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authorLinus Torvalds <torvalds@linux-foundation.org>2012-03-28 17:19:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-28 17:19:28 -0700
commit532bfc851a7475fb6a36c1e953aa395798a7cca7 (patch)
treea7892e5a31330dd59f31959efbe9fda1803784fd /tools/testing/selftests/vm/hugepage-mmap.c
parent0195c00244dc2e9f522475868fa278c473ba7339 (diff)
parent8da00edc1069f01c34510fa405dc15d96c090a3f (diff)
Merge branch 'akpm' (Andrew's patch-bomb)
Merge third batch of patches from Andrew Morton: - Some MM stragglers - core SMP library cleanups (on_each_cpu_mask) - Some IPI optimisations - kexec - kdump - IPMI - the radix-tree iterator work - various other misc bits. "That'll do for -rc1. I still have ~10 patches for 3.4, will send those along when they've baked a little more." * emailed from Andrew Morton <akpm@linux-foundation.org>: (35 commits) backlight: fix typo in tosa_lcd.c crc32: add help text for the algorithm select option mm: move hugepage test examples to tools/testing/selftests/vm mm: move slabinfo.c to tools/vm mm: move page-types.c from Documentation to tools/vm selftests/Makefile: make `run_tests' depend on `all' selftests: launch individual selftests from the main Makefile radix-tree: use iterators in find_get_pages* functions radix-tree: rewrite gang lookup using iterator radix-tree: introduce bit-optimized iterator fs/proc/namespaces.c: prevent crash when ns_entries[] is empty nbd: rename the nbd_device variable from lo to nbd pidns: add reboot_pid_ns() to handle the reboot syscall sysctl: use bitmap library functions ipmi: use locks on watchdog timeout set on reboot ipmi: simplify locking ipmi: fix message handling during panics ipmi: use a tasklet for handling received messages ipmi: increase KCS timeouts ipmi: decrease the IPMI message transaction time in interrupt mode ...
Diffstat (limited to 'tools/testing/selftests/vm/hugepage-mmap.c')
-rw-r--r--tools/testing/selftests/vm/hugepage-mmap.c92
1 files changed, 92 insertions, 0 deletions
diff --git a/tools/testing/selftests/vm/hugepage-mmap.c b/tools/testing/selftests/vm/hugepage-mmap.c
new file mode 100644
index 00000000000..a10f310d236
--- /dev/null
+++ b/tools/testing/selftests/vm/hugepage-mmap.c
@@ -0,0 +1,92 @@
+/*
+ * hugepage-mmap:
+ *
+ * Example of using huge page memory in a user application using the mmap
+ * system call. Before running this application, make sure that the
+ * administrator has mounted the hugetlbfs filesystem (on some directory
+ * like /mnt) using the command mount -t hugetlbfs nodev /mnt. In this
+ * example, the app is requesting memory of size 256MB that is backed by
+ * 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.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+
+#define FILE_NAME "huge/hugepagefile"
+#define LENGTH (256UL*1024*1024)
+#define PROTECTION (PROT_READ | PROT_WRITE)
+
+/* Only ia64 requires this */
+#ifdef __ia64__
+#define ADDR (void *)(0x8000000000000000UL)
+#define FLAGS (MAP_SHARED | MAP_FIXED)
+#else
+#define ADDR (void *)(0x0UL)
+#define FLAGS (MAP_SHARED)
+#endif
+
+static void check_bytes(char *addr)
+{
+ printf("First hex is %x\n", *((unsigned int *)addr));
+}
+
+static void write_bytes(char *addr)
+{
+ unsigned long i;
+
+ for (i = 0; i < LENGTH; i++)
+ *(addr + i) = (char)i;
+}
+
+static int read_bytes(char *addr)
+{
+ unsigned long i;
+
+ check_bytes(addr);
+ for (i = 0; i < LENGTH; i++)
+ if (*(addr + i) != (char)i) {
+ printf("Mismatch at %lu\n", i);
+ return 1;
+ }
+ return 0;
+}
+
+int main(void)
+{
+ void *addr;
+ int fd, ret;
+
+ fd = open(FILE_NAME, O_CREAT | O_RDWR, 0755);
+ if (fd < 0) {
+ perror("Open failed");
+ exit(1);
+ }
+
+ addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, fd, 0);
+ if (addr == MAP_FAILED) {
+ perror("mmap");
+ unlink(FILE_NAME);
+ exit(1);
+ }
+
+ printf("Returned address is %p\n", addr);
+ check_bytes(addr);
+ write_bytes(addr);
+ ret = read_bytes(addr);
+
+ munmap(addr, LENGTH);
+ close(fd);
+ unlink(FILE_NAME);
+
+ return ret;
+}