From: Veronika Molnarova Date: Tue, 19 Sep 2023 15:02:42 +0000 (+0200) Subject: perf test stat+shadow_stat.sh: Add threshold for rounding errors X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=fa52d995d1d0b64e75f63571df2e57ba22ff0cb1;p=linux.git perf test stat+shadow_stat.sh: Add threshold for rounding errors 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. Signed-off-by: Veronika Molnarova Acked-by: Michael Petlan Link: https://lore.kernel.org/r/20230919150419.23193-1-vmolnaro@redhat.com Signed-off-by: Namhyung Kim --- diff --git a/tools/perf/tests/shell/stat+shadow_stat.sh b/tools/perf/tests/shell/stat+shadow_stat.sh index a1918a15e36a1..7d9b9d597a500 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 +THRESHOLD=0.015 + # skip if system-wide mode is forbidden perf stat -a true > /dev/null 2>&1 || exit 2 @@ -33,10 +35,18 @@ test_global_aggr() fi # use printf for rounding and a leading zero - res=`printf "%.2f" "$(echo "scale=6; $num / $cyc" | bc -q)"` + res=`echo $num $cyc | awk '{printf "%.2f", $1 / $2}'` if [ "$ipc" != "$res" ]; then - echo "IPC is different: $res != $ipc ($num / $cyc)" - exit 1 + # check the difference from the real result for FP imperfections + diff=`echo $ipc $res $THRESHOLD | \ + awk '{x = ($1 - $2) < 0 ? ($2 - $1) : ($1 - $2); print (x > $3)}'` + + if [ $diff -eq 1 ]; then + echo "IPC is different: $res != $ipc ($num / $cyc)" + exit 1 + fi + + echo "Warning: Difference of IPC is under the threshold" fi done } @@ -67,10 +77,18 @@ test_no_aggr() fi # use printf for rounding and a leading zero - res=`printf "%.2f" "$(echo "scale=6; $num / $cyc" | bc -q)"` + res=`echo $num $cyc | awk '{printf "%.2f", $1 / $2}'` if [ "$ipc" != "$res" ]; then - echo "IPC is different for $cpu: $res != $ipc ($num / $cyc)" - exit 1 + # check difference from the real result for FP imperfections + diff=`echo $ipc $res $THRESHOLD | \ + awk '{x = ($1 - $2) < 0 ? ($2 - $1) : ($1 - $2); print (x > $3)}'` + + if [ $diff -eq 1 ]; then + echo "IPC is different: $res != $ipc ($num / $cyc)" + exit 1 + fi + + echo "Warning: Difference of IPC is under the threshold" fi done }