Commit fa52d995 authored by Veronika Molnarova's avatar Veronika Molnarova Committed by Namhyung Kim
Browse files

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: default avatarVeronika Molnarova <vmolnaro@redhat.com>
Acked-by: default avatarMichael Petlan <mpetlan@redhat.com>
Link: https://lore.kernel.org/r/20230919150419.23193-1-vmolnaro@redhat.com


Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
parent e49be27e

tools/perf/tests/shell/stat+shadow_stat.sh

+24 −6
Original line number Diff line number Diff line
@@ -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
@@ -33,11 +35,19 @@ 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

			# 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

}
@@ -67,11 +77,19 @@ 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)"

			# 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

}