// Note: RP doesn't implement relative stats (cpu::usage or mem::usage), or mem::active, or net::anything

               List<String> ids = new ArrayList<String>();

               ids.add(refId);

               Map<String, PerformanceSample> result = vcp.queryLatestPerformance(ids, PerformanceType.cpuAbs);

               System.out.println("     latest cpu sample: " + perf);

            } catch (Exception e) {

               System.out.println("     perf query failed: " + e.getMessage());

            }

         }

      }

      // iterate datacenters to iterate virtual machines

      for (Datacenter dc : getDatacenters()) {

         System.out.println("DC " + dc);

         for (VirtualMachine vm: getVirtualMachines(dc)) {

            // Skip templates, which can't be powered on and have no associated performance data

            if (vm.getConfig().isTemplate()) {

               continue;

            }

            System.out.println("VM " + vm.getName() + ":");

            String refId = MoUtil.morefToString(vm._getRef());

            try {

               String perf;

               Integer[] intervals = vcp.getAllSamplingIntervals(refId);

               int resolution = intervals[0]; // fastest sampling supported

               //System.out.println("   supports sampling intervals: " + listToString(intervals));

               // NB: if you pass times (relative to present, minutes ago) 0,0 (all recent samples): get lots, some are very recent

               // if you pass 60,0 (all samples in last hour): tend to get 11 samples, missing recent one, newest sample can be 9 minutes old

               // if you pass 30,0 (all samples in last half hour): tend to get 5 samples, missing recent one, newest sample can be 9 minutes old; optimization not kicking in

               // if you pass 25,0 (all samples in last 25 min): get 5 samples, including most recent; the "optimization" apparently kicks in

               // best realtime query might be for 5,0? But that involves knowing the interval; our API should have a way to get just newest sample without knowing interval.

               // Anyway, note that 0,0, <30,0 and >30,0 are really different queries.

               Calendar start = vcp.queryVcCurrentTime();

               start.add(Calendar.MINUTE, -20);

               Calendar end = null;

               perf = samplesToString(vcp.queryPerformance(refId, PerformanceType.cpuAbs, resolution, 0, start, end));

               System.out.println("   cpu performance samples: " + perf);

               perf = samplesToString(vcp.queryPerformance(refId, PerformanceType.cpuRel, resolution, 0, start, end));

               System.out.println("   cpu performance samples: " + perf);

               perf = samplesToString(vcp.queryPerformance(refId, PerformanceType.memOccupiedAbs, resolution, 0, start, end));

               System.out.println("   mem-occupy performance samples: " + perf);

               perf = samplesToString(vcp.queryPerformance(refId, PerformanceType.memActiveAbs, resolution, 0, start, end));

               System.out.println("   mem-active performance samples: " + perf);

               perf = samplesToString(vcp.queryPerformance(refId, PerformanceType.memActiveRel, resolution, 0, start, end));

               System.out.println("   mem-active performance samples: " + perf);

               perf = samplesToString(vcp.queryPerformance(refId, PerformanceType.netAbs, resolution, 0, start, end));

               System.out.println("   net performance samples: " + perf);

               List<String> ids = new ArrayList<String>();

               ids.add(refId);

               Map<String, PerformanceSample> result = vcp.queryLatestPerformance(ids, PerformanceType.cpuAbs);

               System.out.println("   latest cpu sample: " + perf);

            } catch (Exception e) {

               System.out.println("   perf query failed: " + e.getMessage());

            }

         }

            List<String> ids = new ArrayList<String>();

            ids.add(refId);

            Map<String, PerformanceSample> result = vcp.queryLatestPerformance(ids, PerformanceType.cpuAbs);

            System.out.println("   'latest' cpu sample: " + perf);

               // we kept the newest sample

               System.out.println("tie! kept newest sample");

               // newest sample is 0, but we didn't use it

               System.out.println("win! avoided invalid 0 sample");

               // latest sample is nonzero, and we didn't use it

               System.out.println("fail! had to skip a valid sample");

            } else {

               // logic error

               System.out.println("inconceivable! not sure how to judge that one");

               String refId = rp.getId();

               List<String> ids = new ArrayList<String>();

               ids.add(refId);

               Map<String, PerformanceSample> result = vcp.queryLatestPerformance(ids, PerformanceType.cpuAbs);

               if (null == sample) {

                  System.out.println("     FAILED: " + rp);

               }

            }

         }