perf lock: Look up callchain for the contended locks
The lock contention tracepoints don't provide lock names. All we can do is to get stack traces and show the caller instead. To minimize the overhead it's limited to up to 8 stack traces and display the first non-lock function symbol name as a caller. $ perf lock report -F acquired,contended,avg_wait,wait_total Name acquired contended avg wait total wait update_blocked_a... 40 40 3.61 us 144.45 us kernfs_fop_open+... 5 5 3.64 us 18.18 us _nohz_idle_balance 3 3 2.65 us 7.95 us tick_do_update_j... 1 1 6.04 us 6.04 us ep_scan_ready_list 1 1 3.93 us 3.93 us ... Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220615163222.1275500-8-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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