Re: [PATCH v3] perf test: Fix perf stat --bpf-counters on hybrid machines

[Ian Rogers]

On Sun, Mar 22, 2026 at 3:05 PM Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> wrote:
>
> On Wed, Mar 18, 2026 at 11:45:13PM -0700, Namhyung Kim wrote:
> > The test constantly fails on my Intel hybrid machine.  The issue was it
> > has two events in the output even if I only gave it one event.
> >
> >   $ perf stat -e instructions -- perf test -w sqrtloop
> >
> >    Performance counter stats for 'perf test -w sqrtloop':
> >
> >          910,856,421      cpu_atom/instructions/                (28.05%)
> >       14,852,865,997      cpu_core/instructions/                (96.79%)
> >
> >          1.014313341 seconds time elapsed
> >
> >          1.004114000 seconds user
> >          0.008174000 seconds sys
> >
> > Let's modify the awk script to add the values for each line and print
> > the total.  The variable 'i' has a number of input lines that have valid
> > output and variable 'c' has the sum of actual counter values.  That way
> > it should work on any platforms.
>
> Still doesn't pass reliably for me, only once it did work:
>
> ⬢ [acme@toolbx perf-tools]$ git log --oneline -1
> 38415985abcdb64d (HEAD -> perf-tools, number/perf-tools, number/HEAD) perf test: Fix perf stat --bpf-counters on hybrid machines
> ⬢ [acme@toolbx perf-tools]$
> logout
> acme@x1:~/git/perf-tools$
> acme@x1:~/git/perf-tools$
> acme@x1:~/git/perf-tools$ sudo su -
> root@x1:~# perf -v
> perf version 7.0.rc4.g38415985abcd
> root@x1:~# perf test 152
> 152: perf stat --bpf-counters test                                   : FAILED!
> root@x1:~# set -o vi
> root@x1:~# perf test -v 152
> 152: perf stat --bpf-counters test                                   : Ok
> root@x1:~# perf test -v 152
> --- start ---
> test child forked, pid 1829364
> Testing --bpf-counters The difference between 21947395146 and 16947118203 are greater than 20%.
> ---- end(-1) ----
> 152: perf stat --bpf-counters test                                   : FAILED!
> root@x1:~# perf test -v 152
> --- start ---
> test child forked, pid 1829401
> Testing --bpf-counters [Success]
> Testing bpf event modifier The difference between 22461906845 and 17190344465 are greater than 20%.
> ---- end(-1) ----
> 152: perf stat --bpf-counters test                                   : FAILED!
> root@x1:~# perf test -v 152
> --- start ---
> test child forked, pid 1829445
> Testing --bpf-counters The difference between 24210793380 and 16852007232 are greater than 20%.
> ---- end(-1) ----
> 152: perf stat --bpf-counters test                                   : FAILED!
> root@x1:~# perf test -v 152
> --- start ---
> test child forked, pid 1829481
> Testing --bpf-counters The difference between 24293201069 and 17225814972 are greater than 20%.
> ---- end(-1) ----
> 152: perf stat --bpf-counters test                                   : FAILED!
> root@x1:~# grep -m1 "model name" /proc/cpuinfo
> model name      : 13th Gen Intel(R) Core(TM) i7-1365U
> root@x1:~#
>
> acme@x1:~/git/perf-tools$ uname -a
> Linux x1 6.17.12-300.fc43.x86_64 #1 SMP PREEMPT_DYNAMIC Sat Dec 13 05:06:24 UTC 2025 x86_64 GNU/Linux
> acme@x1:~/git/perf-tools$

So I think the real issue here is the multiplexing value, which I've
looked to fix with:
https://lore.kernel.org/lkml/20250716223924.825772-1-irogers@xxxxxxxxxx/

I have a patch to switch to task-clock which is a software event with
a CPU mask of all online CPUs rather than the split seen on hybrid
machines. I'll send it in reply here.

Thanks,
Ian

> > Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>
> > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> > ---
> > v3) make sure to print numbers w/o thousand separators.
> > v2) handle '<not counted>' and '<not supported>'.
> >
> >  tools/perf/tests/shell/stat_bpf_counters.sh | 20 ++++++++++++++++----
> >  1 file changed, 16 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/tests/shell/stat_bpf_counters.sh b/tools/perf/tests/shell/stat_bpf_counters.sh
> > index f43e28a136d3c9bc..35463358b273ce1c 100755
> > --- a/tools/perf/tests/shell/stat_bpf_counters.sh
> > +++ b/tools/perf/tests/shell/stat_bpf_counters.sh
> > @@ -41,8 +41,14 @@ check_counts()
> >  test_bpf_counters()
> >  {
> >       printf "Testing --bpf-counters "
> > -     base_instructions=$(perf stat --no-big-num -e instructions -- $workload 2>&1 | awk '/instructions/ {print $1}')
> > -     bpf_instructions=$(perf stat --no-big-num --bpf-counters -e instructions -- $workload  2>&1 | awk '/instructions/ {print $1}')
> > +     base_instructions=$(perf stat --no-big-num -e instructions -- $workload 2>&1 | \
> > +                             awk -v i=0 -v c=0 '/instructions/ { \
> > +                                     if ($1 != "<not") { i++; c += $1 } \
> > +                             } END { if (i > 0) printf "%.0f", c; else print "<not" }')
> > +     bpf_instructions=$(perf stat --no-big-num --bpf-counters -e instructions -- $workload  2>&1 | \
> > +                             awk -v i=0 -v c=0 '/instructions/ { \
> > +                                     if ($1 != "<not") { i++; c += $1 } \
> > +                             } END { if (i > 0) printf "%.0f", c; else print "<not" }')
> >       check_counts $base_instructions $bpf_instructions
> >       compare_number $base_instructions $bpf_instructions
> >       echo "[Success]"
> > @@ -52,8 +58,14 @@ test_bpf_modifier()
> >  {
> >       printf "Testing bpf event modifier "
> >       stat_output=$(perf stat --no-big-num -e instructions/name=base_instructions/,instructions/name=bpf_instructions/b -- $workload 2>&1)
> > -     base_instructions=$(echo "$stat_output"| awk '/base_instructions/ {print $1}')
> > -     bpf_instructions=$(echo "$stat_output"| awk '/bpf_instructions/ {print $1}')
> > +     base_instructions=$(echo "$stat_output"| \
> > +                             awk -v i=0 -v c=0 '/base_instructions/ { \
> > +                                     if ($1 != "<not") { i++; c += $1 } \
> > +                             } END { if (i > 0) printf "%.0f", c; else print "<not" }')
> > +     bpf_instructions=$(echo "$stat_output"| \
> > +                             awk -v i=0 -v c=0 '/bpf_instructions/ { \
> > +                                     if ($1 != "<not") { i++; c += $1 } \
> > +                             } END { if (i > 0) printf "%.0f", c; else print "<not" }')
> >       check_counts $base_instructions $bpf_instructions
> >       compare_number $base_instructions $bpf_instructions
> >       echo "[Success]"
> > --
> > 2.53.0