[Bug 71641] Unreasonable performance degradation in ext4 with full data journaling

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=71641

Chia-Hung Chang <fredchang.tc@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Kernel Version|3.4.6                       |3.11

--- Comment #5 from Chia-Hung Chang <fredchang.tc@gmail.com> ---
(In reply to Theodore Tso from comment #4)
> Could you retry your measurements using the latest kernel?  At least 3.11,
> and preferably 3.13.
> 
> We significantly optimized the write path for the nodelalloc case in 3.11. 
> That should fix the average size being so small for the nodelalloc case:
> 
> 

Thanks for your advice. The kernel version is changed from 3.4 to 3.11.  The
write throughput of data=journal is still only 40% of data=order. Do you think
what may be wrong in this mode ?
---------------------

Test environment--  
CPU: Intel(R) Xeon(R) CPU E3-1225 v3 @ 3.20GHz
RAM:8GB
Filesystem:Ext4
Linux version: ubuntu-saucy with kernel 3.11

128MB ramdisk is used as journaling area

RAID0 are composed of 6 x 1TB HD
Command: time dd if=/dev/zero of= Write_File bs=1M count=5120


data=journal               -> 398MB/s
data=ordered               ->1.1GB/s
data=ordered ,nodelalloc   -> 1G/s

blktrace results can be downloaded in
https://dl.dropboxusercontent.com/u/32959539/blktrace_with_3_11.7z

btt results can be downloaded in
https://dl.dropboxusercontent.com/u/32959539/BTT_with_3_11.7z


For linux 3.4, the write throughputs are  

data=journal               -> 397MB/s
data=ordered               -> 937MB/s
data=ordered ,nodelalloc   -> 863MB/s*

*PS. the previous data is mistaken, please use this version.

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