From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1RUKfK-0001Hl-W5 for garchives@archives.gentoo.org; Sat, 26 Nov 2011 15:59:47 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id B484421C043; Sat, 26 Nov 2011 15:59:38 +0000 (UTC) Received: from mail-gy0-f181.google.com (mail-gy0-f181.google.com [209.85.160.181]) by pigeon.gentoo.org (Postfix) with ESMTP id B116F21C033 for ; Sat, 26 Nov 2011 15:59:12 +0000 (UTC) Received: by ghrr13 with SMTP id r13so5552827ghr.40 for ; Sat, 26 Nov 2011 07:59:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; bh=MyyyQe4LCoS4MHVQaz3tvGrTl1/BbiYqowlvxCsoilM=; b=h/zVf/pHxi3VygXFhhBUJ6r0KHWRaLOptWv3mjDD8J2y05Kap9tM2CGD7yVVKG5/n2 hAlXae7DiVrd+G2Oi/6D3lXjQE8t//nn/FbnOynkcMK1tmrJQ5zwoHsN0nnGXI7nl9co /ysGZjI+ZmJYGvc5HaJXYOFhpFY+HU9zljUic= Received: by 10.182.45.102 with SMTP id l6mr11174270obm.0.1322323152093; Sat, 26 Nov 2011 07:59:12 -0800 (PST) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-dev@lists.gentoo.org Reply-to: gentoo-dev@lists.gentoo.org MIME-Version: 1.0 Sender: nirbheek.chauhan@gmail.com Received: by 10.182.150.3 with HTTP; Sat, 26 Nov 2011 07:58:51 -0800 (PST) In-Reply-To: <20111126160936.64eeee1c@pomiocik.lan> References: <1d4ac47c28706094230cb2c4e6ee1c1c71629aa0.arfrever@gentoo> <20111126105822.GA37825@gentoo.org> <20111126113830.GC37825@gentoo.org> <20111126125915.428cb31a@googlemail.com> <20111126160936.64eeee1c@pomiocik.lan> From: Nirbheek Chauhan Date: Sat, 26 Nov 2011 21:28:51 +0530 X-Google-Sender-Auth: oPDsWN_b4Xs6eUyBsww7qnQ23Pg Message-ID: Subject: Re: [gentoo-dev] Re: proj/portage:master commit in: pym/portage/dbapi/ To: gentoo-dev@lists.gentoo.org Cc: rich0@gentoo.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Archives-Salt: 40403992-2c73-411f-93c2-c4930b8591df X-Archives-Hash: 23f990389f3c09e894680f8a46df5109 On Sat, Nov 26, 2011 at 8:39 PM, Micha=C5=82 G=C3=B3rny = wrote: > But in this particular case, I don't think COW is particularly useful. > If it works only on filesystem bounds, we could move the file directly > anyway. > There are still a few specific cases in which CoW would indeed be useful. IIRC, reflinking of files works across btrfs *subvolumes*, and such a copy would normally be detected as a cross-device move. Another use would be an patch-merge which makes use of *ranged reflinks* to only CoW copy those parts of the file that were changed[1]. rsync has support for this, but only while appending to files (--append-verify --no-whole-file). 1. Somewhat like rope data structures, with the caveat that ranges must be block-size aligned. --=20 ~Nirbheek Chauhan Gentoo GNOME+Mozilla Team