From: Coly Li <i@coly.li>
To: Theodore Ts'o <tytso@mit.edu>
Cc: linux-ext4@vger.kernel.org
Subject: Re: [PATCH, RFC 00/12] bigalloc patchset
Date: Wed, 06 Apr 2011 01:23:19 +0800 [thread overview]
Message-ID: <4D9B5007.8050403@coly.li> (raw)
In-Reply-To: <1300570117-24048-1-git-send-email-tytso@mit.edu>
On 2011年03月20日 05:28, Theodore Ts'o Wrote:
> This is an initial patchset of the bigalloc patches to ext4. This patch
> adds support for clustered allocation, so that each bit in the ext4
> block allocation bitmap addresses a power of two number of blocks. For
> example, if the file system is mainly going to be storing large files in
> the 4-32 megabyte range, it might make sense to set a cluster size of 1
> megabyte. This means that each bit in the block allocaiton bitmap would
> now address 256 4k blocks, and it means that the size of the block
> bitmaps for a 2T file system shrinks from 64 megabytes to 256k. It also
> means that a block group addresses 32 gigabytes instead of 128
> megabytes, also shrinking the amount of file system overhead for
> metadata.
>
> The cost is increased disk space efficiency. Directories will consume
> 1T, as will extent tree blocks. (I am on the fence as to whether I
> should add complexity so that in the rare case that an inode needs more
> than 344 extents --- a highly fragmented file indeed --- and need a
> second extent tree block, we can avoid allocating any cluster and
> instead use another block from the cluster used by the inode. The
> concern is the amount of complexity this adds to the e2fsck, not just to
> the kernel.)
>
> To test these patches, I have used an *extremely* kludgy set of patches
> to e2fsprogs, which are attached below. These patches need *extensive*
> revision before I would consider them clean enough suitable for
> committing into e2fsprogs, but they were sufficient for me to do the
> kernel-side changes --- mke2fs, dumpe2fs, and debugfs work. E2fsck most
> definitely does _not_ work at this stage.
>
> Please comment! I do not intend for these patches to be merged during
> the 2.6.39 merge window. I am targetting 2.6.40, 3 months from now,
> since these patches are quite extensive.
Hi Ted,
Is it possible to open a git repo/branch for both kernel and user space tools ? So others can follow, help or provide
performance number in time :-)
Thanks.
Coly
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prev parent reply other threads:[~2011-04-05 16:54 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-19 21:28 [PATCH, RFC 00/12] bigalloc patchset Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 01/12] ext4: read-only support for bigalloc file systems Theodore Ts'o
2011-03-21 19:35 ` Lukas Czerner
2011-03-22 17:02 ` Ted Ts'o
2011-03-23 10:28 ` Lukas Czerner
2011-03-19 21:28 ` [PATCH, RFC 02/12] ext4: enforce bigalloc restrictions (e.g., no online resizing, etc.) Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 03/12] ext4: Convert instances of EXT4_BLOCKS_PER_GROUP to EXT4_CLUSTERS_PER_GROUP Theodore Ts'o
2011-03-20 10:26 ` Amir Goldstein
2011-03-21 13:12 ` Ted Ts'o
2011-03-19 21:28 ` [PATCH, RFC 04/12] ext4: Remove block bitmap initialization in ext4_new_inode() Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 05/12] ext4: factor out block group accounting into functions Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 06/12] ext4: split out ext4_free_blocks_after_init() Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 07/12] ext4: bigalloc changes to block bitmap initialization functions Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 08/12] ext4: Convert block group-relative offsets to use clusters Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 09/12] ext4: teach ext4_ext_map_blocks() about the bigalloc feature Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 10/12] ext4: teach ext4_statfs() to deal with clusters if bigalloc is enabled Theodore Ts'o
2011-03-21 20:17 ` Lukas Czerner
2011-03-22 22:09 ` Ted Ts'o
2011-03-19 21:28 ` [PATCH, RFC 11/12] ext4: tune mballoc's default group prealloc size for bigalloc file systems Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 12/12] ext4: enable mounting bigalloc as read/write Theodore Ts'o
2011-03-20 10:33 ` [PATCH, RFC 00/12] bigalloc patchset Amir Goldstein
2011-03-21 8:55 ` Andreas Dilger
2011-03-21 11:31 ` Rogier Wolff
2011-03-21 13:24 ` Ted Ts'o
2011-03-21 23:42 ` Andreas Dilger
2011-04-05 17:23 ` Coly Li [this message]
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