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To: linux-kernel@vger.kernel.org
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: File copy system call proposal
Date: 7 Dec 2001 20:00:07 -0800
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Copyright: Copyright 2001 H. Peter Anvin - All Rights Reserved
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Followup to:  <1007782956.355.2.camel@quinn.rcn.nmt.edu>
By author:    Quinn Harris <quinn@nmt.edu>
In newsgroup: linux.dev.kernel
> 
> All kernel copy:
> Commands like cp and install open the source and destination file using
> the open sys call.  The data from the source is copied to the
> destination by repeatedly calling the read then write sys calls.  This
> process involves copying the data in the file from kernel memory space
> to the user memory space and back again.  Note that all this copying is
> done by the kernel upon calling read or write.  I would expect if this
> can be moved completely into the kernel no memory copy operations would
> be performed by the processor by using hardware DMA.
> 

mmap(source file);
write(target file, mmap region);

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>
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