application needs fast access to physical memory

[David Laight]

> On Wed, 2010-11-17 at 16:03 -0600, steven.lin at teradyne.com wrote:
> > My application needs a fast way to access a specific physical DDR
> > memory region. The application runs on an MPC8548 PowerPC which has
an
> > MMU. I've tried two approaches that are typical for Linux, mmap()
and
> > using a kernel module that implements read()/write() into this
region
> > and I'm finding that performance is very slow for both. It's a
couple
> > orders of magnitude slower than, for example, copying a large buffer
> > from one place in the application's virtual memory to another place
in
> > the application's virtual memory.
> 
> The mmap() version should basically run at "full speed", at least once
> you've faulted the address range in.
> 
> This specific DDR region isn't specifically slow is it ? :)

Or being mapped uncached ?

	David