名称
alloc_hugepages, free_hugepages - 分配或释放巨大的页面。
内容简介
|
void *alloc_hugepages(int key, void *addr, size_t len, int prot, int flag) int free_hugepages(void *addr) |
描述
The system calls%uA0alloc_hugepages() and%uA0free_hugepages() were introduced in Linux 2.5.36 and removed again in 2.5.54. They existed only on i386 and ia64 (when built with CONFIG_HUGETLB_PAGE). In Linux 2.4.20 the syscall numbers exist, but the calls return ENOSYS.
On i386 the memory management hardware knows about ordinary pages (4 KiB) and huge pages (2 or 4 MiB). Similarly ia64 knows about huge pages of several sizes. These system calls serve to map huge pages into the process’ memory or to free them again. Huge pages are locked into memory, and are not swapped.
The%uA0key%uA0parameter is an identifier. When zero the pages are private, and not inherited by children. When positive the pages are shared with other applications using the samekey, and inherited by child processes.
The%uA0addr%uA0parameter of%uA0free_hugepages() tells which page is being freed: it was the return value of a call to%uA0alloc_hugepages(). (The memory is first actually freed when all users have released it.) The%uA0addr%uA0parameter of%uA0alloc_hugepages() is a hint, that the kernel may or may not follow. Addresses must be properly aligned.
The%uA0len%uA0parameter is the length of the required segment. It must be a multiple of the huge page size.
The%uA0prot%uA0parameter specifies the memory protection of the segment. It is one of PROT_READ, PROT_WRITE, PROT_EXEC.
The%uA0flag%uA0parameter is ignored, unless%uA0key%uA0is positive. In that case, if%uA0flag%uA0is IPC_CREAT, then a new huge page segment is created when none with the given key existed. If this flag is not set, then ENOENT is returned when no segment with the given key exists.
返回值
On success,%uA0alloc_hugepages() returns the allocated virtual address, andfree_hugepages() returns zero. On error, -1 is returned, and%uA0errno%uA0is set appropriately.
错误
| 标签 | 描述 |
|---|---|
| ENOSYS | The system call is not supported on this kernel. |
遵循于
These calls existed only in Linux 2.5.36 through to 2.5.54. These calls are specific to Linux on Intel processors, and should not be used in programs intended to be portable. Indeed, the system call numbers are marked for reuse, so programs using these may do something random on a future kernel.
文件
/proc/sys/vm/nr_hugepages%uA0Number of configured hugetlb pages. This can be read and written.
/proc/meminfo%uA0Gives info on the number of configured hugetlb pages and on their size in the three variables HugePages_Total, HugePages_Free, Hugepagesize.
注意
The system calls are gone. Now the hugetlbfs filesystem can be used instead. Memory backed by huge pages (if the CPU supports them) is obtained by using%uA0mmap() to map files in this virtual filesystem.
The maximal number of huge pages can be specified using the%uA0hugepages=%uA0boot parameter.