> Marco wrote: > > To enable direct > > I/O at all times for all regular files requires either that > > applications be modified to include the O_DIRECT flag on all file > > opens, or that a new filesystem be used that always performs direct > > I/O by default." > > This could be done as well by just introducing a "direct_io_only" > mount option to a file-system which would need this feature.
A mount option would not be the right way. Mount options are for things that are characteristic of the way you're going to access the files. _This_ is a characteristic of the block device. So if one were to make this memory accessible with a block device, it would make more sense to have a block device ioctl. And it wouldn't ask the question, "should I use direct I/O only," but "does this device have the performance characteristics of a classic disk drive?" But it's possible that there's just no advantage to having a block device in the stack here. When unix block devices were invented, their main purpose was that they could reorder reads and writes and do buffering and caching -- all things essential for disk drives. We don't want to stretch the concept too far. -- Bryan Henderson IBM Almaden Research Center San Jose CA Storage Systems -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
