Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / tools / testing / selftests / vm / hugepage-shm.c

diff --git a/kernel/tools/testing/selftests/vm/hugepage-shm.c b/kernel/tools/testing/selftests/vm/hugepage-shm.c
new file mode 100644 (file)
index 0000000..0d0ef4f
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+++ b/kernel/tools/testing/selftests/vm/hugepage-shm.c
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+/*
+ * hugepage-shm:
+ *
+ * Example of using huge page memory in a user application using Sys V shared
+ * memory system calls.  In this example the app is requesting 256MB of
+ * memory that is backed by huge pages.  The application uses the flag
+ * SHM_HUGETLB in the shmget system call to inform the kernel that it is
+ * requesting huge pages.
+ *
+ * For the ia64 architecture, the Linux kernel reserves Region number 4 for
+ * huge pages.  That means that if one requires a fixed address, a huge page
+ * aligned address starting with 0x800000... will be required.  If a fixed
+ * address is not required, the kernel will select an address in the proper
+ * range.
+ * Other architectures, such as ppc64, i386 or x86_64 are not so constrained.
+ *
+ * Note: The default shared memory limit is quite low on many kernels,
+ * you may need to increase it via:
+ *
+ * echo 268435456 > /proc/sys/kernel/shmmax
+ *
+ * This will increase the maximum size per shared memory segment to 256MB.
+ * The other limit that you will hit eventually is shmall which is the
+ * total amount of shared memory in pages. To set it to 16GB on a system
+ * with a 4kB pagesize do:
+ *
+ * echo 4194304 > /proc/sys/kernel/shmall
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <sys/mman.h>
+
+#ifndef SHM_HUGETLB
+#define SHM_HUGETLB 04000
+#endif
+
+#define LENGTH (256UL*1024*1024)
+
+#define dprintf(x)  printf(x)
+
+/* Only ia64 requires this */
+#ifdef __ia64__
+#define ADDR (void *)(0x8000000000000000UL)
+#define SHMAT_FLAGS (SHM_RND)
+#else
+#define ADDR (void *)(0x0UL)
+#define SHMAT_FLAGS (0)
+#endif
+
+int main(void)
+{
+       int shmid;
+       unsigned long i;
+       char *shmaddr;
+
+       shmid = shmget(2, LENGTH, SHM_HUGETLB | IPC_CREAT | SHM_R | SHM_W);
+       if (shmid < 0) {
+               perror("shmget");
+               exit(1);
+       }
+       printf("shmid: 0x%x\n", shmid);
+
+       shmaddr = shmat(shmid, ADDR, SHMAT_FLAGS);
+       if (shmaddr == (char *)-1) {
+               perror("Shared memory attach failure");
+               shmctl(shmid, IPC_RMID, NULL);
+               exit(2);
+       }
+       printf("shmaddr: %p\n", shmaddr);
+
+       dprintf("Starting the writes:\n");
+       for (i = 0; i < LENGTH; i++) {
+               shmaddr[i] = (char)(i);
+               if (!(i % (1024 * 1024)))
+                       dprintf(".");
+       }
+       dprintf("\n");
+
+       dprintf("Starting the Check...");
+       for (i = 0; i < LENGTH; i++)
+               if (shmaddr[i] != (char)i) {
+                       printf("\nIndex %lu mismatched\n", i);
+                       exit(3);
+               }
+       dprintf("Done.\n");
+
+       if (shmdt((const void *)shmaddr) != 0) {
+               perror("Detach failure");
+               shmctl(shmid, IPC_RMID, NULL);
+               exit(4);
+       }
+
+       shmctl(shmid, IPC_RMID, NULL);
+
+       return 0;
+}