/* * Example of using hugepage memory in a user application using the mmap * system call with MAP_HUGETLB flag. Before running this program make * sure the administrator has allocated enough default sized huge pages * to cover the 256 MB allocation. * * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. * That means the addresses starting with 0x800000... will need to be * specified. Specifying a fixed address is not required on ppc64, i386 * or x86_64. */ #include #include #include #include #include #define LENGTH (256UL*1024*1024) #define PROTECTION (PROT_READ | PROT_WRITE) #ifndef MAP_HUGETLB #define MAP_HUGETLB 0x40000 /* arch specific */ #endif /* Only ia64 requires this */ #ifdef __ia64__ #define ADDR (void *)(0x8000000000000000UL) #define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED) #else #define ADDR (void *)(0x0UL) #define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) #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 ret; addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, 0, 0); if (addr == MAP_FAILED) { perror("mmap"); exit(1); } printf("Returned address is %p\n", addr); check_bytes(addr); write_bytes(addr); ret = read_bytes(addr); /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */ if (munmap(addr, LENGTH)) { perror("munmap"); exit(1); } return ret; } eecommitdiff
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016-05-04 14:12:42 -0400
committerMike Snitzer <snitzer@redhat.com>2016-05-13 09:04:20 -0400
commit202bae52934d4eb79ffaebf49f49b1cc64d8e40b (patch)
tree41d78f7ee52b69471b77ac74d07ac4ae212a2c49
parent3dba53a958a758fe7bed5002f6a2846e1acefe8e (diff)
dm thin: unroll issue_discard() to create longer discard bio chains
There is little benefit to doing this but it does structure DM thinp's code to more cleanly use the __blkdev_issue_discard() interface -- particularly in passdown_double_checking_shared_status(). Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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