perf test: Add shadow stat test

It calculates IPC from the cycles and instruction counts and compares it
with the shadow stat for both global aggregation (default) and no
aggregation mode.

 $ perf stat -a -A -e cycles,instructions sleep 1

   Performance counter stats for 'system wide':

  CPU0   39,580,880      cycles
  CPU1   45,426,945      cycles
  CPU2   31,151,685      cycles
  CPU3   55,167,421      cycles
  CPU0   17,073,564      instructions      #    0.43  insn per cycle
  CPU1   34,955,764      instructions      #    0.77  insn per cycle
  CPU2   15,688,459      instructions      #    0.50  insn per cycle
  CPU3   34,699,217      instructions      #    0.63  insn per cycle

       1.003275495 seconds time elapsed

In this example, the 'insn per cycle' should be matched to the number
for each cpu.  For CPU2, 0.50 = 15,688,459 / 31,151,685 .

Committer testing:

  # perf test shadow
  78: perf stat metrics (shadow stat) test                            : Ok
  #
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201127041404.390276-2-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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

+#!/bin/sh
+# perf stat metrics (shadow stat) test
+# SPDX-License-Identifier: GPL-2.0
+
+set -e
+
+# skip if system-wide mode is forbidden
+perf stat -a true > /dev/null 2>&1 || exit 2
+
+test_global_aggr()
+{
+	local cyc
+
+	perf stat -a --no-big-num -e cycles,instructions sleep 1  2>&1 | \
+	grep -e cycles -e instructions | \
+	while read num evt hash ipc rest
+	do
+		# skip not counted events
+		if [[ $num == "<not" ]]; then
+			continue
+		fi
+
+		# save cycles count
+		if [[ $evt == "cycles" ]]; then
+			cyc=$num
+			continue
+		fi
+
+		# skip if no cycles
+		if [[ -z $cyc ]]; then
+			continue
+		fi
+
+		# use printf for rounding and a leading zero
+		local res=`printf "%.2f" $(echo "scale=6; $num / $cyc" | bc -q)`
+		if [[ $ipc != $res ]]; then
+			echo "IPC is different: $res != $ipc  ($num / $cyc)"
+			exit 1
+		fi
+	done
+}
+
+test_no_aggr()
+{
+	declare -A results
+
+	perf stat -a -A --no-big-num -e cycles,instructions sleep 1  2>&1 | \
+	grep ^CPU | \
+	while read cpu num evt hash ipc rest
+	do
+		# skip not counted events
+		if [[ $num == "<not" ]]; then
+			continue
+		fi
+
+		# save cycles count
+		if [[ $evt == "cycles" ]]; then
+			results[$cpu]=$num
+			continue
+		fi
+
+		# skip if no cycles
+		local cyc=${results[$cpu]}
+		if [[ -z $cyc ]]; then
+			continue
+		fi
+
+		# use printf for rounding and a leading zero
+		local res=`printf "%.2f" $(echo "scale=6; $num / $cyc" | bc -q)`
+		if [[ $ipc != $res ]]; then
+			echo "IPC is different for $cpu: $res != $ipc  ($num / $cyc)"
+			exit 1
+		fi
+	done
+}
+
+test_global_aggr
+test_no_aggr
+
+exit 0