perf: Implement lbr-as-callgraph v2
From: Andi Kleen
Date: Sat Jan 11 2014 - 14:43:14 EST
This patchkit implements lbr-as-callgraphs in per freport,
as an alternative way to present LBR information.
Current perf report does a histogram over the branch edges,
which is useful to look at basic blocks, but doesn't tell
you anything about the larger control flow.
This patchkit adds a new option --branch-history that
adds the branch paths to the callgraph history instead.
This allows to reason about individual branch paths leading
to specific samples.
Updates to v1:
- rebased on perf/core
- fix various issues
- rename the option to --branch-history
- various fixes to display the information more concise
Example output:
% perf record -b -g ./tsrc/tcall
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.044 MB perf.data (~1923 samples) ]
% perf report --branch-history
...
54.91% tcall.c:6 [.] f2 tcall
|
|--66.53%-- f2 tcall.c:5
| |
| |--70.83%-- f1 tcall.c:11
| | f1 tcall.c:10
| | main tcall.c:18
| | main tcall.c:18
| | main tcall.c:17
| | main tcall.c:17
| | f1 tcall.c:13
| | f1 tcall.c:13
| | f2 tcall.c:7
| | f2 tcall.c:5
| | f1 tcall.c:12
| | f1 tcall.c:12
| | f2 tcall.c:7
| | f2 tcall.c:5
| | f1 tcall.c:11
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