linux-ext4 - Re: [PATCH v4 0/15] ext4: add new online resize interface

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Date:	Sat, 19 Nov 2011 11:13:57 -0700
From:	Andreas Dilger <aedilger@...il.com>
To:	Yongqiang Yang <xiaoqiangnk@...il.com>
Cc:	"tytso@....edu" <tytso@....edu>,
	"adilger@...ger.ca" <adilger@...ger.ca>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH v4 0/15] ext4: add new online resize interface

On 2011-11-19, at 2:57, Yongqiang Yang <xiaoqiangnk@...il.com> wrote:
> This patch series adds new resize implementation to ext4.
> 
> -- What's new resize implementation?
>   It is a new online resize interface for ext4.  It can be used via
>   ioctl with EXT4_IOC_RESIZE_FS and a 64 bit integer indicating size
>   of the resized fs in block.
> 
> -- Difference between current resize and new resize.
>   New resize lets kernel do all work, like allocating bitmaps and
>   inode tables and can support flex_bg and BLOCK_UNINIT features.
>   Besides these, new resize is much faster than current resize.
> 
>   Below are benchmarks I made on my personal computer, fses with
>   flex_bg size = 16 were resized to 230GB evry time. The first
>   row shows the size of a fs from which the fs was resized to 230GB.
>   The datas were collected by 'time resize2fs'.
> 
>                      new resize
>                20GB          50GB      100GB
>      real    0m3.558s     0m2.891s    0m0.394s
>      user    0m0.004s     0m0.000s    0m0.394s
>      sys     0m0.048s     0m0.048s    0m0.028s
> 
>                      current resize
>                20GB          50GB      100GB
>      real    5m2.770s     4m43.757s  3m14.840s
>      user    0m0.040s     0m0.032s   0m0.024s
>      sys     0m0.464s     0m0.432s   0m0.324s

These stats must be backward, because resizing 20GB takes more time than resizing 100GB. 

>   According to data above, new resize is faster than current resize in both
>   user and sys time.  New resize performs well in sys time, because it
>   supports BLOCK_UNINIT and adds multi-groups each time.
> 
> -- About supporting new features.
>   YES! New resize can support new feature like bigalloc and exclude bitmap
>   easily.  Because it lets kernel do all work.
> 
> V3->V4:
>   rename __ext4_group_extend to ext4_group_extend_no_check.
> 
> V2->V3:
>   initialize block bitmap of last group.
>   remove code initalizing inode bitmap and inode tables.
> 
> Yongqiang.
> 
> git diff --stat
> 
> Documentation/filesystems/ext4.txt |    7 +
> fs/ext4/ext4.h                     |   10 +
> fs/ext4/ioctl.c                    |   39 ++
> fs/ext4/resize.c                   | 1167 +++++++++++++++++++++++++++---------
> 4 files changed, 942 insertions(+), 281 deletions(-)
> 
> 
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