// Make sure this cloud actually can provision for this label.
                    if (c.canProvision(label)) {
                        // provisioning a new node should be conservative --- for example if exceeWorkload is 1.4,
                        // we don't want to allocate two nodes but just one.
                        // OTOH, because of the exponential decay, even when we need one slave, excess workload is always
                        // something like 0.95, in which case we want to allocate one node.
                        // so the threshold here is 1-MARGIN, and hence floor(excessWorkload+MARGIN) is needed to handle this.

                        int workloadToProvision = (int) Math.round(Math.floor(excessWorkload + m));

                        for (CloudProvisioningListener cl : CloudProvisioningListener.all())
                            // consider displaying reasons in a future cloud ux
                            if (cl.canProvision(c,label,workloadToProvision) != null)
                                break CLOUD;

                        Collection<PlannedNode> additionalCapacities = c.provision(label, workloadToProvision);

                        for (CloudProvisioningListener cl : CloudProvisioningListener.all())
                            cl.onStarted(c, label, additionalCapacities);

                        for (PlannedNode ac : additionalCapacities) {
                            excessWorkload -= ac.numExecutors;
                            LOGGER.info("Started provisioning "+ac.displayName+" from "+c.name+" with "+ac.numExecutors+" executors. Remaining excess workload:"+excessWorkload);
                        }
                        pendingLaunches.addAll(additionalCapacities);
                    }