Re: better buffer size for copy

[Robert Latham]

(README says to ping if there's not been an ack of a patch after two
weeks.  here i go)

This patch to today's (18 Nov 2005) coreutils CVS makes copy.c
consider both the source and destination blocksize when computing
buf_size.  With this patch, src/copy.c will use the LCM of the soruce
and destination block sizes.  As Paul suggested, I used the buffer_lcm
routine from diffutils. 

For what it's worth, this patch does not introduce any regressions
into the coreutils testsuite.

When copying from a remote filesystem with a block size of 4MB to a
filesystem with a 4k blocksize, the copy is *very* slow.  Going from a
filesystem with 4k blocks to a filesystem with 4MB blocks is much
faster.  With this patch, both operations are equally performant.

I went ahead and added a ChangeLog entry as well.  

Thanks.  I'll be more than happy to incorporate any suggestions or
comments.

==rob


-- 
Rob Latham
Mathematics and Computer Science Division    A215 0178 EA2D B059 8CDF
Argonne National Labs, IL USA                B29D F333 664A 4280 315B

coreutils-lcm.patch
Description: Text document