Re: [PATCH 0/1] perf report: append inlines to non-dwarf callchains

[Artem Savkov]

On Thu, Mar 16, 2023 at 02:26:18PM -0700, Namhyung Kim wrote:
> Hello,
> 
> On Thu, Mar 16, 2023 at 6:36 AM Artem Savkov <asavkov@xxxxxxxxxx> wrote:
> >
> > In an email to Arnaldo Andrii Nakryiko suggested that perf can get
> > information about inlined functions from dwarf when available and then
> > add it to userspace stacktraces even in framepointer or lbr mode.
> > Looking closer at perf it turned out all required bits and pieces are
> > already there and inline information can be easily added to both
> > framepointer and lbr callchains by adding an append_inlines() call to
> > add_callchain_ip().
> 
> Looks great!  Have you checked it with perf report -g callee ?
> I'm not sure the ordering of inlined functions is maintained
> properly.  Maybe you can use --no-children too to simplify
> the output.

Thanks for the suggestion. I actually have another test program with
functions being numbered rather than (creatively) named, so it might be
easier to use it to figure out ordering. Here's the code:

======
#include <stdio.h>
#include <stdint.h>

static __attribute__((noinline)) uint32_t func5(uint32_t i)
{
        return i + 10;
}

static uint32_t func4(uint32_t i)
{
        return func5(i + 5);
}

static inline uint32_t func3(uint32_t i)
{
        return func4(i + 4);
}

static __attribute__((noinline)) uint32_t func2(uint32_t i)
{
        return func3(i + 3);
}

static uint32_t func1(uint32_t i)
{
        return func2(i + 2);
}

__attribute__((noinline)) uint64_t entry(void)
{
        uint64_t ret = 0;
        uint32_t i = 0;
        for (i = 0; i < 1000000; i++) {
                ret += func1(i);
                ret -= func2(i);
                ret += func3(i);
                ret += func4(i);
                ret -= func5(i);
        }
        return ret;
}

int main(int argc, char **argv)
{
        printf("%s\n", __func__);
        return entry();
}
======

Here is the output I get with '--call-graph callee --no-children'
======
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 250  of event 'cycles:u'
# Event count (approx.): 26819859
#
# Overhead  Command  Shared Object         Symbol                               
# ........  .......  ....................  .....................................
#
    43.58%  a.out    a.out                 [.] func5
            |          
            |--28.93%--entry
            |          main
            |          __libc_start_call_main
            |          
             --14.65%--func4 (inlined)
                       |          
                       |--10.45%--entry
                       |          main
                       |          __libc_start_call_main
                       |          
                        --4.20%--func3 (inlined)
                                  entry
                                  main
                                  __libc_start_call_main

    38.80%  a.out    a.out                 [.] entry
            |          
            |--23.27%--func4 (inlined)
            |          |          
            |          |--20.28%--func3 (inlined)
            |          |          func2
            |          |          main
            |          |          __libc_start_call_main
            |          |          
            |           --2.99%--entry
            |                     main
            |                     __libc_start_call_main
            |          
            |--8.17%--func5
            |          main
            |          __libc_start_call_main
            |          
            |--3.89%--func1 (inlined)
            |          entry
            |          main
            |          __libc_start_call_main
            |          
             --3.48%--entry
                       main
                       __libc_start_call_main

    13.07%  a.out    a.out                 [.] func2
            |
            ---func5
               main
               __libc_start_call_main

     1.54%  a.out    [unknown]             [k] 0xffffffff81e011b7
     1.16%  a.out    [unknown]             [k] 0xffffffff81e00193
            |          
             --0.57%--__mmap64 (inlined)
                       __mmap64 (inlined)

     0.34%  a.out    ld-linux-x86-64.so.2  [.] __tunable_get_val
     0.34%  a.out    ld-linux-x86-64.so.2  [.] strcmp
     0.32%  a.out    libc.so.6             [.] strchr
     0.31%  a.out    ld-linux-x86-64.so.2  [.] _dl_relocate_object
     0.22%  a.out    ld-linux-x86-64.so.2  [.] _dl_init_paths
     0.18%  a.out    ld-linux-x86-64.so.2  [.] get_common_cache_info.constprop.0
     0.14%  a.out    ld-linux-x86-64.so.2  [.] __GI___tunables_init


#
# (Tip: Show individual samples with: perf script)
#
======

It does not seem to be out of order, or at least it is consistent with
what I get with dwarf unwinders.

