复制 intget_or_create_shared_memory(key_t key,int size,int flag){int shmid=shmget(key,size,flag);//成功返回共享内存标识符,失败返回-1if(shmid==-1){cout<<"共享内存创建失败,原因是:"<<strerror(errno)<<endl;exit(2);}returnshmid;}intcreate_shared_memory(key_t key,int size){returnget_...
int get_or_create_shared_memory(key_t key, int size, int flag){int shmid = shmget(key, size, flag);//成功返回共享内存标识符,失败返回-1if(shmid == -1){cout << "共享内存创建失败,原因是:" << strerror(errno) << endl;exit(2);}return shmid;}int create_shared_memory(key_t key, ...
Shared memory is responsible for the smooth operation of your system; it acts as a space that multiple programs can access at once. This enables those programs to communicate in sync, while avoiding file redundancy. Shared memory can exist in the system's physical RAM or the swap file (which...
shm_close, /* close - callback for when the vm-area is released */ NULL, /* no need to sync pages at unmap */ NULL, /* protect */ NULL, /* sync */ NULL, /* advise */ shm_nopage, /* nopage */ NULL, /* wppage */ shm_swapout /* swapout */ }; shm_vm_ops的nopag...
NULL,/* sync */ NULL,/* advise */ shm_nopage,/* nopage */ NULL,/* wppage */ shm_swapout/* swapout */ }; shm_vm_ops 的 nopage 回调为 shm_nopage 函数,也就是说,当发生页缺失异常时将会调用此函数来恢复内存的映射。 从上面的代码可看出, shmat 函数只是申请了进程的虚拟内存空间,而...
将内存中数据强制先刷新到磁盘中: sync; sleep 3; sync 清理缓存: echo 3 > /proc/sys/vm/drop_caches 表示清除pagecache和slab分配器中的缓存对象 echo 1 > /proc/sys/vm/drop_caches:表示清除pagecache。 echo 2 > /proc/sys/vm/drop_caches:表示清除回收slab分配器中的对象(包括目录项缓存和inode缓存...
NULL, /* sync */ NULL, /* advise */ shm_nopage, /* nopage */ NULL, /* wppage */ shm_swapout /* swapout */ }; shm_vm_ops的nopage回调为shm_nopage()函数,也就是说,当发生页缺失异常时将会调用此函数来恢复内存的映射。
sync echo 1 > /proc/sys/vm/drop_caches #清除后要还原系统默认配置: echo 0 > /proc/sys/vm/drop_caches #查看设置 sysctl -a | grep drop_caches 补充: echo 字符串 > 文件 就是把字符串内容从定向到文件中 这时查看 free 可以看到 cached 降低了很多 ...
staticstruct vm_operations_struct shm_vm_ops = {shm_open, /*open- callbackfora new vm-areaopen*/shm_close, /*close- callbackforwhenthe vm-areaisreleased */NULL, /*noneedtosync pagesatunmap */NULL, /* protect */NULL, /* sync */NULL, /* advise */shm_nopage, /* nopage */NU...
flags:模式的设置--flags参数取值:MS_ASYNC:异步写MS_SYNC:同步写MS_INVALIDATE:使高速缓存的数据失效 *MS_ASYNC和MS_SYNC的区别,一旦写操作已经由内核排入队列,MS_ASYNC立即返回,MS_SYNC则要等到写操作完成后才返回。 代码样例: Demo1: 文件操作--利用内存映射读文件的第一行 ...