Subject: Re: Diamond RIO500 USB driver and tools ported.
To: Alex Nemirovsky <>
From: Thor Lancelot Simon <>
List: tech-kern
Date: 03/24/2000 12:34:44
On Fri, Mar 24, 2000 at 09:03:17AM -0800, Alex Nemirovsky wrote:
> However, I do have one concern that might make the use
> of the Linux userland tools undesireable.
> The speed of the driver/tools is not great. It takes
> about a minute to download a song. ~0.5 Mbits/sec.
> It is a full speed device however.
> Since the current driver is a character device I
> suspect the tools do alot
> of blocking and context switching passing data down
> from userland.  
> Is it possible or should we consider 
> making the driver into a block device instead?

Are you under the impression that "character device" means that data is
copied into the kernel or out to the device one character at a time?

That is not correct.

The difference between character and block devices is that block devices
are cached by the buffer cache.  If you're just blasting stuff at the
device as fast as you can, physio (which handles I/O for character devices)
is just as fast.