Enhance ext2fs to support preallocation and read ext4 file systems

I have finished FreeBSD SoC 2010 this year. please review my own page in this site to review next works for ext2fs.

Abstract

During GSoC 2009, Aditya Sarawgi created a GPL-free implementation of ext2fs for FreeBSD, which has now been completed. The project is located in /head/sys/fs/ext2fs/. However the GPL-licensed preallocation code is removed.

This project implements preallocation in ext2fs and update ext2fs to be able to read ext4 file systems and possibly add other functionality, such as write ext4 file systems. The newer versions of ext2fs uses a reservation window mechanism. So this project will implement this mechanism.

Mentor

John Baldwin

Acknowledgement

Aditya Sarawgi

Pedro F. Giffuni

Schedule

This schedule do not determined and need to be reviewed by my mentor

References

Improving Second Extended File system (ext2fs) and making it GPL free (FreeBSD SoC 2009)

Ext4 (and Ext2/Ext3) Wiki

Design and Implementation of the Second Extended Filesystem

Benchmarking

I bought a new computer to run my benchmark. The computer has a Intel E5300 CPU, DDR2 800 2GB memory and a Hitachi 7200 RPM 250GB hard disk. I use ministat tool to calculate statistics data.

'ext2' is current implementation without preallocation. 'ext2+rsv(8)' is my implementation with reservation window, which the size of window is 8. 'ext2+rsv+dw' can dynamically increase the size of window. 'gpl' is a FreeBSD 8.0 implementation with preallocation.'ext2+rsv+dw w/ async' is mounted with 'async' mode.

mke2fs /dev/adX

mount -t ext2fs /dev/adX <mountpoint>

dbench

I run each benchmark 5 times because these benchmark need to run too long time. The measuring unit is MB/s.

dbench -D <mountpoint> <clientnumbers>

Thread 1:

x ext2
+ ext2+rsv
* ext2+rsv+dw
% gpl
# ext2+rsv+dw w/ async mode
    N           Min           Max        Median           Avg        Stddev
x   5       45.5045       51.5541       51.4006       49.9481     2.3945877
+   5       89.6299       91.4174       90.9006      90.57168    0.87129257
*   5       88.9354       91.7832       90.6713      90.32766     1.1425207
%   5        79.444       82.9166       81.1734      81.50848     1.4356841
#   5       104.619       108.499       107.003      106.9168     1.4420129

Thread 4:

x ext2
+ ext2+rsv
* ext2+rsv+dw
% gpl
# ext2+rsv+dw w/ async mode
    N           Min           Max        Median           Avg        Stddev
x   5       21.4515       26.2088       24.8431      24.13024      1.866238
+   5       29.2331       31.0921       30.1673      30.21956    0.71182337
*   5       27.5536       33.2609       31.2595       30.9399     2.2345179
%   5        26.941       29.3204       27.2857      27.96066     1.0999782
#   5       30.9833        43.039        41.071      39.40886     4.8328681

Thread 8:

x ext2
+ ext2+rsv
* ext2+rsv+dw
% gpl
# ext2+rsv+dw w/ async mode
    N           Min           Max        Median           Avg        Stddev
x   5       14.2031       15.3121       14.7745       14.7199    0.42417473
+   5       19.1683        21.509       20.9796      20.70498    0.90620942
*   5         19.86       20.7328       20.3172      20.34836    0.34299175
%   5       18.5462       20.3042       19.3613        19.422    0.71459646
#   5       20.5348        22.519       21.2898      21.42142    0.79828509

Thread 16:

x ext2
+ ext2+rsv
* ext2+rsv+dw
% gpl
# ext2+rsv+dw w/ async mode
    N           Min           Max        Median           Avg        Stddev
x   5       10.1522        10.996       10.6284      10.62836    0.31219525
+   5       12.8946       14.3441       13.5806      13.70512    0.60453204
*   5       13.7096       14.6223       14.2731      14.20036    0.33273137
%   5       12.8018       14.0892       13.2879      13.28362    0.50161008
#   5       16.2873       17.7242       17.2376      17.05444    0.65498857

20100628-dbench-result.png

Blogbench

I run each benchmark 10 times. This result is just a score. So it does't have a measuring unit.

blogbench -d <mountpoint>

Write score:

x ext2
+ ext2+rsv
* ext2+rsv+dw
% gpl
# ext2+rsv+dw w/ async
    N           Min           Max        Median           Avg        Stddev
x  10            29            39            33          32.9     3.0349812
+  10            36            43            37          38.3     2.7507575
*  10            35            44            38          38.2     2.9739611
%  10            31            44            35          35.4      4.376706
#  10            34            50            41          40.1     4.4334586

Read score:

x ext2
+ ext2+rsv
* ext2+rsv+dw
% gpl
# ext2+rsv+dw w async
    N           Min           Max        Median           Avg        Stddev
x  10         38714         67212         49050       49344.2     7644.3012
+  10         38435         60851         49903       48966.5     6510.8627
*  10         45062         68911         50454       51229.2     7278.6375
%  10         61553        100230         70331       73103.6     10791.084
#  10         41226         71295         52230       52605.1     8879.7999


Deprecated Implementation

NOTE: These benchmarks is only for reference.

