Re: [PATCH 2/2] perf test stat+shadow_stat.sh: Add threshold for rounding errors

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Sep 12, 2023 at 02:19:26PM +0200, vmolnaro@redhat.com escreveu:
> From: Veronika Molnarova <vmolnaro@redhat.com>
> 
> The test was failing in specific scenarios due to imperfection of FP
> arithmetics. The `bc` command wasn't correctly rounding the result
> of division causing the failure.
> 
> Replace the `bc` with `awk` which should work with more decimal
> places and add a threshold to catch any possible rounding errors.
> The acceptable rounding error is set to 0.01 when the test
> passes with a warning message.
> ---
>  tools/perf/tests/shell/stat+shadow_stat.sh | 30 +++++++++++++++++-----
>  1 file changed, 24 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/tests/shell/stat+shadow_stat.sh b/tools/perf/tests/shell/stat+shadow_stat.sh
> index 0e9cba84e75..73c990fe5ee 100755
> --- a/tools/perf/tests/shell/stat+shadow_stat.sh
> +++ b/tools/perf/tests/shell/stat+shadow_stat.sh
> @@ -4,6 +4,8 @@
>  
>  set -e
>  
> +TRESHOLD=0.015

You got it right on the patch description, I fixed it here as:

⬢[acme@toolbox perf-tools-next]$ git diff
diff --git a/tools/perf/tests/shell/stat+shadow_stat.sh b/tools/perf/tests/shell/stat+shadow_stat.sh
index 626d669158d2d089..a7e4a8f2ad186458 100755
--- a/tools/perf/tests/shell/stat+shadow_stat.sh
+++ b/tools/perf/tests/shell/stat+shadow_stat.sh
@@ -4,7 +4,7 @@

 set -e

-TRESHOLD=0.015
+THRESHOLD=0.015

 # skip if system-wide mode is forbidden
 perf stat -a true > /dev/null 2>&1 || exit 2
@@ -38,7 +38,7 @@ test_global_aggr()
                res=`echo $num $cyc | awk '{printf "%.2f", $1 / $2}'`
                if [ "$ipc" != "$res" ]; then
                        # check the difference from the real result for FP imperfections
-                       diff=`echo $ipc $res $TRESHOLD | \
+                       diff=`echo $ipc $res $THRESHOLD | \
                        awk '{x = ($1 - $2) < 0 ? ($2 - $1) : ($1 - $2); print (x > $3)}'`

                        if [ $diff -eq 1 ]; then
@@ -80,7 +80,7 @@ test_no_aggr()
                res=`echo $num $cyc | awk '{printf "%.2f", $1 / $2}'`
                if [ "$ipc" != "$res" ]; then
                        # check difference from the real result for FP imperfections
-                       diff=`echo $ipc $res $TRESHOLD | \
+                       diff=`echo $ipc $res $THRESHOLD | \
                        awk '{x = ($1 - $2) < 0 ? ($2 - $1) : ($1 - $2); print (x > $3)}'`

                        if [ $diff -eq 1 ]; then
⬢[acme@toolbox perf-tools-next]$