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From: Gregory Maxwell <gmaxwell@gmail.com>
To: Jim Faulkner <jfaulkne@ccs.neu.edu>
Cc: Chris Mason <chris.mason@oracle.com>,
	Josef Bacik <josef@redhat.com>,
	linux-btrfs@vger.kernel.org
Subject: Re: worse than expected compression ratios with -o compress
Date: Thu, 21 Jan 2010 15:04:56 -0500	[thread overview]
Message-ID: <e692861c1001211204u7b16efe9tf7ee5703054caf76@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1001211224530.19136@alumni-linux.ccs.neu.edu>

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.
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  reply	other threads:[~2010-01-21 20:04 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-16 16:16 worse than expected compression ratios with -o compress Jim Faulkner
2010-01-17 14:34 ` Sander
2010-01-18 14:46   ` Jim Faulkner
2010-01-18 16:06     ` Jim Faulkner
2010-01-18 14:12 ` Josef Bacik
2010-01-18 21:29   ` Chris Mason
2010-01-18 22:11     ` Jim Faulkner
2010-01-20 16:30       ` Chris Mason
2010-01-21 18:16         ` Jim Faulkner
2010-01-21 20:04           ` Gregory Maxwell [this message]
2010-01-21 20:07             ` Chris Mason
2010-01-21 20:05           ` Chris Mason
2010-01-21 22:38             ` Jim Faulkner

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