[tip: core/rcu] torture: Handle systems lacking the mpstat command

[tip-bot2 for Paul E. McKenney]

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     b8dfff975c370912c7ac633ca3e4a812dcd38f96
Gitweb:        https://git.kernel.org/tip/b8dfff975c370912c7ac633ca3e4a812dcd38f96
Author:        Paul E. McKenney <paulmck@xxxxxxxxxx>
AuthorDate:    Mon, 21 Oct 2019 08:38:00 -07:00
Committer:     Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Mon, 09 Dec 2019 13:00:27 -08:00

torture: Handle systems lacking the mpstat command

The rcutorture scripting uses the mpstat command to determine how much
the system is being used, and adjusts make's -j argument accordingly.
However, mpstat isn't installed by default, so it would be good if the
scripting does something useful when mpstat isn't present.

This commit therefore makes the scripts assumes that if mpstat is not
present, they are free to use all the CPUs.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 tools/testing/selftests/rcutorture/bin/cpus2use.sh | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/rcutorture/bin/cpus2use.sh b/tools/testing/selftests/rcutorture/bin/cpus2use.sh
index 4e94855..1dbfb62 100755
--- a/tools/testing/selftests/rcutorture/bin/cpus2use.sh
+++ b/tools/testing/selftests/rcutorture/bin/cpus2use.sh
@@ -15,8 +15,15 @@ then
 	exit 0
 fi
 ncpus=`grep '^processor' /proc/cpuinfo | wc -l`
-idlecpus=`mpstat | tail -1 | \
-	awk -v ncpus=$ncpus '{ print ncpus * ($7 + $NF) / 100 }'`
+if mpstat -V > /dev/null 2>&1
+then
+	idlecpus=`mpstat | tail -1 | \
+		awk -v ncpus=$ncpus '{ print ncpus * ($7 + $NF) / 100 }'`
+else
+	# No mpstat command, so use all available CPUs.
+	echo The mpstat command is not available, so greedily using all CPUs.
+	idlecpus=$ncpus
+fi
 awk -v ncpus=$ncpus -v idlecpus=$idlecpus < /dev/null '
 BEGIN {
 	cpus2use = idlecpus;