Re: A problem about DIRECT IO on ext3

[Erik Mouw]

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.


Erik

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