From: Phillip Susi <psusi@ubuntu.com>
To: Theodore Ts'o <tytso@mit.edu>
Cc: Zheng Liu <gnehzuil.liu@gmail.com>,
linux-ext4@vger.kernel.org, Zheng Liu <wenqing.lz@taobao.com>
Subject: Re: [PATCH 3/3] mke2fs: document bigalloc and cluster-size
Date: Tue, 15 Jan 2013 14:46:17 -0500 [thread overview]
Message-ID: <50F5B209.40900@ubuntu.com> (raw)
In-Reply-To: <20130115191254.GD17719@thunk.org>
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On 1/15/2013 2:12 PM, Theodore Ts'o wrote:
> BTW, I used the following modified text:
>
> 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‐ tionally been known as the
> block allocation bitmap now indicates whether a cluster is in
> use or not, where a cluster is by default composed of 16 blocks.
> This feature can decrease the time spent on doing block
> allocation and brings smaller fragmentation, especially for
> large files. The size can be speci‐ fied using the -C option.
>
> Warning: The bigalloc feature is still under devel‐ 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?
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next prev parent reply other threads:[~2013-01-15 19:46 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-13 9:08 [PATCH 1/3] mke2fs: indicate bigalloc feature explicity when cluster-size is enabled Zheng Liu
2013-01-13 9:08 ` [PATCH 2/3] mke2fs: reduce the range of cluster-size Zheng Liu
2013-01-14 17:41 ` Andreas Dilger
2013-01-14 21:03 ` Theodore Ts'o
2013-01-14 21:07 ` Andreas Dilger
2013-01-14 21:10 ` Theodore Ts'o
2013-01-15 0:37 ` [PATCH 1/5] mke2fs: enforce that the cluster size must be less that the block size Theodore Ts'o
2013-01-15 0:37 ` [PATCH 2/5] mke2fs: the -g option will now specify the clusters per block group Theodore Ts'o
2013-01-15 15:10 ` Eric Sandeen
2013-01-15 19:05 ` Theodore Ts'o
2013-01-15 15:22 ` Zheng Liu
2013-01-15 0:37 ` [PATCH 3/5] libe2p: teach parse_num_blocks2() to return bytes if log_block_size < 0 Theodore Ts'o
2013-01-15 15:23 ` Zheng Liu
2013-01-15 0:37 ` [PATCH 4/5] mke2fs: teach mke2fs to understand -b 4k and -C 256M Theodore Ts'o
2013-01-15 15:11 ` Eric Sandeen
2013-01-15 15:13 ` Eric Sandeen
2013-01-15 15:24 ` Zheng Liu
2013-01-15 0:37 ` [PATCH 5/5] libext2fs: avoid 32-bit overflow in ext2fs_initialize with a 512M cluster size Theodore Ts'o
2013-01-15 15:33 ` Zheng Liu
2013-01-15 15:36 ` Zheng Liu
2013-01-15 19:10 ` Theodore Ts'o
2013-01-16 1:49 ` Zheng Liu
2013-01-15 0:41 ` [PATCH 1/5] mke2fs: enforce that the cluster size must be less that the block size Theodore Ts'o
2013-01-15 15:22 ` Zheng Liu
2013-01-13 9:08 ` [PATCH 3/3] mke2fs: document bigalloc and cluster-size Zheng Liu
2013-01-15 3:10 ` Theodore Ts'o
2013-01-15 19:12 ` Theodore Ts'o
2013-01-15 19:46 ` Phillip Susi [this message]
2013-01-15 19:57 ` Theodore Ts'o
2013-01-15 20:38 ` Phillip Susi
2013-01-15 22:28 ` Theodore Ts'o
2013-01-14 20:28 ` [PATCH 1/3] mke2fs: indicate bigalloc feature explicity when cluster-size is enabled Theodore Ts'o
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