forked from Minki/linux
384b60557b
LBR call stack only has user-space callchains. It is output in the
PERF_SAMPLE_BRANCH_STACK data format. For kernel callchains, it's
still in the form of PERF_SAMPLE_CALLCHAIN.
The perf tool has to handle both data sources to construct a
complete callstack.
For the "perf report -D" option, both lbr and fp information will be
displayed.
A new call chain recording option "lbr" is introduced into the perf
tool for LBR call stack. The user can use --call-graph lbr to get
the call stack information from hardware.
Here are some examples.
When profiling bc(1) on Fedora 19:
echo 'scale=2000; 4*a(1)' > cmd; perf record --call-graph lbr bc -l < cmd
If enabling LBR, perf report output looks like:
50.36% bc bc [.] bc_divide
|
--- bc_divide
execute
run_code
yyparse
main
__libc_start_main
_start
33.66% bc bc [.] _one_mult
|
--- _one_mult
bc_divide
execute
run_code
yyparse
main
__libc_start_main
_start
7.62% bc bc [.] _bc_do_add
|
--- _bc_do_add
|
|--99.89%-- 0x2000186a8
--0.11%-- [...]
6.83% bc bc [.] _bc_do_sub
|
--- _bc_do_sub
|
|--99.94%-- bc_add
| execute
| run_code
| yyparse
| main
| __libc_start_main
| _start
--0.06%-- [...]
0.46% bc libc-2.17.so [.] __memset_sse2
|
--- __memset_sse2
|
|--54.13%-- bc_new_num
| |
| |--51.00%-- bc_divide
| | execute
| | run_code
| | yyparse
| | main
| | __libc_start_main
| | _start
| |
| |--30.46%-- _bc_do_sub
| | bc_add
| | execute
| | run_code
| | yyparse
| | main
| | __libc_start_main
| | _start
| |
| --18.55%-- _bc_do_add
| bc_add
| execute
| run_code
| yyparse
| main
| __libc_start_main
| _start
|
--45.87%-- bc_divide
execute
run_code
yyparse
main
__libc_start_main
_start
If using FP, perf report output looks like:
echo 'scale=2000; 4*a(1)' > cmd; perf record --call-graph fp bc -l < cmd
50.49% bc bc [.] bc_divide
|
--- bc_divide
33.57% bc bc [.] _one_mult
|
--- _one_mult
7.61% bc bc [.] _bc_do_add
|
--- _bc_do_add
0x2000186a8
6.88% bc bc [.] _bc_do_sub
|
--- _bc_do_sub
0.42% bc libc-2.17.so [.] __memcpy_ssse3_back
|
--- __memcpy_ssse3_back
If using LBR, perf report -D output looks like:
3458145275743 0x2fd750 [0xd8]: PERF_RECORD_SAMPLE(IP, 0x2): 9748/9748: 0x408ea8 period: 609644 addr: 0
... LBR call chain: nr:8
..... 0: fffffffffffffe00
..... 1: 0000000000408e50
..... 2: 000000000040a458
..... 3: 000000000040562e
..... 4: 0000000000408590
..... 5: 00000000004022c0
..... 6: 00000000004015dd
..... 7: 0000003d1cc21b43
... FP chain: nr:2
..... 0: fffffffffffffe00
..... 1: 0000000000408ea8
... thread: bc:9748
...... dso: /usr/bin/bc
The LBR call stack has the following known limitations:
- Zero length calls are not filtered out by the hardware
- Exception handing such as setjmp/longjmp will have calls/returns not
match
- Pushing different return address onto the stack will have
calls/returns not match
- If callstack is deeper than the LBR, only the last entries are
captured
Tested-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Simon Que <sque@chromium.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1420482185-29830-3-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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| .. | ||
| include | ||
| scripting-engines | ||
| abspath.c | ||
| alias.c | ||
| annotate.c | ||
| annotate.h | ||
| bitmap.c | ||
| build-id.c | ||
| build-id.h | ||
| cache.h | ||
| callchain.c | ||
| callchain.h | ||
| cgroup.c | ||
| cgroup.h | ||
| cloexec.c | ||
| cloexec.h | ||
| color.c | ||
| color.h | ||
| comm.c | ||
| comm.h | ||
| config.c | ||
| cpumap.c | ||
| cpumap.h | ||
| ctype.c | ||
| data.c | ||
| data.h | ||
| db-export.c | ||
| db-export.h | ||
| debug.c | ||
| debug.h | ||
| dso.c | ||
| dso.h | ||
| dwarf-aux.c | ||
| dwarf-aux.h | ||
| environment.c | ||
| event.c | ||
| event.h | ||
| evlist.c | ||
| evlist.h | ||
| evsel.c | ||
| evsel.h | ||
| exec_cmd.c | ||
| exec_cmd.h | ||
| find-vdso-map.c | ||
| generate-cmdlist.sh | ||
| header.c | ||
| header.h | ||
| help.c | ||
| help.h | ||
| hist.c | ||
| hist.h | ||
| intlist.c | ||
| intlist.h | ||
| kvm-stat.h | ||
| levenshtein.c | ||
| levenshtein.h | ||
| machine.c | ||
| machine.h | ||
| map.c | ||
| map.h | ||
| ordered-events.c | ||
| ordered-events.h | ||
| pager.c | ||
| parse-events.c | ||
| parse-events.h | ||
| parse-events.l | ||
| parse-events.y | ||
| parse-options.c | ||
| parse-options.h | ||
| path.c | ||
| perf_regs.c | ||
| perf_regs.h | ||
| PERF-VERSION-GEN | ||
| pmu.c | ||
| pmu.h | ||
| pmu.l | ||
| pmu.y | ||
| probe-event.c | ||
| probe-event.h | ||
| probe-finder.c | ||
| probe-finder.h | ||
| pstack.c | ||
| pstack.h | ||
| python-ext-sources | ||
| python.c | ||
| quote.c | ||
| quote.h | ||
| rblist.c | ||
| rblist.h | ||
| record.c | ||
| run-command.c | ||
| run-command.h | ||
| session.c | ||
| session.h | ||
| setup.py | ||
| sigchain.c | ||
| sigchain.h | ||
| sort.c | ||
| sort.h | ||
| srcline.c | ||
| stat.c | ||
| stat.h | ||
| strbuf.c | ||
| strbuf.h | ||
| strfilter.c | ||
| strfilter.h | ||
| string.c | ||
| strlist.c | ||
| strlist.h | ||
| svghelper.c | ||
| svghelper.h | ||
| symbol-elf.c | ||
| symbol-minimal.c | ||
| symbol.c | ||
| symbol.h | ||
| target.c | ||
| target.h | ||
| thread_map.c | ||
| thread_map.h | ||
| thread-stack.c | ||
| thread-stack.h | ||
| thread.c | ||
| thread.h | ||
| tool.h | ||
| top.c | ||
| top.h | ||
| trace-event-info.c | ||
| trace-event-parse.c | ||
| trace-event-read.c | ||
| trace-event-scripting.c | ||
| trace-event.c | ||
| trace-event.h | ||
| tsc.c | ||
| tsc.h | ||
| unwind-libdw.c | ||
| unwind-libdw.h | ||
| unwind-libunwind.c | ||
| unwind.h | ||
| usage.c | ||
| util.c | ||
| util.h | ||
| values.c | ||
| values.h | ||
| vdso.c | ||
| vdso.h | ||
| wrapper.c | ||
| xyarray.c | ||
| xyarray.h | ||
| zlib.c | ||