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Subject: Re: File copy system call proposal
Date: Sat, 8 Dec 2001 23:11:13 +0000 (UTC)
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From: linux-kernel@ton.iguana.be (Ton Hospel)
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In article <1007839431.371.0.camel@quinn.rcn.nmt.edu>,
	Quinn Harris <quinn@nmt.edu> writes:
> I wasn't aware of the sendfile system call.  But it apears that just
> like the mmap, write method suggested by H. Peter Anvin a memory copy is
> still performed when copying files from discs to duplicate the data for
> the buffer cache.  This would undoubtedly be faster than repeatedly
> calling read and write as it avoids one mem copy.  Yet GNU
> fileutils-4.1, that cp and install are part of, uses the read/write
> method.  I expect this is primarily because of portability issues but I
> wouldn't think the use of mmap would cause portability issues.

It does in fact. On some systems locks and mmaps are mutually exclusive.
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