Improved error message when partitioning doesn't have enough resources

pacman/operations/partition_algorithms/partition_and_place_partitioner.py

@@ -333,12 +333,18 @@ def _scale_down_resources(self, lo_atom, hi_atom, vertices,
                     used_placements, resource_tracker, lo_atom, hi_atom, graph)
 
             # Attempt to allocate the resources for this vertex on the machine
-            (x, y, p, ip_tags, reverse_ip_tags) = \
-                resource_tracker.allocate_constrained_resources(
-                    used_resources, vertex.constraints)
-            used_placements.append(
-                (vertex, x, y, p, used_resources,
-                 ip_tags, reverse_ip_tags))
+            try:
+                (x, y, p, ip_tags, reverse_ip_tags) = \
+                    resource_tracker.allocate_constrained_resources(
+                        used_resources, vertex.constraints)
+                used_placements.append(
+                    (vertex, x, y, p, used_resources,
+                     ip_tags, reverse_ip_tags))
+            except exceptions.PacmanValueError as e:
+
+                raise exceptions.PacmanValueError(
+                    "Unable to allocate requested resources to"
+                    " vertex {}:\n{}".format(vertex, e))
 
         # reduce data to what the parent requires
         final_placements = list()

pacman/utilities/resource_tracker.py

@@ -697,9 +697,29 @@ def allocate_resources(self, resources, chips=None,
                         reverse_ip_tags_allocated)
 
         # If no chip is available, raise an exception
+        n_cores, n_chips, max_sdram = self._available_resources(usable_chips)
         raise exceptions.PacmanValueError(
             "No resources available to allocate the given resources"
-            " within the given constraints")
+            " within the given constraints:\n"
+            "    Request for CPU: {}, DTCM: {}, SDRAM: {}\n"
+            "    Resources available which meet constraints:"
+            " {} Cores on {} chips, largest SDRAM space: {}".format(
+                resources.cpu.get_value(), resources.dtcm.get_value(),
+                resources.sdram.get_value(), n_cores, n_chips, max_sdram))
+
+    def _available_resources(self, usable_chips):
+        n_cores = 0
+        max_sdram = 0
+        for x, y in usable_chips:
+            chip = self._machine.get_chip_at(x, y)
+            if (x, y) in self._core_tracker:
+                n_cores += len(self._core_tracker[x, y])
+            else:
+                n_cores += len(chip.processors)
+            sdram_available = self._sdram_available(chip, (x, y))
+            if sdram_available > max_sdram:
+                max_sdram = sdram_available
+        return n_cores, len(usable_chips), max_sdram
 
     def get_maximum_constrained_resources_available(self, constraints,
                                                     chips=None):