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899e5ffbf2
Now we can use it with --overwrite to have a flight recorder mode that
gets snapshot requests from arbitrary events that are processed in the
side band thread together with the PERF_RECORD_BPF_EVENT processing.
Example:
To collect scheduler events until a recvmmsg syscall happens, system
wide:
[root@five a]# rm -f perf.data.2020042717*
[root@five a]# perf record --overwrite -e sched:*switch,syscalls:*recvmmsg --switch-output-event syscalls:sys_enter_recvmmsg
[ perf record: dump data: Woken up 1 times ]
[ perf record: Dump perf.data.2020042717585458 ]
[ perf record: dump data: Woken up 1 times ]
[ perf record: Dump perf.data.2020042717590235 ]
[ perf record: dump data: Woken up 1 times ]
[ perf record: Dump perf.data.2020042717590398 ]
^C[ perf record: Woken up 1 times to write data ]
[ perf record: Dump perf.data.2020042717590511 ]
[ perf record: Captured and wrote 7.244 MB perf.data.<timestamp> ]
So in the above case we had 3 snapshots, the fourth was forced by
control+C:
[root@five a]# ls -la
total 20440
drwxr-xr-x. 2 root root 4096 Apr 27 17:59 .
dr-xr-x---. 12 root root 4096 Apr 27 17:46 ..
-rw-------. 1 root root 3936125 Apr 27 17:58 perf.data.2020042717585458
-rw-------. 1 root root 5074869 Apr 27 17:59 perf.data.2020042717590235
-rw-------. 1 root root 4291037 Apr 27 17:59 perf.data.2020042717590398
-rw-------. 1 root root 7617037 Apr 27 17:59 perf.data.2020042717590511
[root@five a]#
One can make this more precise by adding the switch output event to the
main -e events list, as since this is done asynchronously, a few events
after the signal event will appear in the snapshots, as can be seen
with:
[root@five a]# rm -f perf.data.20200427175*
[root@five a]# perf record --overwrite -e sched:*switch,syscalls:*recvmmsg --switch-output-event syscalls:sys_enter_recvmmsg
[ perf record: dump data: Woken up 1 times ]
[ perf record: Dump perf.data.2020042718024203 ]
[ perf record: dump data: Woken up 1 times ]
[ perf record: Dump perf.data.2020042718024301 ]
[ perf record: dump data: Woken up 1 times ]
[ perf record: Dump perf.data.2020042718024484 ]
^C[ perf record: Woken up 1 times to write data ]
[ perf record: Dump perf.data.2020042718024562 ]
[ perf record: Captured and wrote 7.337 MB perf.data.<timestamp> ]
[root@five a]# perf script -i perf.data.2020042718024203 | tail -15
PacerThread 148586 [005] 122.830729: sched:sched_switch: prev_comm=PacerThread prev_pid=148586...
swapper 0 [000] 122.833588: sched:sched_switch: prev_comm=swapper/0 prev_pid=...
NetworkManager 1251 [000] 122.833619: syscalls:sys_enter_recvmmsg: fd: 0x0000001c, mmsg: 0x7ffe83054a1...
swapper 0 [002] 122.833624: sched:sched_switch: prev_comm=swapper/2 prev_pid=...
swapper 0 [003] 122.833624: sched:sched_switch: prev_comm=swapper/3 prev_pid=...
NetworkManager 1251 [000] 122.833626: syscalls:sys_exit_recvmmsg: 0x1
kworker/3:3-eve 158946 [003] 122.833628: sched:sched_switch: prev_comm=kworker/3:3 prev_pid=15894...
swapper 0 [004] 122.833641: sched:sched_switch: prev_comm=swapper/4 prev_pid=...
NetworkManager 1251 [000] 122.833642: sched:sched_switch: prev_comm=NetworkManage...
perf 228273 [002] 122.833645: sched:sched_switch: prev_comm=perf prev_pid=22827...
swapper 0 [011] 122.833646: sched:sched_switch: prev_comm=swapper/1...
swapper 0 [002] 122.833648: sched:sched_switch: prev_comm=swapper/...
kworker/0:2-eve 207387 [000] 122.833648: sched:sched_switch: prev_comm=kworker/0:2 prev_pid=20738...
kworker/2:3-eve 232038 [002] 122.833652: sched:sched_switch: prev_comm=kworker/2:3 prev_pid=23203...
perf 235825 [003] 122.833653: sched:sched_switch: prev_comm=perf prev_pid=23582...
[root@five a]#
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lore.kernel.org/lkml/20200429131106.27974-8-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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| .. | ||
| accounting | ||
| arch | ||
| bootconfig | ||
| bpf | ||
| build | ||
| cgroup | ||
| debugging | ||
| edid | ||
| firewire | ||
| firmware | ||
| gpio | ||
| hv | ||
| iio | ||
| include | ||
| io_uring | ||
| kvm/kvm_stat | ||
| laptop | ||
| leds | ||
| lib | ||
| memory-model | ||
| nfsd | ||
| objtool | ||
| pci | ||
| pcmcia | ||
| perf | ||
| power | ||
| scripts | ||
| spi | ||
| testing | ||
| thermal/tmon | ||
| time | ||
| usb | ||
| virtio | ||
| vm | ||
| wmi | ||
| Makefile | ||