Re: PATCH: Raw device IO for 2.1.131

Stephen Williams (steve@icarus.com)
Mon, 14 Dec 1998 11:07:57 -0800


alan@lxorguk.ukuu.org.uk said:
> Similarly scanners really want to be working direct scatter gather to
> big DMA buffers. Its fairly crazy to then go copying those to user
> space.

Yes, Yes, Yes! Thank you.

120 Pages/Minute Grayscale at 300DPI is adversely affected by memory copies.
(NT has similar problems.) However, I coerce Linux into providing the data
to the user without copying by allocating gobs of memory as a buffer and
making the application map that memory.

-- 
Steve Williams                "The woods are lovely, dark and deep.
steve@icarus.com              But I have promises to keep,
steve@picturel.com            and lines to code before I sleep,
http://www.picturel.com       And lines to code before I sleep."

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