怎么让MMAP禁止同步？

shineyear

想使用MMAP进行共享内存操作，但不想让系统进行内存与文件的同步，节省磁盘IO，应该怎么做？

shineyear

linux 上好像没有 MAP_NOSYNC

converse

好像没有办法吧.

converse

我大概猜到LZ想做什么,也许你只能像memcache那样使用内存,用多线程而不是多进程了.

思一克

MAP_ANONYMOUS

是做这个用的?

wangqi0021

我记得好像有个宏 能提供这个功能

shineyear

FREE BSD上用MAP_NOSYNC可以，但LINUX上似乎没有～

shineyear

顶一下

放驴娃

用 shm_open 就可以了，不要用 mmap

liyaoshi

msync  flushes  changes made to the in-core copy of a file that was mapped into memory using mmap(2) back to disk.  Without use of this call there
       is no guarantee that changes are written back before munmap(2) is called.  To be more precise, the part of the file that corresponds to the memory
       area starting at start and having length length is updated.  The flags argument may have the bits MS_ASYNC, MS_SYNC and MS_INVALIDATE set, but not
       both MS_ASYNC and MS_SYNC.  MS_ASYNC specifies that an update be scheduled, but the call returns immediately.  MS_SYNC  asks  for  an  update  and
       waits  for  it  to  complete.  MS_INVALIDATE asks to invalidate other mappings of the same file (so that they can be updated with the fresh values
       just written).


默认是不同步的