From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
The current jitter.sh script expects cpumask bits to fit into whatever
the awk interpreter uses for an integer, which clearly does not hold for
even medium-sized systems these days. This means that on a large system,
only the first 32 or 64 CPUs (depending) are subjected to jitter.sh
CPU-time perturbations. This commit therefore computes a given CPU's
cpumask using text manipulation rather than arithmetic shifts.
Reported-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
tools/testing/selftests/rcutorture/bin/jitter.sh | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/rcutorture/bin/jitter.sh b/tools/testing/selftests/rcutorture/bin/jitter.sh
index 188b864..3a856ec 100755
--- a/tools/testing/selftests/rcutorture/bin/jitter.sh
+++ b/tools/testing/selftests/rcutorture/bin/jitter.sh
@@ -67,10 +67,10 @@ do
srand(n + me + systime());
ncpus = split(cpus, ca);
curcpu = ca[int(rand() * ncpus + 1)];
- mask = lshift(1, curcpu);
- if (mask + 0 <= 0)
- mask = 1;
- printf("%#x\n", mask);
+ z = "";
+ for (i = 1; 4 * i <= curcpu; i++)
+ z = z "0";
+ print "0x" 2 ^ (curcpu % 4) z;
}' < /dev/null`
n=$(($n+1))
if ! taskset -p $cpumask $$ > /dev/null 2>&1
--
2.9.5
