Re: worse than expected compression ratios with -o compress

Gregory Maxwell
2010-01-21T20:04:56Z

On Thu, Jan 21, 2010 at 1:16 PM, Jim Faulkner <jfaulkne@ccs.neu.edu> wr=
ote:
>
> On Wed, 20 Jan 2010, Chris Mason wrote:
>
>> Please let me know if this improves your ratios
>
> It most certainly does! =C2=A0It also greatly reduced the time requir=
ed to copy
> the data to my (not very fast) disk. =C2=A0All my testing was done on=
2.6.32.4.
> The line numbers in your patch were a little off for 2.6.32.4, but I =
did
> manage to apply it cleanly. =C2=A0Here's the results of my testing:
[snip]
> I'd be very happy to see the -o compress-force option in the mainline=
kernel
> someday!

Sweet. But I think a force mount option is an unreasonably blunt tool.

I think two things would be nice:

(1) Fix the compression decision, I think this example suggests that
something is broken. (I'd noticed poorer than expected compression on
my laptop, but I'd chalked it up to the 64k blocks=E2=80=A6 now I'm not=
so
confident)

(2) An IOCTL for compression control. Userspace knows best, some
files ought to have a different compression policy.
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" =
in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html