Re: [PATCH] xfs_db: defang frag command

Carlos Maiolino
2016-05-12T09:23:31Z

On Wed, May 11, 2016 at 02:41:28PM -0500, Eric Sandeen wrote:
> Too many people freak out about this fictitious "fragmentation
> factor." As shown in the fact, it is largely meaningless, because
> the number approaches 100% extremely quickly for just a few
> extents per file.
>
> I thought about removing it altogether, but perhaps a note
> about its uselessness, and a more soothing metric (avg extents
> per file) might be useful.
>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>
> diff --git a/db/frag.c b/db/frag.c
> index 36bb689..e11b140 100644
> --- a/db/frag.c
> +++ b/db/frag.c
> @@ -172,6 +172,10 @@ frag_f(
> answer = 0.0;
> dbprintf(_("actual %llu, ideal %llu, fragmentation factor %.2f%%\n"),
> extcount_actual, extcount_ideal, answer);
> + dbprintf(_("Note, this number is largely meaningless.\n"));
> + answer = (double)extcount_actual / (double)extcount_ideal;
> + dbprintf(_("Files on this filesystem average %.2f extents per file\n"),
> + answer);
> return 0;
> }

I'm not quite comfortable with it, in my mind, if it's meaningless, why should
we print it?

I agree with printing the average though.

>
>
>
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--
Carlos