d37ba88059
Before this patch we can see very large time in the events before the
'bpf-output' event. For example:
# perf trace -vv -T --ev sched:sched_switch \
--ev bpf-output/no-inherit,name=evt/ \
--ev ./test_bpf_trace.c/map:channel.event=evt/ \
usleep 10
...
18446744073709.551 (18446564645918.480 ms): usleep/4157 nanosleep(rqtp: 0x7ffd3f0dc4e0) ...
18446744073709.551 ( ): evt:Raise a BPF event!..)
179427791.076 ( ): perf_bpf_probe:func_begin:(ffffffff810eb9a0))
179427791.081 ( ): sched:sched_switch:usleep:4157 [120] S ==> swapper/2:0 [120])
...
We can also see the differences between bpf-output events and
breakpoint events:
For bpf output event:
sample_type IP|TID|RAW|IDENTIFIER
For tracepoint events:
sample_type IP|TID|TIME|CPU|PERIOD|RAW|IDENTIFIER
This patch fix this differences by adding more sample type for
bpf-output events.
After this patch:
# perf trace -vv -T --ev sched:sched_switch \
--ev bpf-output/no-inherit,name=evt/ \
--ev ./test_bpf_trace.c/map:channel.event=evt/ \
usleep 10
...
179877370.878 ( 0.003 ms): usleep/5336 nanosleep(rqtp: 0x7ffff866c450) ...
179877370.878 ( ): evt:Raise a BPF event!..)
179877370.878 ( ): perf_bpf_probe:func_begin:(ffffffff810eb9a0))
179877370.882 ( ): sched:sched_switch:usleep:5336 [120] S ==> swapper/4:0 [120])
179877370.945 ( ): evt:Raise a BPF event!..)
...
# ./perf trace -vv -T --ev sched:sched_switch \
--ev bpf-output/no-inherit,name=evt/ \
--ev ./test_bpf_trace.c/map:channel.event=evt/ \
usleep 10 2>&1 | grep sample_type
sample_type IP|TID|TIME|ID|CPU|PERIOD|RAW
sample_type IP|TID|TIME|ID|CPU|PERIOD|RAW
sample_type IP|TID|TIME|ID|CPU|PERIOD|RAW
sample_type IP|TID|TIME|ID|CPU|PERIOD|RAW
sample_type IP|TID|TIME|ID|CPU|PERIOD|RAW
sample_type IP|TID|TIME|ID|CPU|PERIOD|RAW
The 'IDENTIFIER' info is not required because all events have the same
sample_type.
Committer notes:
Further testing, on top of the changes making 'perf trace' avoid samples
from events without PERF_SAMPLE_TIME:
Before:
# trace --ev bpf-output/no-inherit,name=evt/ --ev /home/acme/bpf/test_bpf_trace.c/map:channel.event=evt/ usleep 10
<SNIP>
0.560 ( 0.001 ms): brk( ) = 0x55e5a1df8000
18446640227439.430 (18446640227438.859 ms): nanosleep(rqtp: 0x7ffc96643370) ...
18446640227439.430 ( ): evt:Raise a BPF event!..)
0.576 ( ): perf_bpf_probe:func_begin:(ffffffff81112460))
18446640227439.430 ( ): evt:Raise a BPF event!..)
0.645 ( ): perf_bpf_probe:func_end:(ffffffff81112460 <- ffffffff81003d92))
0.646 ( 0.076 ms): ... [continued]: nanosleep()) = 0
#
After:
# trace --ev bpf-output/no-inherit,name=evt/ --ev /home/acme/bpf/test_bpf_trace.c/map:channel.event=evt/ usleep 10
<SNIP>
0.292 ( 0.001 ms): brk( ) = 0x55c7cd6e1000
0.302 ( 0.004 ms): nanosleep(rqtp: 0x7ffedd8bc0f0) ...
0.302 ( ): evt:Raise a BPF event!..)
0.303 ( ): perf_bpf_probe:func_begin:(ffffffff81112460))
0.397 ( ): evt:Raise a BPF event!..)
0.397 ( ): perf_bpf_probe:func_end:(ffffffff81112460 <- ffffffff81003d92))
0.398 ( 0.100 ms): ... [continued]: nanosleep()) = 0
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reported-and-Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1459517202-42320-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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