40 41 /* Note: It would be nice to verify the minimal supported heap size (2m) here, 42 * but we align the heap size based on the card table size. And the card table 43 * size is aligned based on the minimal pages size provided by the os. This 44 * means that on most platforms, where the minimal page size is 4k, we get a 45 * minimal heap size of 2m but on Solaris/Sparc we have a page size of 8k and 46 * get a minimal heap size of 4m. And on platforms where the page size is 64k 47 * we get a minimal heap size of 32m. We never use large pages for the card table. 48 * 49 * There is also no check in the VM for verifying that the maximum heap size 50 * is larger than the supported minimal heap size. This means that specifying 51 * -Xmx1m on the command line is fine but will give a heap of 2m (or 4m or 32m). 52 * 53 * To work around these rather strange behaviors this test uses -Xmx2m but then 54 * calculates what the expected heap size should be. The calculation is a 55 * simplified version of the code in the VM. We assume that the card table will 56 * use one page. Each byte in the card table corresponds to 512 bytes on the heap. 57 * So, the expected heap size is page_size * 512. 58 */ 59 60 import com.oracle.java.testlibrary.*; 61 import com.sun.management.HotSpotDiagnosticMXBean; 62 import java.lang.management.ManagementFactory; 63 import static com.oracle.java.testlibrary.Asserts.*; 64 65 import sun.hotspot.WhiteBox; 66 67 public class TestSmallHeap { 68 69 public static void main(String[] args) { 70 WhiteBox wb = WhiteBox.getWhiteBox(); 71 int pageSize = wb.getVMPageSize(); 72 int heapBytesPerCard = 512; 73 long expectedMaxHeap = pageSize * heapBytesPerCard; 74 String maxHeap 75 = ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class) 76 .getVMOption("MaxHeapSize").getValue(); 77 assertEQ(Long.parseLong(maxHeap), expectedMaxHeap); 78 } 79 } | 40 41 /* Note: It would be nice to verify the minimal supported heap size (2m) here, 42 * but we align the heap size based on the card table size. And the card table 43 * size is aligned based on the minimal pages size provided by the os. This 44 * means that on most platforms, where the minimal page size is 4k, we get a 45 * minimal heap size of 2m but on Solaris/Sparc we have a page size of 8k and 46 * get a minimal heap size of 4m. And on platforms where the page size is 64k 47 * we get a minimal heap size of 32m. We never use large pages for the card table. 48 * 49 * There is also no check in the VM for verifying that the maximum heap size 50 * is larger than the supported minimal heap size. This means that specifying 51 * -Xmx1m on the command line is fine but will give a heap of 2m (or 4m or 32m). 52 * 53 * To work around these rather strange behaviors this test uses -Xmx2m but then 54 * calculates what the expected heap size should be. The calculation is a 55 * simplified version of the code in the VM. We assume that the card table will 56 * use one page. Each byte in the card table corresponds to 512 bytes on the heap. 57 * So, the expected heap size is page_size * 512. 58 */ 59 60 import jdk.test.lib.*; 61 import com.sun.management.HotSpotDiagnosticMXBean; 62 import java.lang.management.ManagementFactory; 63 import static jdk.test.lib.Asserts.*; 64 65 import sun.hotspot.WhiteBox; 66 67 public class TestSmallHeap { 68 69 public static void main(String[] args) { 70 WhiteBox wb = WhiteBox.getWhiteBox(); 71 int pageSize = wb.getVMPageSize(); 72 int heapBytesPerCard = 512; 73 long expectedMaxHeap = pageSize * heapBytesPerCard; 74 String maxHeap 75 = ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class) 76 .getVMOption("MaxHeapSize").getValue(); 77 assertEQ(Long.parseLong(maxHeap), expectedMaxHeap); 78 } 79 } |