13.6. Bypassing the Buffer Cache: Direct I/O

Starting with kernel 2.4, Linux allows an application to bypass the buffer cache when performing disk I/O, thus transferring data directly from user space to a file or disk device. This is sometimes termed direct I/O or raw I/O.

Note:

The details described here are Linux-specific and are not standardized by SUSv3. Nevertheless, most UNIX implementations provide some form of direct I/O access to devices and files.