[PATCH 37/57] perf trace: Honour --max-events in processing syscalls:sys_enter_*

Arnaldo Carvalho de Melo
2019-10-21T13:42:22Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

We were doing this only at the sys_exit syscall tracepoint, as for
strace-like we count the pair of sys_enter and sys_exit as one event,
but when asking specifically for a the syscalls:sys_enter_NAME
tracepoint we need to count each of those as an event.

I.e. things like:

# perf trace --max-events=4 -e syscalls:sys_enter_lseek
0.000 pool/2242 syscalls:sys_enter_lseek(fd: 14<anon_inode:[timerfd]>, offset: 0, whence: CUR)
0.034 pool/2242 syscalls:sys_enter_lseek(fd: 15<anon_inode:[timerfd]>, offset: 0, whence: CUR)
0.051 pool/2242 syscalls:sys_enter_lseek(fd: 16<anon_inode:[timerfd]>, offset: 0, whence: CUR)
2307.900 sshd/30800 syscalls:sys_enter_lseek(fd: 3</usr/lib64/libsystemd.so.0.25.0>, offset: 9032, whence: SET)
#

Were going on forever, since we only had sys_enter events.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-0ob1dky1a9ijlfrfhxyl40wr@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-trace.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 0294b17ed510..1aaf7b28eec4 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -2727,12 +2727,6 @@ static int trace__event_handler(struct trace *trace, struct evsel *evsel,
} else {
trace__fprintf_tp_fields(trace, evsel, sample, thread, NULL, 0);
}
- ++trace->nr_events_printed;
-
- if (evsel->max_events != ULONG_MAX && ++evsel->nr_events_printed == evsel->max_events) {
- evsel__disable(evsel);
- evsel__close(evsel);
- }
}
}

@@ -2743,6 +2737,13 @@ static int trace__event_handler(struct trace *trace, struct evsel *evsel,
trace__fprintf_callchain(trace, sample);
else if (callchain_ret < 0)
pr_err("Problem processing %s callchain, skipping...\n", perf_evsel__name(evsel));
+
+ ++trace->nr_events_printed;
+
+ if (evsel->max_events != ULONG_MAX && ++evsel->nr_events_printed == evsel->max_events) {
+ evsel__disable(evsel);
+ evsel__close(evsel);
+ }
out:
thread__put(thread);
return 0;
--
2.21.0