Removing 16 node test case for now since it takes way too long and have

dialing down the scales within the CI tests since they should not take
too much time.

eessi/testsuite/tests/apps/espresso/espresso.py

@@ -17,11 +17,23 @@
 from eessi.testsuite.constants import *
 from eessi.testsuite.utils import find_modules, log
 
+def filter_scales_P3M():
+    """
+    Filtering function for filtering scales for P3M test.
+    This is currently required because the 16 node test takes way too long and always fails due to time limit.
+    Once a solution to mesh tuning algorithm is found, where we can specify the mesh sizes for a particular scale,
+    this function can be removed.
+    """
+    return [
+        k for (k, v) in SCALES.items()
+        if v['num_nodes'] != 16
+    ]
+
 
 @rfm.simple_test
 class EESSI_ESPRESSO_P3M_IONIC_CRYSTALS(rfm.RunOnlyRegressionTest):
 
-    scale = parameter(SCALES.keys())
+    scale = parameter(filter_scales_P3M())
     valid_prog_environs = ['default']
     valid_systems = ['*']
     time_limit = '300m'
@@ -55,7 +67,8 @@ def run_after_init(self):
     @run_after('init')
     def set_tag_ci(self):
         """ Setting tests under CI tag. """
-        if (self.benchmark_info[0] in ['mpi.ionic_crystals.p3m']):
+        if (self.benchmark_info[0] in ['mpi.ionic_crystals.p3m']
+            and SCALES[self.scale]['num_nodes'] < 2):
             self.tags.add('CI')
             log(f'tags set to {self.tags}')