Subject: Re: maximum size of 8KB in copyin\out
To: Jason Thorpe <firstname.lastname@example.org>
From: Maen Suleiman <email@example.com>
Date: 03/10/2007 02:07:35
Sorry I missed "Matt Thomas" reply. I will try raw device.
On 3/10/07, Maen Suleiman <firstname.lastname@example.org> wrote:
> What do you think the reason we are seeing maximum of 8KB on
> copyin\out although we are telling dd to use 128KB block size. we are
> reading from SATA disk (SCSI implementation) or USB disk .
> On 3/10/07, Jason Thorpe <email@example.com> wrote:
> > On Mar 9, 2007, at 2:14 PM, Maen Suleiman wrote:
> > > Hi,
> > >
> > > We are implmenting copyin\out using DMA engine, and we have noticed
> > > that the maximum buffer size is 8KB (for example when using 'dd
> > > if=/dev/sd0c of=/dev/null bs=131072' ) , Is there a reason for this?
> > > can this size be increased ?
> > I don't think there's any inherent limit in copyin/copyout. Physio is
> > a different story -- it doesn't use copyin/copyout at all.
> > >
> > >
> > > Thanks in advance
> > -- thorpej