experiments/power: Sleep until dhrystone dies

Killall does not work on background processes.
Instead, just sleep until the benchmark has finished.
A long sleep will also allow the hardware to cool down
and stop power measurements to be affected by heating.

Test: ./run_cpu_frequency.py

Change-Id: I78528aea52adb6c0e63755b20a0b8103406afb3f

1 files changed, 5 insertions, 3 deletions

diff --git a/experiments/power/eas/run_cpu_frequency.py b/experiments/power/eas/run_cpu_frequency.py
index ecb1fb3..965ed7a 100755
--- a/experiments/power/eas/run_cpu_frequency.py
+++ b/experiments/power/eas/run_cpu_frequency.py
@@ -147,7 +147,7 @@ def experiment():
                 # Run dhrystone benchmark for longer than the requested time so
                 # we have extra time to set up the measuring device
                 target.execute('nohup {} -t {} -r {}  2>/dev/null 1>/dev/null'
-                        ' &'.format(dhrystone, len(on_cpus), args.duration_s+60))
+                        ' &'.format(dhrystone, len(on_cpus), args.duration_s+30))
 
                 # Start measuring
                 te.emeter.reset()
@@ -158,8 +158,10 @@ def experiment():
                 # Stop measuring
                 te.emeter.report(outdir, out_energy=energy, out_samples=samples)
 
-                # Kill dhrystone so it does not affect the next measurement
-                pids = target.killall('dhyrstone')
+                # Since we are using nohup, the benchmark doesn't show up in
+                # process list. Instead sleep until we can be sure the benchmark
+                # is dead.
+                sleep(30)
 
     # Restore all the cpus
     target.hotplug.online_all()