Gentoo Archives: gentoo-dev

From: Nirbheek Chauhan <nirbheek@g.o>
To: gentoo-dev@l.g.o
Cc: rich0@g.o
Subject: Re: [gentoo-dev] Re: proj/portage:master commit in: pym/portage/dbapi/
Date: Sat, 26 Nov 2011 15:59:47
Message-Id: CADqQcK4g_QaZK-VuK6D3Y5=S_5jVhEPo64XPGVx36=ZopMQHbA@mail.gmail.com
In Reply to: Re: [gentoo-dev] Re: proj/portage:master commit in: pym/portage/dbapi/ by "Michał Górny"
1 On Sat, Nov 26, 2011 at 8:39 PM, Michał Górny <mgorny@g.o> wrote:
2 > But in this particular case, I don't think COW is particularly useful.
3 > If it works only on filesystem bounds, we could move the file directly
4 > anyway.
5 >
6
7 There are still a few specific cases in which CoW would indeed be
8 useful. IIRC, reflinking of files works across btrfs *subvolumes*, and
9 such a copy would normally be detected as a cross-device move. Another
10 use would be an patch-merge which makes use of *ranged reflinks* to
11 only CoW copy those parts of the file that were changed[1]. rsync has
12 support for this, but only while appending to files (--append-verify
13 --no-whole-file).
14
15
16 1. Somewhat like rope data structures, with the caveat that ranges
17 must be block-size aligned.
18
19 --
20 ~Nirbheek Chauhan
21
22 Gentoo GNOME+Mozilla Team

Replies

Subject Author
Re: [gentoo-dev] Re: proj/portage:master commit in: pym/portage/dbapi/ "Michał Górny" <mgorny@g.o>