Online(inband) data deduplication

Hi Liu,

Thanks for your work.

Each test copy 2gb file from sdf (btrfs) to sde (btrfs with dedup 4k blocksize). Before every test i recreate filesystem.
On second write all goods.

Test 1
Nodesize = leafsize = 4k
Write overhead ~ x1.5

Test 2
Nodesize = leafsize = 16k
Write overhead ~ x19

Test 1:

fs created label (null) on /dev/sde

        nodesize 4096 leafsize 4096 sectorsize 4096 size 931.32GiB

Btrfs v3.14-dirty
./btrfs dedup enable /mnt/backupkvm/ ; ./btrfs dedup on -b4k /mnt/backupkvm/

[root@hranilka2 ~]# cat /sys/block/sde/stat
157149 3096 1285992 128900 6472058 12962342 718660664
1511294062 0 1576195 1527264468
[root@hranilka2 ~]# cat /sys/block/sde/stat
157149 3096 1285992 128900 6526802 13268740 724690168
1512117500 0 1587233 1528090320
write sectors: 724690168 - 718660664 = 6029504 sector write mbyte: 6029504 * 512 / 1024 / 1024 ~ 2944 mb

[root@hranilka2 ~]# cat /sys/block/sdf/stat
338633 165 346540680 7043771 7 4 1496 35
0 610795 7043095
[root@hranilka2 ~]# cat /sys/block/sdf/stat
342737 165 350743176 7127546 7 4 1496 35
0 618652 7126860
read sectors: 350743176 - 346540680 = 4202496 sector read mbyte: 4202496 * 512 / 1024 / 1024 ~ 2052 mb

Test 2:

fs created label (null) on /dev/sde

        nodesize 16384 leafsize 16384 sectorsize 4096 size 931.32GiB

Btrfs v3.14-dirty
./btrfs dedup enable /mnt/backupkvm/ ; ./btrfs dedup on -b4k /mnt/backupkvm/

[root@hranilka2 ~]# cat /sys/block/sde/stat
157440 3313 1290392 129277 6526912 13272046 724722864
1512117920 0 1587500 1528091116
[root@hranilka2 ~]# cat /sys/block/sde/stat
157440 3313 1290392 129277 6964494 13836479 803994376
1514935880 0 1730081 1530910351
write sectors: 803994376 - 724722864 = 79271512 sector write mbyte: 79271512 * 512 / 1024 / 1024 ~ 38706 mb

[root@hranilka2 ~]# cat /sys/block/sdf/stat
342737 165 350743176 7127546 7 4 1496 35
0 618652 7126860
[root@hranilka2 ~]# cat /sys/block/sdf/stat
346841 165 354945672 7266231 7 4 1496 35
0 629824 7265539
read sectors: 354945672 - 350743176 = 4202496 sector read mbyte: 4202496 * 512 / 1024 / 1024 ~ 2052 mb

--
Michael Serikov