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authorSong Liu <songliubraving@fb.com>2019-03-11 22:30:50 -0700
committerArnaldo Carvalho de Melo <acme@redhat.com>2019-03-21 11:27:03 -0300
commit657ee5531903339b06697581532ed32d4762526e (patch)
tree72cf6f621fd22b79d154168245eed807c0e12b83 /tools/perf/builtin-top.c
parent6987561c9e86eace45f2dbb0c564964a63f4150a (diff)
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perf evlist: Introduce side band thread
This patch introduces side band thread that captures extended information for events like PERF_RECORD_BPF_EVENT. This new thread uses its own evlist that uses ring buffer with very low watermark for lower latency. To use side band thread, we need to: 1. add side band event(s) by calling perf_evlist__add_sb_event(); 2. calls perf_evlist__start_sb_thread(); 3. at the end of perf run, perf_evlist__stop_sb_thread(). In the next patch, we use this thread to handle PERF_RECORD_BPF_EVENT. Committer notes: Add fix by Jiri Olsa for when te sb_tread can't get started and then at the end the stop_sb_thread() segfaults when joining the (non-existing) thread. That can happen when running 'perf top' or 'perf record' as a normal user, for instance. Further checks need to be done on top of this to more graciously handle these possible failure scenarios. Signed-off-by: Song Liu <songliubraving@fb.com> Reviewed-by: Jiri Olsa <jolsa@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stanislav Fomichev <sdf@google.com> Link: http://lkml.kernel.org/r/20190312053051.2690567-15-songliubraving@fb.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/builtin-top.c')
-rw-r--r--tools/perf/builtin-top.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index c2ea22c4ea67..3ce8a8db6c1d 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1501,6 +1501,7 @@ int cmd_top(int argc, const char **argv)
"number of thread to run event synthesize"),
OPT_END()
};
+ struct perf_evlist *sb_evlist = NULL;
const char * const top_usage[] = {
"perf top [<options>]",
NULL
@@ -1636,8 +1637,16 @@ int cmd_top(int argc, const char **argv)
goto out_delete_evlist;
}
+ if (perf_evlist__start_sb_thread(sb_evlist, target)) {
+ pr_debug("Couldn't start the BPF side band thread:\nBPF programs starting from now on won't be annotatable\n");
+ opts->no_bpf_event = true;
+ }
+
status = __cmd_top(&top);
+ if (!opts->no_bpf_event)
+ perf_evlist__stop_sb_thread(sb_evlist);
+
out_delete_evlist:
perf_evlist__delete(top.evlist);
perf_session__delete(top.session);