Re: perf probe + uprobes missing events

From: Arnaldo Carvalho de Melo
Date: Mon Apr 06 2020 - 10:54:58 EST

Em Mon, Apr 06, 2020 at 11:53:56AM -0300, Arnaldo Carvalho de Melo escreveu:
> Hi Masami,

Sorry, details about the system:

[root@five ~]# uname -a
Linux five 5.5.10-200.fc31.x86_64 #1 SMP Wed Mar 18 14:21:38 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
[root@five ~]# perf -vv
perf version 5.6.gea05cf482862
dwarf: [ on ] # HAVE_DWARF_SUPPORT
dwarf_getlocations: [ on ] # HAVE_DWARF_GETLOCATIONS_SUPPORT
glibc: [ on ] # HAVE_GLIBC_SUPPORT
gtk2: [ on ] # HAVE_GTK2_SUPPORT
syscall_table: [ on ] # HAVE_SYSCALL_TABLE_SUPPORT
libbfd: [ on ] # HAVE_LIBBFD_SUPPORT
libelf: [ on ] # HAVE_LIBELF_SUPPORT
libnuma: [ on ] # HAVE_LIBNUMA_SUPPORT
numa_num_possible_cpus: [ on ] # HAVE_LIBNUMA_SUPPORT
libperl: [ on ] # HAVE_LIBPERL_SUPPORT
libpython: [ on ] # HAVE_LIBPYTHON_SUPPORT
libslang: [ on ] # HAVE_SLANG_SUPPORT
libcrypto: [ on ] # HAVE_LIBCRYPTO_SUPPORT
libunwind: [ on ] # HAVE_LIBUNWIND_SUPPORT
libdw-dwarf-unwind: [ on ] # HAVE_DWARF_SUPPORT
zlib: [ on ] # HAVE_ZLIB_SUPPORT
lzma: [ on ] # HAVE_LZMA_SUPPORT
get_cpuid: [ on ] # HAVE_AUXTRACE_SUPPORT
bpf: [ on ] # HAVE_LIBBPF_SUPPORT
aio: [ on ] # HAVE_AIO_SUPPORT
zstd: [ on ] # HAVE_ZSTD_SUPPORT
[root@five ~]# rpm -q elfutils
elfutils-0.178-7.fc31.x86_64
[root@five ~]#

> I'm trying to use 'perf probe' to debug 'perf test', but I'm not
> getting repeatable results, take a look:
>
> I'm trying to figure out which expresssions are _really_ being tested
> byu the 'perf test expr' testcase, so I added a probe to the
> expr__parse() routine, asking for the expr string to be printed:
>
> [root@five ~]# perf probe -x ~/bin/perf -L expr__parse
> <expr__parse@/home/acme/git/perf/tools/perf/util/expr.c:0>
> 0 int expr__parse(double *final_val, struct expr_parse_ctx *ctx, const char *expr, int runtime)
> 1 {
> 2 return __expr__parse(final_val, ctx, expr, EXPR_PARSE, runtime) ? -1 : 0;
> 3 }
>
> static bool
> already_seen(const char *val, const char *one, const char **other,
>
> [root@five ~]#
>
> [root@five ~]# perf probe -x ~/bin/perf expr__parse expr:string
> Target program is compiled without optimization. Skipping prologue.
> Probe on address 0x5cb11b to force probing at the function entry.
>
> Added new event:
> probe_perf:expr__parse (on expr__parse in /home/acme/bin/perf with expr:string)
>
> You can now use it in all perf tools, such as:
>
> perf record -e probe_perf:expr__parse -aR sleep 1
>
> [root@five ~]#
>
> [root@five ~]# perf trace -e probe_perf:expr_* perf test -F expr
> 7: Simple expression parser : Ok
> 0.000 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1+1")
> 0.015 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "FOO+BAR")
> 0.018 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "(BAR/2)%2")
> 0.020 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1 - -4")
> 0.023 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "(FOO-1)*2 + (BAR/2)%2 - -4")
> 0.026 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1-1 | 1")
> 0.029 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1-1 & 1")
> 0.031 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "min(1,2) + 1")
> 0.034 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "max(1,2) + 1")
> 0.036 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1+1 if 3*4 else 0")
> 0.039 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "FOO/0")
> 0.041 :2994175/2994175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "BAR/")
> [root@five ~]# perf trace -e probe_perf:expr_* perf test -F expr
> 7: Simple expression parser : Ok
> 0.000 perf/2996042 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1+1")
> 0.021 perf/2996042 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "FOO+BAR")
> 0.025 perf/2996042 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "(BAR/2)%2")
> 0.029 perf/2996042 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1 - -4")
> 0.033 perf/2996042 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "(FOO-1)*2 + (BAR/2)%2 - -4")
> 0.041 perf/2996042 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1-1 | 1")
> 0.044 perf/2996042 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1-1 & 1")
> [root@five ~]# perf trace -e probe_perf:expr_* perf test -F expr
> 7: Simple expression parser : Ok
> 0.000 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1+1")
> 0.020 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "FOO+BAR")
> 0.025 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "(BAR/2)%2")
> 0.029 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1 - -4")
> 0.032 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "(FOO-1)*2 + (BAR/2)%2 - -4")
> 0.037 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1-1 | 1")
> 0.040 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1-1 & 1")
> 0.043 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "min(1,2) + 1")
> 0.046 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "max(1,2) + 1")
> 0.049 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1+1 if 3*4 else 0")
> 0.053 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "FOO/0")
> 0.056 perf/2996416 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "BAR/")
> [root@five ~]# perf trace -e probe_perf:expr_* perf test -F expr
> 7: Simple expression parser : Ok
> [root@five ~]# perf trace -e probe_perf:expr_* perf test -F expr
> 7: Simple expression parser : Ok
> [root@five ~]# perf trace -e probe_perf:expr_* perf test -F expr
> 7: Simple expression parser : Ok
> [root@five ~]# perf trace -e probe_perf:expr_* perf test -F expr
> 7: Simple expression parser : Ok
> [root@five ~]# perf trace -e probe_perf:expr_* perf test -F expr
> 7: Simple expression parser : Ok
> 0.000 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1+1")
> 0.014 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "FOO+BAR")
> 0.017 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "(BAR/2)%2")
> 0.021 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1 - -4")
> 0.024 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "(FOO-1)*2 + (BAR/2)%2 - -4")
> 0.030 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1-1 | 1")
> 0.032 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1-1 & 1")
> 0.035 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "min(1,2) + 1")
> 0.038 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "max(1,2) + 1")
> 0.040 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "1+1 if 3*4 else 0")
> 0.044 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "FOO/0")
> 0.046 :2998175/2998175 probe_perf:expr__parse(__probe_ip: 6074674, expr_string: "BAR/")
> [root@five ~]#
>
>
> Do you have any idea why that happens?
>
> - Arnaldo

--

- Arnaldo