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When generating callstack information from branch_stack(Intel LBR), the actual number of callstack entry should be bigger than the number of branch_stack, for example: branch_stack records: B() -> C() A() -> B() converted callstack records should be: C() B() A() though, the number of callstack equals to the number of branch stack plus 1. This patch fixes above issue in branch_stack__printf(). For example, # echo 'scale=2000; 4*a(1)' > cmd # perf record --call-graph lbr bc -l < cmd Before applying this patch, `perf script -D` output: 1220022677386876 0x2a40 [0xd8]: PERF_RECORD_SAMPLE(IP, 0x4002): 17990/17990: 0x40a6d6 period: 894172 addr: 0 ... LBR call chain: nr:8 ..... 0: fffffffffffffe00 ..... 1: 000000000040a410 ..... 2: 000000000040573c ..... 3: 0000000000408650 ..... 4: 00000000004022f2 ..... 5: 00000000004015f5 ..... 6: 00007f5ed6dcb553 ..... 7: 0000000000401698 ... FP chain: nr:2 ..... 0: fffffffffffffe00 ..... 1: 000000000040a6d8 ... branch callstack: nr:6 # which is not consistent with LBR records. ..... 0: 000000000040a410 ..... 1: 0000000000408650 # ditto ..... 2: 00000000004022f2 ..... 3: 00000000004015f5 ..... 4: 00007f5ed6dcb553 ..... 5: 0000000000401698 ... thread: bc:17990 ...... dso: /usr/bin/bc bc 17990 1220022.677386: 894172 cycles: 40a410 [unknown] (/usr/bin/bc) 40573c [unknown] (/usr/bin/bc) 408650 [unknown] (/usr/bin/bc) 4022f2 [unknown] (/usr/bin/bc) 4015f5 [unknown] (/usr/bin/bc) 7f5ed6dcb553 __libc_start_main+0xf3 (/usr/lib64/libc-2.17.so) 401698 [unknown] (/usr/bin/bc) After applied: 1220022677386876 0x2a40 [0xd8]: PERF_RECORD_SAMPLE(IP, 0x4002): 17990/17990: 0x40a6d6 period: 894172 addr: 0 ... LBR call chain: nr:8 ..... 0: fffffffffffffe00 ..... 1: 000000000040a410 ..... 2: 000000000040573c ..... 3: 0000000000408650 ..... 4: 00000000004022f2 ..... 5: 00000000004015f5 ..... 6: 00007f5ed6dcb553 ..... 7: 0000000000401698 ... FP chain: nr:2 ..... 0: fffffffffffffe00 ..... 1: 000000000040a6d8 ... branch callstack: nr:7 ..... 0: 000000000040a410 ..... 1: 000000000040573c ..... 2: 0000000000408650 ..... 3: 00000000004022f2 ..... 4: 00000000004015f5 ..... 5: 00007f5ed6dcb553 ..... 6: 0000000000401698 ... thread: bc:17990 ...... dso: /usr/bin/bc bc 17990 1220022.677386: 894172 cycles: 40a410 [unknown] (/usr/bin/bc) 40573c [unknown] (/usr/bin/bc) 408650 [unknown] (/usr/bin/bc) 4022f2 [unknown] (/usr/bin/bc) 4015f5 [unknown] (/usr/bin/bc) 7f5ed6dcb553 __libc_start_main+0xf3 (/usr/lib64/libc-2.17.so) 401698 [unknown] (/usr/bin/bc) Change from v1: - refined code style according to Jiri's review comments. Signed-off-by: Chengdong Li <chengdongli@tencent.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: German Gomez <german.gomez@arm.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Riccardo Mancini <rickyman7@gmail.com> Cc: likexu@tencent.com Link: https://lore.kernel.org/r/20220517015726.96131-1-chengdongli@tencent.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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| .. | ||
| arch | ||
| bench | ||
| dlfilters | ||
| Documentation | ||
| examples/bpf | ||
| include | ||
| jvmti | ||
| pmu-events | ||
| python | ||
| scripts | ||
| tests | ||
| trace | ||
| ui | ||
| util | ||
| .gitignore | ||
| Build | ||
| builtin-annotate.c | ||
| builtin-bench.c | ||
| builtin-buildid-cache.c | ||
| builtin-buildid-list.c | ||
| builtin-c2c.c | ||
| builtin-config.c | ||
| builtin-daemon.c | ||
| builtin-data.c | ||
| builtin-diff.c | ||
| builtin-evlist.c | ||
| builtin-ftrace.c | ||
| builtin-help.c | ||
| builtin-inject.c | ||
| builtin-kallsyms.c | ||
| builtin-kmem.c | ||
| builtin-kvm.c | ||
| builtin-list.c | ||
| builtin-lock.c | ||
| builtin-mem.c | ||
| builtin-probe.c | ||
| builtin-record.c | ||
| builtin-report.c | ||
| builtin-sched.c | ||
| builtin-script.c | ||
| builtin-stat.c | ||
| builtin-timechart.c | ||
| builtin-top.c | ||
| builtin-trace.c | ||
| builtin-version.c | ||
| builtin.h | ||
| check-headers.sh | ||
| command-list.txt | ||
| CREDITS | ||
| design.txt | ||
| Makefile | ||
| Makefile.config | ||
| Makefile.perf | ||
| MANIFEST | ||
| perf-archive.sh | ||
| perf-completion.sh | ||
| perf-iostat.sh | ||
| perf-read-vdso.c | ||
| perf-sys.h | ||
| perf-with-kcore.sh | ||
| perf.c | ||
| perf.h | ||