> 
> Thanks,
> Namhyung
> 
> >
> > I used the following small program for testing:
> >
> > ======
> > #include <stdio.h>
> > #include <stdint.h>
> >
> > static __attribute__((noinline)) uint32_t func_noinline2(uint32_t i)
> > {
> >         return i + 10;
> > }
> >
> > static inline uint32_t func_declared_inlined(uint32_t i)
> > {
> >         return func_noinline2(i + 4);
> > }
> >
> > static __attribute__((noinline)) uint32_t func_noinline(uint32_t i)
> > {
> >         return func_declared_inlined(i + 3);
> > }
> >
> > static uint32_t func_inlined(uint32_t i)
> > {
> >         return func_noinline(i + 2);
> > }
> >
> > int main(int argc, char **argv)
> > {
> >         uint64_t ret = 0;
> >         uint32_t i = 0;
> >
> >         for (i = 0; i < 10000000; i++) {
> >                 ret += func_inlined(i);
> >                 ret -= func_noinline(i);
> >                 ret -= func_noinline2(i);
> >                 ret += func_declared_inlined(i);
> >         }
> >
> >         printf("%s: %ld\n", __func__, ret);
> >         return ret;
> > }
> > ======
> >
> > When built with "gcc -Wall -fno-omit-frame-pointer -O2 -g" (gcc
> > version 12.2.1 20221121 (Red Hat 12.2.1-4) (GCC)) it results in
> > func_inlined() and func_declared_inlined() being inlined into main()
> > and func_declared_inlined() also being inlined into func_noinline().
> >
> > Here are the diffs for 'perf report --call-graph --stdio' output before
> > and after the patch:
> >
> > Frame-pointer mode recorded with 'perf record --call-graph=fp --freq=max -- ./a.out'
> > ======
> > --- unpatched.fp        2023-03-16 13:27:22.724017900 +0100
> > +++ patched.fp  2023-03-16 13:27:28.608857921 +0100
> > @@ -14,18 +14,24 @@
> >              ---__libc_start_call_main
> >                 |
> >                 |--46.31%--main
> > +               |          |
> > +               |           --11.16%--func_declared_inlined (inlined)
> >                 |
> >                 |--27.41%--func_noinline
> > +               |          func_declared_inlined (inlined)
> >                 |
> >                  --25.68%--func_noinline2
> >
> >      85.71%    39.64%  a.out    a.out                 [.] main
> >              |
> >              |--46.07%--main
> > +            |          |
> > +            |           --11.16%--func_declared_inlined (inlined)
> >              |
> >               --39.64%--__libc_start_call_main
> >                         |
> >                         |--27.17%--func_noinline
> > +                       |          func_declared_inlined (inlined)
> >                         |
> >                          --12.23%--func_noinline2
> >
> > @@ -34,31 +40,47 @@
> >              |--46.31%--__libc_start_call_main
> >              |          |
> >              |           --46.07%--main
> > +            |                     |
> > +            |                      --11.16%--func_declared_inlined (inlined)
> >              |
> >               --25.44%--func_noinline2
> >
> >      40.56%    13.39%  a.out    a.out                 [.] func_noinline
> >              |
> >              |--27.17%--func_noinline
> > +            |          func_declared_inlined (inlined)
> >              |
> >               --13.39%--__libc_start_call_main
> >                         |
> >                          --13.15%--func_noinline2
> >
> > +    27.41%     0.00%  a.out    a.out                 [.] func_declared_inlined (inlined)
> > +            |
> > +            ---func_declared_inlined (inlined)
> > +
> > +    11.16%     0.00%  a.out    a.out                 [.] func_declared_inlined (inlined)
> > +            |
> > +            ---func_declared_inlined (inlined)
> > +
> >       0.30%     0.30%  a.out    [unknown]             [k] 0xffffffff81e011b7
