debian7 + script.sh

gistfile1.txt

BACKING=/dev/vdb
CACHE=/dev/vdc
sz=`sudo blockdev --getsz ${BACKING}`
echo $sz

sudo dd if=/dev/zero of=$CACHE oflag=direct bs=512 count=1
sudo dmsetup create wbdev --table "0 $sz writeboost $BACKING $CACHE 2 writeback_threshold 70"
sudo dmsetup status wbdev | wbstatus

sudo dd if=/dev/mapper/wbdev of=/tmp/o iflag=direct bs=4k count=1
sudo dmsetup status wbdev | wbstatus

sudo dd if=/dev/urandom of=/dev/mapper/wbdev oflag=direct bs=4k count=1
sudo dmsetup status wbdev | wbstatus


41943040
cursor pos              = 0
# of cache blocks       = 5201666
# of segments           = 40958
current id              = 1
last flushed id         = 0
last writeback id       = 0
# of dirty cache blocks = 0
# of partial flushes    = 0
write? hit? on_buffer? fullsize?
0      0    0          0         0
0      0    0          1         83
0      0    1          0         0
0      0    1          1         0
0      1    0          0         0
0      1    0          1         0
0      1    1          0         0
0      1    1          1         0
1      0    0          0         0
1      0    0          1         0
1      0    1          0         0
1      0    1          1         0
1      1    0          0         0
1      1    0          1         0
1      1    1          0         0
1      1    1          1         0
cursor pos              = 0
# of cache blocks       = 5201666
# of segments           = 40958
current id              = 1
last flushed id         = 0
last writeback id       = 0
# of dirty cache blocks = 0
# of partial flushes    = 0
write? hit? on_buffer? fullsize?
0      0    0          0         0
0      0    0          1         84
0      0    1          0         0
0      0    1          1         0
0      1    0          0         0
0      1    0          1         0
0      1    1          0         0
0      1    1          1         0
1      0    0          0         0
1      0    0          1         0
1      0    1          0         0
1      0    1          1         0
1      1    0          0         0
1      1    0          1         0
1      1    1          0         0
1      1    1          1         0
cursor pos              = 128
# of cache blocks       = 5201666
# of segments           = 40958
current id              = 2
last flushed id         = 1
last writeback id       = 0
# of dirty cache blocks = 1
# of partial flushes    = 0
write? hit? on_buffer? fullsize?
0      0    0          0         0
0      0    0          1         84
0      0    1          0         0
0      0    1          1         0
0      1    0          0         0
0      1    0          1         0
0      1    1          0         0
0      1    1          1         0
1      0    0          0         0
1      0    0          1         1
1      0    1          0         0
1      0    1          1         0
1      1    0          0         0
1      1    0          1         0
1      1    1          0         0
1      1    1          1         0