Re: [PATCH v3 10/12] Btrfs-progs: add '--block-size' option to control print result

[Hugo Mills <hugo@carfax.org.uk>]

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On Wed, Oct 09, 2013 at 12:54:03AM +0800, Shilong Wang wrote:
> Hi David,
> 
> 2013/10/8 David Sterba <dsterba@suse.cz>:
> > On Mon, Oct 07, 2013 at 03:21:46PM +0800, Wang Shilong wrote:
> >> You can use it like:
> >>       btrfs qgroup show --block-size=m <mnt>
> >>
> >> Here, block size supports k/K/m/M/g/G/t/T/p/P/e/E.

k = SI prefix, kilo
K = ? (IEEE prefix kibi?)
m = SI prefix, milli
M = SI prefix, mega
g = SI unit, grams
G = SI prefix, giga
t = ?
T = SI prefix, tera
p = SI prefix, pico
P = SI prefix, peta
e = ?
E = SI prefix, exa

   Some confusion here, I think. :)

> > There is no distinction between the 1000 and 1024 based prefixes, also
> > no way to get the raw values in bytes. I don't have a suggestion how to
> > do that, merely letting you know that this could go separately (this and
> > the "-h" patch, the rest shall be integrated).
> 
> I implement this like the command 'du'.
> 
> In default, we print result in bytes. And block size don't give a byte
> unit implicitly.

> Aslo i don't know why we need to distinct 1000 and 1024, i don't
> have any ideas about this.

   Because when you have a terabyte of data, the difference between
the two is 10%. If you're putting in this kind of infrastructure, it's
not much of an addition to report in either SI decimal or IEEE binary
scales.

> > Also, the numbers in the table should be aligned to the right:
> 
> Yes, this should be fixed.
> 
> Thanks,
> Wang
> >
> > $ btrfs qgroup show -h -p /mnt/
> > qgroupid rfer      excl      parent
> > -------- ----      ----      ------
> > 0/5      900.00KiB 900.00KiB ---
> > 0/267    688.00KiB 12.00KiB  1/5
> > 0/268    684.00KiB 8.00KiB   1/5
> > 0/269    6.71GiB   4.00KiB   1/1
> > 0/277    6.71GiB   4.00KiB   1/1
> > 0/278    39.74GiB  39.74GiB  1/2
> > 1/1      6.71GiB   6.71GiB   ---
> > 1/2      39.74GiB  39.74GiB  ---
> > 1/5      696.00KiB 696.00KiB ---

   Note that the SI mandate a space between the value and the unit.
Note also, for future reference, that SI use k for 10^3, whereas IEEE
use Ki for 2^10.

   Hugo.

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
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