From: Phillip Susi Subject: Re: [PATCH 3/3] mke2fs: document bigalloc and cluster-size Date: Tue, 15 Jan 2013 14:46:17 -0500 Message-ID: <50F5B209.40900@ubuntu.com> References: <1358068095-9034-1-git-send-email-wenqing.lz@taobao.com> <1358068095-9034-3-git-send-email-wenqing.lz@taobao.com> <20130115031006.GB31857@thunk.org> <20130115191254.GD17719@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Zheng Liu , linux-ext4@vger.kernel.org, Zheng Liu To: Theodore Ts'o Return-path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120]:50908 "EHLO cdptpa-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751759Ab3AOTqT (ORCPT ); Tue, 15 Jan 2013 14:46:19 -0500 In-Reply-To: <20130115191254.GD17719@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 1/15/2013 2:12 PM, Theodore Ts'o wrote: > BTW, I used the following modified text: >=20 > bigalloc This feature enables clustered allocation, so that the > unit of allocation is a power of two number of blocks. That > is, each bit in the what had tradi=E2=80=90 tionally been known as t= he > block allocation bitmap now indicates whether a cluster is in > use or not, where a cluster is by default composed of 16 blocks.=20 > This feature can decrease the time spent on doing block > allocation and brings smaller fragmentation, especially for > large files. The size can be speci=E2=80=90 fied using the -C option= =2E >=20 > Warning: The bigalloc feature is still under devel=E2=80=90 opment, = and > may not be fully supported with your kernel or may have various > bugs. Please see the web page > http://ext4.wiki.kernel.org/index.php/Bigalloc for details. Does this mean that a cluster is the minimum allocation unit, or can two small files allocate different blocks in the same cluster, leaving the cluster partially used? If the former, then how is this different than just using a larger block size? -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (MingW32) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBAgAGBQJQ9bIJAAoJEJrBOlT6nu75WskIAM6eNjA1updKy6Kh2SrMWavB bX7EeTGmXMrxbQtMDgmG1+V2kOy9RoYtCZ5+pXijqJHzrovEtyIwHVdzntKSTtZi tYSqjZrOpJ/bTJpXuP5AIew9mXRTKzGF8lNyPZkLIgX0AyhTsbC4cccpcmfsnGEX RfuwDd2Z2NEKhmsXH4SI3HXDM2f4EGZmPqPG8It/B49HXrzfDq+YqzKwVqdrDJ5V jdTLV5xjJ4E9Y+/P3EC1l2KvfDf0KjJjA2CiuG4sqrthwwQGfdEFK+MF2bfz5nMi VBsuZQRF5kFgekpsHXy7b0Do9Qa3wMm9FL8Sv2QMy7xf92FxCwrLJFlpIZ9iuSQ=3D =3DBKGM -----END PGP SIGNATURE----- -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html