> >       0.27%     0.00%  a.out    ld-linux-x86-64.so.2  [.] _dl_start_user
> >       0.25%     0.00%  a.out    ld-linux-x86-64.so.2  [.] _dl_sysdep_start
> >       0.20%     0.00%  a.out    ld-linux-x86-64.so.2  [.] dl_main
> >       0.19%     0.19%  a.out    [unknown]             [k] 0xffffffff81e00193
> > +     0.18%     0.00%  a.out    a.out                 [.] func_inlined (inlined)
> >       0.10%     0.05%  a.out    ld-linux-x86-64.so.2  [.] _dl_relocate_object
> >       0.09%     0.00%  a.out    [unknown]             [k] 0x00007fef811be880
> >       0.09%     0.00%  a.out    ld-linux-x86-64.so.2  [.] _dl_map_object
> >       0.06%     0.00%  a.out    libc.so.6             [.] sysmalloc
> >       0.05%     0.00%  a.out    ld-linux-x86-64.so.2  [.] munmap
> > -     0.05%     0.00%  a.out    ld-linux-x86-64.so.2  [.] mprotect
> > +     0.05%     0.00%  a.out    ld-linux-x86-64.so.2  [.] rtld_timer_accum (inlined)
> > +     0.05%     0.00%  a.out    ld-linux-x86-64.so.2  [.] rtld_timer_stop (inlined)
> > +     0.05%     0.00%  a.out    ld-linux-x86-64.so.2  [.] __mprotect (inlined)
> >       0.05%     0.00%  a.out    libc.so.6             [.] __x86_cacheinfo_ifunc
> > +     0.05%     0.00%  a.out    ld-linux-x86-64.so.2  [.] elf_dynamic_do_Rela (inlined)
> >       0.05%     0.00%  a.out    ld-linux-x86-64.so.2  [.] _dl_map_object_from_fd
> > -     0.04%     0.00%  a.out    ld-linux-x86-64.so.2  [.] mmap64
> > +     0.05%     0.00%  a.out    ld-linux-x86-64.so.2  [.] elf_get_dynamic_info (inlined)
> > +     0.04%     0.00%  a.out    ld-linux-x86-64.so.2  [.] __mmap64 (inlined)
> >       0.04%     0.04%  a.out    ld-linux-x86-64.so.2  [.] _dl_cache_libcmp
> >       0.04%     0.00%  a.out    [unknown]             [.] 0x000000000001b19a
> >       0.04%     0.00%  a.out    [unknown]             [k] 0000000000000000
> > @@ -66,13 +88,15 @@
> >       0.04%     0.04%  a.out    ld-linux-x86-64.so.2  [.] do_lookup_x
> >       0.03%     0.03%  a.out    ld-linux-x86-64.so.2  [.] intel_check_word.constprop.0
> >       0.03%     0.00%  a.out    [unknown]             [.] 0x0000000004000000
> > +     0.03%     0.00%  a.out    ld-linux-x86-64.so.2  [.] intel_check_word (inlined)
> >       0.02%     0.00%  a.out    ld-linux-x86-64.so.2  [.] _dl_start
> >       0.02%     0.02%  a.out    ld-linux-x86-64.so.2  [.] __GI___tunables_init
> >       0.02%     0.00%  a.out    [unknown]             [.] 0x722f3d4b434f535f
> >       0.02%     0.00%  a.out    [unknown]             [.] 0x00007ffebdd69f59
> > +     0.02%     0.00%  a.out    ld-linux-x86-64.so.2  [.] tunable_is_name (inlined)
> >       0.01%     0.00%  a.out    ld-linux-x86-64.so.2  [.] _start
> > ======
> >
> > LBR mode recorded with 'perf record --call-graph=lbr -- ./a.out'
> > ======
> > --- unpatched.lbr       2023-03-16 13:27:50.853253211 +0100
> > +++ patched.lbr 2023-03-16 13:27:56.312104813 +0100
> > @@ -6,58 +6,95 @@
> >  # Samples: 238  of event 'cycles:u'
> >  # Event count (approx.): 193485873
> >  #
> > -# Children      Self  Command  Shared Object         Symbol
> > -# ........  ........  .......  ....................  .................................
> > +# Children      Self  Command  Shared Object         Symbol
> > +# ........  ........  .......  ....................  .............................
> >  #
> >      99.11%    36.87%  a.out    a.out                 [.] main
> >              |
> >              |--62.24%--main
> >              |          |
> > -            |           --17.47%--func_noinline
> > +            |          |--11.05%--func_inlined (inlined)
> > +            |          |          func_noinline
> > +            |          |          func_declared_inlined (inlined)
> > +            |          |
> > +            |           --6.42%--func_noinline
