On Wed, Aug 31 2005, Erik Mouw wrote: > On Wed, Aug 31, 2005 at 10:07:45AM +0200, Jens Axboe wrote: > > On Mon, Aug 29 2005, Erik Mouw wrote: > > > There are four prerequisites for direct IO: > > > - the file needs to be opened with O_DIRECT > > > - the buffer needs to be page aligned (hint: use getpagesize() instead > > > of assuming that a page is 4k > > > - reads and writes need to happen *in* multiples of the soft block size > > > - reads and writes need to happen *at* multiples of the soft block size > > > > Actually, the buffer only needs to be hard block size aligned, same goes > > for the chunk size used for reads/writes. > > OK, so that's different from 2.4 where reads/writes needed to be soft > block aligned and buffers page aligned.
Yes, 2.6 has relaxed the restrictions there somewhat. -- Jens Axboe - 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/
