On 02/22/2012 07:44 AM, Andreas Dilger wrote:

On 2012-02-20, at 12:00 AM, Tao Ma wrote:

quoted

Hi Ted, Andreas and list,
       This is the v4 attempt to add inline data support to ext4 inode.
For more information about the background, please refer to the thread
http://marc.info/?l=linux-ext4&m=131715205428067&w=2

Changlog from v3 to v4:
1. Add support for truncate which is really a bug.
2. Some bug fixes.
3. rebased to the latest kernel.

I'm starting to look through this patch series, and a number of things are

Thanks for the review.

missing that would make it much easier to understand and accept:
- a good comment and possibly a diagram at the start of fs/ext4/xattr.c
  that describes where and how the inline data is stored in the inode,
  what the policies are for storing data inline or externally, etc.

sure, I will add it.

- some benchmark data that shows why landing this code is desirable.
  My comments in the above thread show that small files and directories
  could benefit from this, but real proof now that you have made this
  patch is whether this translates into noticeable space savings, and
  hopefully also noticeable performance improvements in some benchmarks:
  - I suspect that running some tests with bigalloc + 512-byte inodes
    or similar could show significant space savings and speedups for
    cold-cache directory traversal
  - measuring boot time on a distro with Gnome or KDE could show real
    speedups due to the many small files and directories used at startup
  - running a benchmark like mongo or postmark with small files and
    with 256- or 512-byte inodes may also show real speedups
  - is there some workload that you are using that shows speedups that
    could be described in general terms and show relative performance,
    even if it is not possible to supply the actual benchmark/tests?

OK, I was just playing around with some bug fixes these days(to make it
stable in our production system) and doesn't do some performance tests
when upgrading from v2 to v3. I will try to do some tests and return the
data back in v5.

Thanks
Tao

I'll go through the patches and suggest cleanups and improvements, but
without improved documentation and real performance tests the patch is
very unlikely to be accepted by Ted.

quoted

Changelog from v2 to v3:
1. Add support for evict data from inode if we can store xattr in it.
2. Add support for fiemap
3. Some nasty bug fixes

The v3 can be found here:
http://marc.info/?l=linux-ext4&m=132421821001634&w=2

The v2 can be found here:
http://marc.info/?l=linux-ext4&m=132189338604177&w=2

The v1 can be found here:
http://marc.info/?l=linux-ext4&m=131961438221255&w=2

any suggestions are welcomed.

Thanks
Tao

Cheers, Andreas





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