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From: Duncan <1i5t5.duncan@cox.net>
To: linux-btrfs@vger.kernel.org
Subject: Re: Snapshot aware defrag and qgroups thoughts
Date: Mon, 21 Apr 2014 22:13:11 +0000 (UTC)	[thread overview]
Message-ID: <pan$56a39$b0e4f3ef$30bd4a1b$c3f6fabf@cox.net> (raw)
In-Reply-To: 53553172.9030309@fb.com

Josef Bacik posted on Mon, 21 Apr 2014 07:55:46 -0700 as excerpted:

[Near the bottom, point #4 immediately before conclusion.]

> You still have to post-process merge to make sure, but you are far more
> likely to merge everything in real-time since you are only changing the
> sequence number every once and a while instead of for every new sequence
> number.

Much of this is above my head, which is OK as I'm not a btrfs dev, but...

...only changing the sequence number... for every new sequence number?

Something's wrong with that. No WONDER the system live-locked! =:^)

My above-my-head guess is that in place of for every new sequence number 
there, you meant for every delayed ref.

Meanwhile, thanks for putting this all down.  I already said I don't 
understand much of it, but I certainly have a better appreciation for the 
complexities of snapshot-aware-defrag.  I hadn't considered what qgroups 
could do to it at all!

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman


  reply	other threads:[~2014-04-21 22:13 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-21 14:55 Snapshot aware defrag and qgroups thoughts Josef Bacik
2014-04-21 22:13 ` Duncan [this message]
2014-06-19  9:46 ` Alex Lyakas

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