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authorSong Liu <songliubraving@fb.com>2019-03-12 06:30:50 +0100
committerArnaldo Carvalho de Melo <acme@redhat.com>2019-03-21 15:27:03 +0100
commit657ee5531903339b06697581532ed32d4762526e (patch)
tree72cf6f621fd22b79d154168245eed807c0e12b83 /drivers/nfc
parentperf annotate: Enable annotation of BPF programs (diff)
downloadlinux-657ee5531903339b06697581532ed32d4762526e.tar.xz
linux-657ee5531903339b06697581532ed32d4762526e.zip
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>
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