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SubjectRe: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling taken at 'callq' instruction
On Wed, Nov 18, 2015 at 03:20:36PM +0800, Wangnan (F) wrote:

SNIP

>
> Then use perf to trace it:
>
> # ./pref record -g -F 9 --call-graph dwarf ./test_dwarf_unwind
> # ./perf report --no-children --stdio
> ...
> 1.23% test_dwarf_unwi test_dwarf_unwind [.] funcc
> |
> ---funcc
> |
> |--0.62%-- funcb
> | funca
> | main
> | __libc_start_main
> | _start
> |
> --0.62%-- 0 <-- I applied Jiri's patch in [1] so see this
> 0,
> which indicates a broken call chain.

can't see this case after multiple running your test,
just the 'end-of-the-callchain' zeros

49.14% test_dwarf_unwi [vdso] [.] __vdso_gettimeofday
|
---__vdso_gettimeofday
funcc
funcb
funca
main
__libc_start_main
_start
0

40.78% test_dwarf_unwi [vdso] [.] 0x0000000000000987
|
---0x7ffe28ab7987
__vdso_gettimeofday
funcc
funcb
funca
main
__libc_start_main
_start
0


what kernel do you have?

jirka


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