CBR events can result in a duplicate branch event, because the state type
defaults to a branch. Fix by clearing the state type.
Example: trace 'sleep' and hope for a frequency change
Before:
$ perf record -e intel_pt//u sleep 0.1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.034 MB perf.data ]
$ perf script --itrace=bpe > before.txt
After:
$ perf script --itrace=bpe > after.txt
$ diff -u before.txt after.txt
--- before.txt 2020-07-07 14:42:18.191508098 +0300
+++ after.txt 2020-07-07 14:42:36.587891753 +0300
@@ -29673,7 +29673,6 @@
sleep 93431 [007] 15411.619905: 1 branches:u:
0 [unknown] ([unknown]) => 7f0818abb2e0
clock_nanosleep@@GLIBC_2.17+0x0 (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
sleep 93431 [007] 15411.619905: 1 branches:u:
7f0818abb30c clock_nanosleep@@GLIBC_2.17+0x2c
(/usr/lib/x86_64-linux-gnu/libc-2.31.so) => 0 [unknown]
([unknown])
sleep 93431 [007] 15411.720069: cbr: cbr: 15 freq: 1507
MHz ( 56%) 7f0818abb30c clock_nanosleep@@GLIBC_2.17+0x2c
(/usr/lib/x86_64-linux-gnu/libc-2.31.so)
- sleep 93431 [007] 15411.720069: 1 branches:u:
7f0818abb30c clock_nanosleep@@GLIBC_2.17+0x2c
(/usr/lib/x86_64-linux-gnu/libc-2.31.so) => 0 [unknown]
([unknown])
sleep 93431 [007] 15411.720076: 1 branches:u:
0 [unknown] ([unknown]) => 7f0818abb30e
clock_nanosleep@@GLIBC_2.17+0x2e (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
sleep 93431 [007] 15411.720077: 1 branches:u:
7f0818abb323 clock_nanosleep@@GLIBC_2.17+0x43
(/usr/lib/x86_64-linux-gnu/libc-2.31.so) => 7f0818ac0eb7 __nanosleep+0x17
(/usr/lib/x86_64-linux-gnu/libc-2.31.so)
sleep 93431 [007] 15411.720077: 1 branches:u:
7f0818ac0ebf __nanosleep+0x1f (/usr/lib/x86_64-linux-gnu/libc-2.31.so) =>
55cb7e4c2827 rpl_nanosleep+0x97 (/usr/bin/sleep)
Signed-off-by: Adrian Hunter <[email protected]>
Fixes: 91de8684f1cff ("perf intel-pt: Cater for CBR change in PSB+")
Fixes: abe5a1d3e4bee ("perf intel-pt: Decoder to output CBR changes
immediately")
Cc: [email protected]
---
tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
index 75c4bd74d521..7ffcbd6fcd1a 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -1977,8 +1977,10 @@ static int intel_pt_walk_trace(struct intel_pt_decoder
*decoder)
* possibility of another CBR change that gets caught up
* in the PSB+.
*/
- if (decoder->cbr != decoder->cbr_seen)
+ if (decoder->cbr != decoder->cbr_seen) {
+ decoder->state.type = 0;
return 0;
+ }
break;
case INTEL_PT_PIP:
@@ -2019,8 +2021,10 @@ static int intel_pt_walk_trace(struct intel_pt_decoder
*decoder)
case INTEL_PT_CBR:
intel_pt_calc_cbr(decoder);
- if (decoder->cbr != decoder->cbr_seen)
+ if (decoder->cbr != decoder->cbr_seen) {
+ decoder->state.type = 0;
return 0;
+ }
break;
case INTEL_PT_MODE_EXEC:
--
2.17.1
