/* * 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 #include #include #include #include #include #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; } />
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authorLinus Torvalds <torvalds@linux-foundation.org>2017-02-06 14:16:23 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-06 14:16:23 -0800
commit396bf4cd835e62d70fad4a03a8963e61f19021f2 (patch)
tree79ac8f33554260fea1a8d43e6f8c4c5460115f45 /tools/thermal
parentd5adbfcd5f7bcc6fa58a41c5c5ada0e5c826ce2c (diff)
parent7c2cf1c4615cc2f576d0604406cdf0065f00b83b (diff)
Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
Pull crypto fixes from Herbert Xu: - use-after-free in algif_aead - modular aesni regression when pcbc is modular but absent - bug causing IO page faults in ccp - double list add in ccp - NULL pointer dereference in qat (two patches) - panic in chcr - NULL pointer dereference in chcr - out-of-bound access in chcr * 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: crypto: chcr - Fix key length for RFC4106 crypto: algif_aead - Fix kernel panic on list_del crypto: aesni - Fix failure when pcbc module is absent crypto: ccp - Fix double add when creating new DMA command crypto: ccp - Fix DMA operations when IOMMU is enabled crypto: chcr - Check device is allocated before use crypto: chcr - Fix panic on dma_unmap_sg crypto: qat - zero esram only for DH85x devices crypto: qat - fix bar discovery for c62x
Diffstat (limited to 'tools/thermal')