perf report: Add option to enable the LBR stitching approach
With the LBR stitching approach, the reconstructed LBR call stack can
break the HW limitation. However, it may reconstruct invalid call stacks
in some cases, e.g. exception handing such as setjmp/longjmp. Also, it
may impact the processing time especially when the number of samples
with stitched LBRs are huge.
Add an option to enable the approach.
# To display the perf.data header info, please use
# --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 6K of event 'cycles'
# Event count (approx.):
6492797701
#
# Children Self Command Shared Object Symbol
# ........ ........ ............... ..................
# .................................
#
99.99% 99.99% tchain_edit tchain_edit [.] f43
|
---main
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--99.65%--f32
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Committer testing:
$ perf record --call-graph lbr /wb/tchain_edit
[ perf record: Woken up 23 times to write data ]
[ perf record: Captured and wrote 5.578 MB perf.data (6839 samples) ]
$ perf report --header-only | egrep 'cpu(desc|.*capabilities)'
# cpudesc : Intel(R) Core(TM) i5-7500 CPU @ 3.40GHz
# cpu pmu capabilities: branches=32, max_precise=3, pmu_name=skylake
$
Before:
$ perf report --no-children --stdio
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 6K of event 'cycles:u'
# Event count (approx.):
6459523879
#
# Overhead Command Shared Object Symbol
# ........ ........... ................ .......................
#
99.95% tchain_edit tchain_edit [.] f43
|
--99.92%--f43
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0.03% tchain_edit tchain_edit [.] f42
0.01% tchain_edit tchain_edit [.] f41
0.00% tchain_edit tchain_edit [.] f31
0.00% tchain_edit ld-2.29.so [.] _dl_relocate_object
0.00% tchain_edit ld-2.29.so [.] memmove
0.00% tchain_edit [unknown] [k] 0xffffffff93a00b17
After:
$ perf report --stitch-lbr --no-children --stdio
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 6K of event 'cycles:u'
# Event count (approx.):
6459496645
#
# Overhead Command Shared Object Symbol
# ........ ........... ................ ........................
#
99.97% tchain_edit tchain_edit [.] f43
|
--99.93%--f43
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main
__libc_start_main
0.02% tchain_edit [unknown] [k] 0xffffffff93a00b17
0.01% tchain_edit tchain_edit [.] f31
0.00% tchain_edit ld-2.29.so [.] _dl_important_hwcaps
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-14-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
projects / linux-2.6-block.git / commit