@Test
  public void testPopulatefor5Kbwrites() {
    // RegionAttributes ra = region.getAttributes();
    EvictionCounters lruStats = getLRUStats(region);
    // Put in larger stuff until we start evicting
    int total;
    for (total = 0; lruStats.getEvictions() <= 0; total++) {
      log.info("DEBUG: total " + total + ", evictions " + lruStats.getEvictions());
      int[] array = new int[250];
      array[0] = total;
      region.put(total, array);
    }

    assertEquals(1, lruStats.getEvictions());

    // put another 1mb data which will evicted to disk.
    // final String key = "K";
    final byte[] value = new byte[ENTRY_SIZE];
    Arrays.fill(value, (byte) 77);
    for (int i = 0; i < HALF_OP_COUNT; i++) {
      log.info("DEBUG: total " + total + ", evictions " + lruStats.getEvictions());
      region.put("" + i, value);
    }

    assertEquals(201, lruStats.getEvictions());

    // the next puts will be written to disk
    long startTime = System.currentTimeMillis();
    for (int i = 201; i < OP_COUNT; i++) {
      region.put("" + i, value);
    }
    long endTime = System.currentTimeMillis();
    System.out.println(" done with putting");
    // Now get all the entries which are on disk.
    long startTimeGet = System.currentTimeMillis();
    for (int i = 0; i < HALF_OP_COUNT; i++) {
      region.get("" + i);
    }
    long endTimeGet = System.currentTimeMillis();
    System.out.println(" done with getting");

    region.close(); // closes disk file which will flush all
    // buffers
    float et = endTime - startTime;
    float etSecs = et / 1000f;
    float opPerSec = etSecs == 0 ? 0 : (OP_COUNT / (et / 1000f));
    float bytesPerSec = etSecs == 0 ? 0 : ((OP_COUNT * ENTRY_SIZE) / (et / 1000f));

    String stats = "et=" + et + "ms writes/sec=" + opPerSec + " bytes/sec=" + bytesPerSec;
    log.info(stats);
    System.out.println("Stats for 5kb writes: Perf of Put which is cauing eviction :" + stats);
    // Perf stats for get op
    float etGet = endTimeGet - startTimeGet;
    float etSecsGet = etGet / 1000f;
    float opPerSecGet = etSecsGet == 0 ? 0 : (OP_COUNT / (etGet / 1000f));
    float bytesPerSecGet = etSecsGet == 0 ? 0 : ((OP_COUNT * ENTRY_SIZE) / (etGet / 1000f));

    String statsGet =
        "etGet=" + etGet + "ms gets/sec=" + opPerSecGet + " bytes/sec=" + bytesPerSecGet;
    log.info(statsGet);
    System.out.println("Perf Stats of get which is fauting in :" + statsGet);
  }
Do not change the value OP_COUNT = 400 The test case is dependent on this value.
geode-core/src/integrationTest/java/org/apache/geode/internal/cache/diskPerf/DiskRegOverflowAsyncJUnitPerformanceTest.java