2.092 MB perf.data (1552 samples) ]
root@number:~#
Then, before this patch series, the sample_type for the "offcpu-time" event is:
root@number:~# perf evlist -v | grep offcpu-time
offcpu-time: type: 1 (PERF_TYPE_SOFTWARE), size: 136, config: 0xa (PERF_COUNT_SW_BPF_OUTPUT), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CALLCHAIN|CPU|PERIOD|IDENTIFIER, read_format: ID|LOST, disabled: 1, freq: 1, sample_id_all: 1
root@number:~#
And after it, after recording it again:
root@number:~# perf record --off-cpu -a sleep 1 ; perf evlist -v | grep offcpu-time
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 2.151 MB perf.data (2843 samples) ]
offcpu-time: type: 1 (PERF_TYPE_SOFTWARE), size: 136, config: 0xa (PERF_COUNT_SW_BPF_OUTPUT), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CPU|PERIOD|IDENTIFIER, read_format: ID|LOST, disabled: 1, sample_id_all: 1
root@number:~#
Suggested-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Tested-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-7-howardchu95@gmail.com
Link: https://lore.kernel.org/r/20250501022809.449767-6-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.