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perf test stat+shadow_stat.sh: Add threshold for rounding errors

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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 <vmolnaro@redhat.com>
Acked-by: Michael Petlan <mpetlan@redhat.com>
Link: https://lore.kernel.org/r/20230919150419.23193-1-vmolnaro@redhat.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Veronika Molnarova 2023-09-19 17:02:42 +02:00 committed by Namhyung Kim
parent e49be27e18
commit fa52d995d1
1 changed files with 24 additions and 6 deletions
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30
tools/perf/tests/shell/stat+shadow_stat.sh
View File

@ -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
}