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SubjectRe: A problem about DIRECT IO on ext3


--- li nux <lnxluv@yahoo.com> wrote:
>
>
> --- Jens Axboe <axboe@suse.de> 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.
> >
> > --
> > Jens Axboe
> >
On 2.4 the open call succeeds with O_DIRECT
but read returns -EINVAL for any block size (512,
1024 ..16384)

open("/tmp/midstress_idx10",
O_RDWR|O_CREAT|O_DIRECT|O_LARGEFILE, 01001101270) =
3
read(3, 0xbfffdc40, 16384) = -1 EINVAL (Invalid
argument)
how to correct this problem ?





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