Linus Torvalds wrote: > > On Thu, 11 Jan 2007, Aubrey wrote: > >>Now, my question is, is there a existing way to mount a filesystem >>with O_DIRECT flag? so that I don't need to change anything in my >>system. If there is no option so far, What is the right way to achieve >>my purpose? > > > The right way to do it is to just not use O_DIRECT. > > The whole notion of "direct IO" is totally braindamaged. Just say no. > > This is your brain: O > This is your brain on O_DIRECT: . > > Any questions? > > I should have fought back harder. There really is no valid reason for EVER > using O_DIRECT. You need a buffer whatever IO you do, and it might as well > be the page cache. There are better ways to control the page cache than > play games and think that a page cache isn't necessary. > > So don't use O_DIRECT. Use things like madvise() and posix_fadvise() > instead.
OK, madvise() used with mmap'ed file allows to have reads from a file with zero-copy between kernel/user buffers and don't pollute cache memory unnecessarily. But how about writes? How is to do zero-copy writes to a file and don't pollute cache memory without using O_DIRECT? Do I miss the appropriate interface? > Linus > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
