[Ocfs2-test-devel] [PATCH 0/8] Ocfs2-test: testing suite for defragmentation.

[Tristan Ye]

Hi All,
	After v3 online-defrag patches run into a relatively stable state, it
becomes a proper time to post v1 defrag testing suite which I used heavily during
kernel dev, the test currently mostly concentrated on the data verifications in
various senarios, benchmark testing may be taken into account later as in TO-DO list,
please take following description as a quick reference for performance boost:

1. Performance improvement gained on I/O reads:
-------------------------------------------------------------------------------
* Before defragmentation *

[root at ocfs2-box4 ~]# sync
[root at ocfs2-box4 ~]# echo 3>/proc/sys/vm/drop_caches 
[root at ocfs2-box4 ~]# time dd if=/storage/testfile-1 of=/dev/null
640000+0 records in
640000+0 records out
327680000 bytes (328 MB) copied, 19.9351 s, 16.4 MB/s

real	0m19.954s
user	0m0.246s
sys	0m1.111s

* Do defragmentation *

[root at ocfs2-box4 defrag]# ./defrag -s 0 -l 293601280  -t 3145728 /storage/testfile-1

* After defragmentation *

[root at ocfs2-box4 ~]# sync
[root at ocfs2-box4 ~]# echo 3>/proc/sys/vm/drop_caches
[root at ocfs2-box4 ~]# time dd if=/storage/testfile-1 of=/dev/null
640000+0 records in
640000+0 records out
327680000 bytes (328 MB) copied, 6.79885 s, 48.2 MB/s

real	0m6.969s
user	0m0.209s
sys	0m1.063s
-------------------------------------------------------------------------------


2. Extent tree layout via debugfs.ocfs2:
-------------------------------------------------------------------------------
* Before defragmentation *

        Tree Depth: 1   Count: 243   Next Free Rec: 8
        ## Offset        Clusters       Block#
        0  0             1173           86561
        1  1173          1173           84527
        2  2346          1151           81468
        3  3497          1173           76362
        4  4670          1173           74328
        5  5843          1172           66150
        6  7015          1460           70260
        7  8475          662            87680
        SubAlloc Bit: 1   SubAlloc Slot: 0
        Blknum: 86561   Next Leaf: 84527
        CRC32: abf06a6b   ECC: 44bc
        Tree Depth: 0   Count: 252   Next Free Rec: 252
        ## Offset        Clusters       Block#          Flags
        0  1             16             516104          0x0
        1  17            1              554632          0x0
        2  18            7              560144          0x0
        3  25            1              565960          0x0
        4  26            1              572632          0x
	...
	/* around 1700 extent records were hidden there */
	...
	138 9131          1              258968          0x0
        139 9132          1              259568          0x0
        140 9133          1              260168          0x0
        141 9134          1              260768          0x0
        142 9135          1              261368          0x0
        143 9136          1              261968          0x0

* After defragmentation *

      Tree Depth: 1   Count: 243   Next Free Rec: 1
	## Offset        Clusters       Block#
	0  0             9137           66081
	SubAlloc Bit: 1   SubAlloc Slot: 0
	Blknum: 66081   Next Leaf: 0
	CRC32: 22897d34   ECC: 0619
	Tree Depth: 0   Count: 252   Next Free Rec: 6
	## Offset        Clusters       Block#          Flags
	0  1             1600           4412936         0x0 
	1  1601          1595           20669448        0x0 
	2  3196          1600           9358856         0x0 
	3  4796          1404           14516232        0x0 
	4  6200          1600           21627400        0x0 
	5  7800          1337           7483400         0x0 
-------------------------------------------------------------------------------