> > +            |                     func_declared_inlined (inlined)
> >              |
> >               --36.87%--_start
> > -                       __libc_start_main@@GLIBC_2.34
> > +                       __libc_start_main_alias_2 (inlined)
> >                         __libc_start_call_main
> >                         main
> >                         |
> > -                       |--24.52%--func_noinline
> > +                       |--17.51%--func_inlined (inlined)
> > +                       |          func_noinline
> > +                       |          func_declared_inlined (inlined)
> > +                       |
> > +                       |--8.45%--func_noinline2
> >                         |
> > -                        --10.01%--func_noinline2
> > +                       |--7.01%--func_noinline
> > +                       |          func_declared_inlined (inlined)
> > +                       |
> > +                        --1.57%--func_declared_inlined (inlined)
> > +                                  func_noinline2
> >
> >      99.11%     0.00%  a.out    a.out                 [.] _start
> >              |
> >              ---_start
> > -               __libc_start_main@@GLIBC_2.34
> > +               __libc_start_main_alias_2 (inlined)
> >                 __libc_start_call_main
> >                 main
> >                 |
> > -               |--41.99%--func_noinline
> > +               |--28.55%--func_inlined (inlined)
> > +               |          func_noinline
> > +               |          func_declared_inlined (inlined)
> > +               |
> > +               |--13.43%--func_noinline
> > +               |          func_declared_inlined (inlined)
> >                 |
> > -                --10.37%--func_noinline2
> > +               |--8.81%--func_noinline2
> > +               |
> > +                --1.57%--func_declared_inlined (inlined)
> > +                          func_noinline2
> >
> > -    99.11%     0.00%  a.out    libc.so.6             [.] __libc_start_main@@GLIBC_2.34
> > +    99.11%     0.00%  a.out    libc.so.6             [.] __libc_start_main_alias_2 (inlined)
> >              |
> > -            ---__libc_start_main@@GLIBC_2.34
> > +            ---__libc_start_main_alias_2 (inlined)
> >                 __libc_start_call_main
> >                 main
> >                 |
> > -               |--41.99%--func_noinline
> > +               |--28.55%--func_inlined (inlined)
> > +               |          func_noinline
> > +               |          func_declared_inlined (inlined)
> > +               |
> > +               |--13.43%--func_noinline
> > +               |          func_declared_inlined (inlined)
> > +               |
> > +               |--8.81%--func_noinline2
> >                 |
> > -                --10.37%--func_noinline2
> > +                --1.57%--func_declared_inlined (inlined)
> > +                          func_noinline2
> >
> >      99.11%     0.00%  a.out    libc.so.6             [.] __libc_start_call_main
> >              |
> >              ---__libc_start_call_main
> >                 main
> >                 |
> > -               |--41.99%--func_noinline
> > +               |--28.55%--func_inlined (inlined)
> > +               |          func_noinline
> > +               |          func_declared_inlined (inlined)
> >                 |
> > -                --10.37%--func_noinline2
> > +               |--13.43%--func_noinline
> > +               |          func_declared_inlined (inlined)
> > +               |
> > +               |--8.81%--func_noinline2
> > +               |
> > +                --1.57%--func_declared_inlined (inlined)
> > +                          func_noinline2
> >
> >      54.44%    44.43%  a.out    a.out                 [.] func_noinline2
