user buffer question

hi

Can we use virtual memory or file mapping view buffer for device control and
read / write ? How can we send large data more than gigabytes to USB device
?

Thank for your teaching .

What is the max buffer size do you suggest ?


"Don Burn" wrote:

> Why would you want to have a gigabyte buffer? USB (even USB 3.0) is not
> fast enough to warrant this type of buffering. Your approach would
> consume significant system resources so slow down the whole computer. If
> this is a commercial product please let us know what company so we can
> boycott the firm offering it.
>
>
> Don Burn (MVP, Windows DKD)
> Windows Filesystem and Driver Consulting
> Website: http://www.windrvr.com
> Blog: http://msmvps.com/blogs/WinDrvr
>
>
>
> > -----Original Message-----
> > From: Kid [private.php?do=newpm&u=]
> > Posted At: Monday, July 05, 2010 12:23 AM
> > Posted To: microsoft.public.development.device.drivers
> > Conversation: user buffer question
> > Subject: user buffer question
> >
> > hi
> >
> > Can we use virtual memory or file mapping view buffer for device control
> > and
> > read / write ? How can we send large data more than gigabytes to USB
> > device
> > ?
> >
> > Thank for your teaching .
> >
> >
> > __________ Information from ESET Smart Security, version of virus
> > signature
> > database 5251 (20100704) __________
> >
> > The message was checked by ESET Smart Security.
> >
> > http://www.eset.com
> >
>
> .
>

Kid <> wrote:
>
>What is the max buffer size do you suggest ?

You need to do the math here. A gigabyte is going to take 20 or 25 seconds
to transfer, so there's no performance benefit in doing it as one big
transfer vs a whole bunch of smaller transfers. As long as the transfers
are multiples of 512 bytes, the device will see it as one big transfer.
--
Tim Roberts,
Providenza & Boekelheide, Inc.