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authorChengdong Li <chengdongli@tencent.com>2022-05-17 09:57:26 +0800
committerArnaldo Carvalho de Melo <acme@redhat.com>2022-05-21 14:56:24 -0300
commit51d0bf99b8342be82369aa63eff343bf5df586dd (patch)
tree29d3bb0f0ee5cc177475365bba82a9ceb30dbc36
parent8994e97be3eb3c3a7b59d6223018ffab8c272e2d (diff)
downloadlinux-51d0bf99b8342be82369aa63eff343bf5df586dd.tar.bz2
perf session: Fix Intel LBR callstack entries and nr print message
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>
-rw-r--r--tools/perf/util/session.c26
1 files changed, 21 insertions, 5 deletions
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index f9a320694b85..a7f93f5a1ac8 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1151,9 +1151,20 @@ static void branch_stack__printf(struct perf_sample *sample, bool callstack)
struct branch_entry *entries = perf_sample__branch_entries(sample);
uint64_t i;
- printf("%s: nr:%" PRIu64 "\n",
- !callstack ? "... branch stack" : "... branch callstack",
- sample->branch_stack->nr);
+ if (!callstack) {
+ printf("%s: nr:%" PRIu64 "\n", "... branch stack", sample->branch_stack->nr);
+ } else {
+ /* the reason of adding 1 to nr is because after expanding
+ * branch stack it generates nr + 1 callstack records. e.g.,
+ * B()->C()
+ * A()->B()
+ * the final callstack should be:
+ * C()
+ * B()
+ * A()
+ */
+ printf("%s: nr:%" PRIu64 "\n", "... branch callstack", sample->branch_stack->nr+1);
+ }
for (i = 0; i < sample->branch_stack->nr; i++) {
struct branch_entry *e = &entries[i];
@@ -1169,8 +1180,13 @@ static void branch_stack__printf(struct perf_sample *sample, bool callstack)
(unsigned)e->flags.reserved,
e->flags.type ? branch_type_name(e->flags.type) : "");
} else {
- printf("..... %2"PRIu64": %016" PRIx64 "\n",
- i, i > 0 ? e->from : e->to);
+ if (i == 0) {
+ printf("..... %2"PRIu64": %016" PRIx64 "\n"
+ "..... %2"PRIu64": %016" PRIx64 "\n",
+ i, e->to, i+1, e->from);
+ } else {
+ printf("..... %2"PRIu64": %016" PRIx64 "\n", i+1, e->from);
+ }
}
}
}