> >              |
> >              |--44.43%--_start
> > -            |          __libc_start_main@@GLIBC_2.34
> > +            |          __libc_start_main_alias_2 (inlined)
> >              |          __libc_start_call_main
> >              |          main
> >              |
> > @@ -66,19 +103,42 @@
> >      41.99%    17.47%  a.out    a.out                 [.] func_noinline
> >              |
> >              |--24.52%--func_noinline
> > +            |          func_declared_inlined (inlined)
> >              |
> >               --17.47%--_start
> > -                       __libc_start_main@@GLIBC_2.34
> > +                       __libc_start_main_alias_2 (inlined)
> >                         __libc_start_call_main
> >                         main
> > -                       func_noinline
> > +                       |
> > +                       |--11.05%--func_inlined (inlined)
> > +                       |          func_noinline
> > +                       |          func_declared_inlined (inlined)
> > +                       |
> > +                        --6.42%--func_noinline
> > +                                  func_declared_inlined (inlined)
> > +
> > +    41.99%     0.00%  a.out    a.out                 [.] func_declared_inlined (inlined)
> > +            |
> > +            ---func_declared_inlined (inlined)
> > +
> > +    28.55%     0.00%  a.out    a.out                 [.] func_inlined (inlined)
> > +            |
> > +            ---func_inlined (inlined)
> > +               func_noinline
> > +               func_declared_inlined (inlined)
> > +
> > +     1.57%     0.00%  a.out    a.out                 [.] func_declared_inlined (inlined)
> > +            |
> > +            ---func_declared_inlined (inlined)
> > +               func_noinline2
> >
> >       0.88%     0.00%  a.out    ld-linux-x86-64.so.2  [.] _start
> >              |
> >              ---_start
> >                 _dl_start
> >                 |
> > -                --0.71%--_dl_sysdep_start
> > +                --0.71%--_dl_start_final (inlined)
> > +                          _dl_sysdep_start
> >                            dl_main
> >                            _dl_map_object_deps
> >                            _dl_catch_exception
> > @@ -92,7 +152,8 @@
> >              |
> >              ---_dl_start
> >                 |
> > -                --0.71%--_dl_sysdep_start
> > +                --0.71%--_dl_start_final (inlined)
> > +                          _dl_sysdep_start
> >                            dl_main
> >                            _dl_map_object_deps
> >                            _dl_catch_exception
> > @@ -106,6 +167,20 @@
> >              |
> >              ---_start
> >                 _dl_start
> > +               _dl_start_final (inlined)
> > +               _dl_sysdep_start
> > +               dl_main
> > +               _dl_map_object_deps
> > +               _dl_catch_exception
> > +               openaux
> > +               _dl_map_object
> > +               _dl_map_object_from_fd
> > +               _dl_new_object
> > +               strlen
> > +
> > +     0.71%     0.00%  a.out    ld-linux-x86-64.so.2  [.] _dl_start_final (inlined)
> > +            |
> > +            ---_dl_start_final (inlined)
> >                 _dl_sysdep_start
> >                 dl_main
> >                 _dl_map_object_deps
> > ======
> >
> > No meaningful differences in output with callchains in dwarf mode or when
> > tracing a binary that was compiled with no dwarf debuginfo.
> >
> > Artem Savkov (1):
> >   perf report: append inlines to non-dwarf callchains
> >
> >  tools/perf/util/machine.c | 82 ++++++++++++++++++++-------------------
> >  1 file changed, 43 insertions(+), 39 deletions(-)
> >
> > --
> > 2.39.2
> >
> 

-- 
 Artem