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 02:05:55
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 <firstname.lastname@example.org> 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