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perf top: Allow filters on events

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Allow filters to be added to perf top events. One use is to workaround
issues with:
```
$ perf top --uid="$(id -u)"
```
which tries to scan /proc find processes belonging to the uid and can
fail in such a pid terminates between the scan and the
perf_event_open reporting:
```
Error:
The sys_perf_event_open() syscall returned with 3 (No such process) for event (cycles:P).
/bin/dmesg | grep -i perf may provide additional information.
```
A similar filter:
```
$ perf top -e cycles:P --filter "uid == $(id -u)"
```
doesn't fail this way.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240524205227.244375-4-irogers@google.com
This commit is contained in:
Ian Rogers 2024-05-24 13:52:27 -07:00 committed by Namhyung Kim
parent d92aa899fe
commit af75201634
2 changed files with 13 additions and 0 deletions
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4
tools/perf/Documentation/perf-top.txt
View File

@ -43,6 +43,10 @@ Default is to monitor all CPUS.
encoding with the layout of the event control registers as described
by entries in /sys/bus/event_source/devices/cpu/format/*.
--filter=<filter>::
Event filter. This option should follow an event selector (-e). For
syntax see linkperf:perf-record[1].
-E <entries>::
--entries=<entries>::
Display this many functions.

9
tools/perf/builtin-top.c
View File

@ -1055,6 +1055,13 @@ try_again:
}
}
if (evlist__apply_filters(evlist, &counter)) {
pr_err("failed to set filter \"%s\" on event %s with %d (%s)\n",
counter->filter ?: "BPF", evsel__name(counter), errno,
str_error_r(errno, msg, sizeof(msg)));
goto out_err;
}
if (evlist__mmap(evlist, opts->mmap_pages) < 0) {
ui__error("Failed to mmap with %d (%s)\n",
errno, str_error_r(errno, msg, sizeof(msg)));
@ -1462,6 +1469,8 @@ int cmd_top(int argc, const char **argv)
OPT_CALLBACK('e', "event", &parse_events_option_args, "event",
"event selector. use 'perf list' to list available events",
parse_events_option),
OPT_CALLBACK(0, "filter", &top.evlist, "filter",
"event filter", parse_filter),
OPT_U64('c', "count", &opts->user_interval, "event period to sample"),
OPT_STRING('p', "pid", &target->pid, "pid",
"profile events on existing process id"),