Re: [PATCH v3] fallocate: Add "--dig-holes" option

[Rodrigo Campos <rodrigo@sdfg.com.ar>]

On Mon, Feb 17, 2014 at 11:32:48AM +0100, Karel Zak wrote:
> On Fri, Feb 14, 2014 at 11:47:56AM +0100, Karel Zak wrote:
> > On Sun, Jan 26, 2014 at 03:06:50PM +0000, Rodrigo Campos wrote:
> > >  bash-completion/fallocate |   2 +-
> > >  sys-utils/fallocate.1     |  19 +++++++-
> > >  sys-utils/fallocate.c     | 114 ++++++++++++++++++++++++++++++++++++++++------
> > >  3 files changed, 120 insertions(+), 15 deletions(-)
> > 
> >  Applied with some changes and I believe that the code still need some
> >  improvements, see below
> 
> 
>  OK, I did some changes to the code:
> 
>  The minimal hole size is based on filesystem blocksize (st_blksize) and 
>  --length is no more used for this thing. I think it's better to use

This was not updated in the manpage, where it shows the run modes. It still
says on the top "fallocate -d [-l length] filename"

>  buffer size which "just works" than expect any input from users. It
>  also dramatically simplify the code and the command semantic.

I looked at the code and this is probably too personal :)

> 
>  The original 32K is too large, I guess that we prefer optimal sparse
>  files rather than --dig-hole speed. (And it isn't so slow with 4KiB
>  chunks.)
> 
>  Now the --offset and --length options are used as usually to specify
>  an area with in the file.
> 
> 
> $ ls -lash yyy
> 1.1G -rw-rw-r-- 1 kzak kzak 1.0G Feb 17 11:09 yyy
> ^^^^
> 
> $ time ./fallocate --dig-holes yyy
> real    0m0.393s
> user    0m0.045s
> sys     0m0.345s
> 
> $ ls -lash yyy
> 28K -rw-rw-r-- 1 kzak kzak 1.0G Feb 17 11:10 yyy
> ^^^

How did you create the file ? With fallocate ? Is it all zeros ? If it's all
zeros, 28K used seems like a bug maybe ?

Any comparisson to see how much it took before (to see the improvement or the
slowdown) seems interesting. But, in any case, it doesn't seem *too* slow
(although 1GB is kind of a small file), and maybe is even faster :)


I can't test it in my new laptop because it fails to compile (autogen and
configure run fine). It throws:

	rm -f ca.gmo && : -c --statistics --verbose -o ca.gmo ca.po
	mv: cannot stat ‘t-ca.gmo’: No such file or directory
	make[3]: *** [ca.gmo] Error 1


is this a known issue ?





Thanks a lot,
Rodrigo