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From: "Garry T. Williams" <gtwilliams@gmail.com>
To: linux-btrfs@vger.kernel.org
Subject: Re: BTRFS setup advice for laptop performance ?
Date: Sat, 05 Apr 2014 10:26:06 -0400
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On 4-4-14 10:02:27 Swâmi Petaramesh wrote:
> However I'm still concerned with chronic BTRFS dreadful performance
> and still find that BRTFS degrades much over time even with periodic
> defrag and "best practices" etc.

Yeah, I have experienced this, too.  I can't say what your experience
was, but mine was all about copy-on-write along with two applications:
akonadi and Web browsers.

I no longer see the slow degradation over time because I made the
following directories recursively nodatacow:

    .local/share/akonadi
    .cache/google-chrome/Default
    .cache/mozilla/firefox/ogtorq5r.default

To do that, I had to copy[*] all of the existing files in those
hierarchies after chattr +C on the directories.

Using btrfs on my home directory has been fine ever since.



______________
[*] Examining my shell history turned up this snippet from that time:

    for i in 0 1 2 3;do
    mv data_$i data_$i.t
    touch data_$i
    chattr +C data_$i
    cp data_$i.t data_$i
    rm data_$i.t
    done

I carefully walked all the directories, while none of the applications
above were running, converting all of the files to +C.  It took a
while as I remember.  :-)

-- 
Garry T. Williams