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Message-Id: <20220509114743.22668-1-chengdongli@tencent.com>
Date: Mon, 9 May 2022 19:47:43 +0800
From: Chengdong Li <brytonlee01@...il.com>
To: alexey.v.bayduraev@...ux.intel.com, peterz@...radead.org,
mingo@...hat.com, acme@...nel.org, mark.rutland@....com,
alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
namhyung@...nel.org, rickyman7@...il.com, adrian.hunter@...el.com,
irogers@...gle.com, german.gomez@....com,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: ak@...ux.intel.com, likexu@...cent.com, chengdongli@...cent.com
Subject: [PATCH] perf tools: fix callstack entries and nr print message
From: Chengdong Li <chengdongli@...cent.com>
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 fix 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)
Signed-off-by: Chengdong Li <chengdongli@...cent.com>
---
tools/perf/util/session.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index f9a320694b85..568a1db98686 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1151,9 +1151,19 @@ 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 +1179,12 @@ 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);
}
}
}
--
2.27.0
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