On 12/02/2015 09:51 PM, Dallas Clement wrote: > On Wed, Dec 2, 2015 at 8:38 PM, Phil Turmel <philip@xxxxxxxxxx> wrote: >> On 12/02/2015 09:33 PM, Dallas Clement wrote: >> >>> I'm not sure that the sync=1 has any effect in this case where I've >>> got direct=1 set (for non buffered I/O). I think the sync=1 flag only >>> matters for buffered I/O. I really shouldn't be setting that flag at >>> all. >> >> It's substantially different from direct=1. O_DIRECT just bypasses the >> kernel's caches. O_SYNC flushes the file data and filesystem metadata, >> and kills the device caches and queues. > > Isn't O_SYNC only applicable for buffered I/O or going through the > kernel caches? If I'm using O_DIRECT, seems like it should just > ignore this flag. O_SYNC is orthogonal to whether the kernel caches are involved. It is about ensuring that data *and* metadata are safely written all the way to permanent media. Phil -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
