Re: A problem about DIRECT IO on ext3

[li nux <lnxluv@yahoo.com>]

--- 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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