> > I agree that msync(MS_ASYNC) has no semantics if time is ignored. > > But it's a useful way to tell the OS that the page is not going > > to be dirtied again. > > Just to clarify, here's the header comment for sys_msync(): > > /* > * MS_SYNC syncs the entire file - including mappings. > * > * MS_ASYNC does not start I/O (it used to, up to 2.5.67). > * Nor does it marks the relevant pages dirty (it used to up to 2.6.17). > * Now it doesn't do anything, since dirty pages are properly tracked. > * > * The application may now run fsync() to > * write out the dirty pages and wait on the writeout and check the result. > * Or the application may run fadvise(FADV_DONTNEED) against the fd to start > * async writeout immediately. > * So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to > * applications. > */ > > It's actually wrong about FADV_DONTNEED, which I think doesn't start > writeout either. So there you have it ;)
Sorry, FADV_DONTNEED _does_ seem to start writeout, but it does it indiscriminately, not just on the specified range. That should be easy to fix though. Miklos - 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/