Reason: The reservation window allocation hit is too low. When the number of threads are not too much (such as less than 4), most of allocation can hit in reservation window. However, When the number of threads are greater than 4, context switch get more frequently. hit ratio gets lower.

Platform

The computer has a Intel E5300 CPU, DDR2 800 2GB memory and a Hitachi 7200 RPM 250GB hard disk. I use ministat tool to calculate statistics data.

'ext2' is current implementation without preallocation. 'ext2+rsv(8)' is my implementation with reservation window, which the size of window is 8. 'ext2+rsv+dw' can dynamically increase the size of window.

dbench

I run each benchmark 5 times because these benchmark need to run too long time. The measuring unit is MB/s.

dbench -D <mountpoint> <clientnumbers>

Thread 1:

x ext2
+ ext2+rsv
* ext2+rsv+dw
    N           Min           Max        Median           Avg        Stddev
x   5       45.5045       51.5541       51.4006       49.9481     2.3945877
+   5       82.1763       89.3503       88.0009      86.92796     2.8524055
*   5       81.3983       89.4931       88.1687     86.946867     2.8929974

Thread 4:

x ext2
+ ext2+rsv
* ext2+rsv+dw
    N           Min           Max        Median           Avg        Stddev
x   5       21.4515       26.2088       24.8431      24.13024      1.866238
+   5       26.8594       31.9895       29.8409      29.80558     2.0533969
*   5       26.7923       30.9451       28.5845     28.818143     1.6385014

Thread 8:

x ext2
+ ext2+rsv
* ext2+rsv+dw
    N           Min           Max        Median           Avg        Stddev
x   5       14.2031       15.3121       14.7745       14.7199    0.42417473
+   5       17.3095       21.0776       20.4444      19.79332     1.5074286
*   5       17.6481       21.6323       19.8696      19.92342     1.7359695

Thread 16:

x ext2
+ ext2+rsv
* ext2+rsv+dw
    N           Min           Max        Median           Avg        Stddev
x   5       10.1522        10.996       10.6284      10.62836    0.31219525
+   5       10.5891       16.5768       14.2311     14.099983     1.9778735
*   5       10.8098       14.6764       14.0572     13.741214     1.3280996

20100604-dbench-result.png

Blogbench

I run each benchmark 10 times. This result is just a score. So it does't have a measuring unit.

blogbench -d <mountpoint>

Write score:

x ext2
+ ext2+rsv
* ext2+rsv+dw
    N           Min           Max        Median           Avg        Stddev
x  10            29            39            33          32.9     3.0349812
+  10            26            37            32            32     2.7633971
*  10            32            38            34          34.2     1.8593394

Read score:

x ext2
+ ext2+rsv
* ext2+rsv+dw
    N           Min           Max        Median           Avg        Stddev
x  10         38714         67212         49050       49344.2     7644.3012
+  10         38779         70237         45777      47869.25     8839.6211
*  10         42032         65169         46213       48610.4      6169.217


NOTE: This section is deprecated and it is just for reference.

Reason: These benchmark maybe doesn't reflect the real performance because I just run each benchmark three times and the platform is too old.

Platform

I conducted my all benchmarking on my notebook (I just can find this machine, which is idle). This notebook is IBM Thinkpad R51 with a 1.7GHz Intel Centrino CPU (It just have one core). It has a 1.25G DDR memory and a Hitachi 5400 RPM disk with a capacity of 60GB.

I run 3 times per benchmarking and calculate the average. 'ext2' is current implementation without preallocation. 'ext2+rsv(8)' is my implementation with reservation window, which the size of window is 8. 'ext2+rsv+dw' can dynamically increase the size of window.

uname -a
FreeBSD lz-freebsd 9.0-CURRENT FreeBSD 9.0-CURRENT #2: Fri May 28 17:31:21 CST 2010

Blogbench

blogbench -d <mountpoint>

r/w

ext2

ext2+rsv(8)

ext2+rsv+dw

writes

6.67

7.33 (10.0%)

7.67 (15.0%)

reads

70437.33

105083 (49.19%)

96844 (37.5%)

Dbench

dbench -D <mountpoint> <clientnumbers>

threads

ext2

ext2+rsv(8)

ext2+rsv+dw

1

33.9201

38.2006 (12.62%)

61.1552 (80.29%)

2

22.9775

22.8349 (-0.62%)

40.4392 (75.99%)

4

14.3622

15.1429 (5.43%)

16.934 (17.91%)

8

9.4165

10.9028 (15.78%)

12.0248 (27.70%)

16

6.4429

7.4228 (15.21%)

7.537835 (16.99%)


SOC2010ZhengLiu (last edited 2010-12-12 12:59:45 by ZhengLiu)