Hi,
I recently started using dm-thin module and first of all, thank you for the good work. It works great, well documented and the comments in the code are very useful. I tried to run some performance tests using a high performance flash device and the performance of dm thin is about 30% of LVM performance on a full allocated thin provisioned volume. ( ie after all pages/blocks are allocated using dd).
Performance test does only reads and no writes.
To reproduce the scenario easily, I tried same operations using ramdisk and dd.
To read 3.2G of data using dd,
Raw Ramdisk takes - 2.5 seconds
LVM Lun - takes 4 seconds
TP Lun ( after fully allocated) - takes 18 seconds
Steps involved
------------------
1. Linux 3.2.0.rc4 version from kernel.org
3.2.0-rc4 #1 SMP Fri Dec 16 13:25:02 EST 2011 x86_64 x86_64 x86_64 GNU/Linux
2. LVM2.2.02.88
3. compiling and installing dm thin modules.
4. Create a ramdisk of size 4G.
Ramdisk Raw Read Test
--------------------------
[root@lab-dm-cn4 ~]# dd
of=/dev/null if=/dev/ram bs=4096 count=786432
786432+0 records in
786432+0 records out
3221225472 bytes (3.2 GB) copied, 2.56607 s, 1.3 GB/s
LVM SETUP
------------------------
Create PV with 8M metadata on ramdisk , chunksize=8M in VG, lv uses 100%VG.
root@lab-dm-cn4 ~]# dd of=/dev/null if=/dev/6C067CWX00132-1/engineering bs=4096 count=$BLOCKS
786432+0 records in
786432+0 records out
3221225472 bytes (3.2 GB) copied, 4.06687 s, 792
MB/s
DM THIN SETUP
-----------------------
Create metadata device of size 8M and data device of size 3G using dm-linear on ramdisk.
Create TP Pool using the above devices with page/block size of 8M.
Create TP LUN in the TP Pool.
Using dd, write 4k to every page in the TP LUN so that all pages are allocated.
using "dmsetup status" verify that all pages in the pool are allocated.
[root@lab-dm-cn4 ~]# dd of=/dev/null if=/dev/mapper/thin1 bs=4096 count=$BLOCKS
786432+0 records in
786432+0
records out
3221225472 bytes (3.2 GB) copied, 18.2166 s, 177 MB/s
I have attached the output file and the script file used for this test. Any ideas / suggestions on what may be the bottle neck in dm-thin performance is much appreciated.
Thanks,
Jagan.
[root@lab-dm-cn4 ~]# #constants
[root@lab-dm-cn4 ~]# let ONEMEG=1024*2; #translated to sectors
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #user defined
[root@lab-dm-cn4 ~]# DMSETUP=/home/jagan/src/LVM2.2.02.88/tools/dmsetup
[root@lab-dm-cn4 ~]# LUN=1
[root@lab-dm-cn4 ~]# META_DEVICE_START_SECTOR=0 #on $DEVICE_PATH this is where meta data starts
[root@lab-dm-cn4 ~]# DEVICE_PATH=/dev/ram
[root@lab-dm-cn4 ~]# let META_DEV_SIZE=1*1024*$ONEMEG; #1G translated to sectors used in pvcreate command
[root@lab-dm-cn4 ~]# let PAGESIZE=8*$ONEMEG #page size is 8M in sectors
[root@lab-dm-cn4 ~]# let DATA_DEV_SIZE=3*1024*$ONEMEG+$PAGESIZE; #3G translated to sectors
[root@lab-dm-cn4 ~]# let LVM_DEVICE_SIZE=$META_DEV_SIZE+$DATA_DEV_SIZE;
[root@lab-dm-cn4 ~]# let DD_BS=4*1024 # dd block size = 4k bytes
[root@lab-dm-cn4 ~]# let BLOCKS=($DATA_DEV_SIZE-$PAGESIZE)*512/$DD_BS
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #system defined
[root@lab-dm-cn4 ~]# let DATA_DEVICE_START_SECTOR=$META_DEVICE_START_SECTOR+$META_DEV_SIZE
[root@lab-dm-cn4 ~]# let PAGES=$DATA_DEV_SIZE/$PAGESIZE
[root@lab-dm-cn4 ~]# let SEEK=$PAGESIZE*512/$DD_BS
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# echo $DMSETUP LUNID=$LUN DEVICE=$DEVICE_PATH DEVICE_START=$META_DEVICE_START_SECTOR META_DEV_SIZE=$META_DEV_SIZE DATA_DEV_SIZE=$DATA_DEV_SIZE PAGESIZE=$PAGESIZE DD_BS=$DD_BS DATA_DEVICE_START_SECTOR=$DATA_DEVICE_START_SECTOR PAGES=$PAGES SEEK=$SEEK BLOCKS=$BLOCKS LVM_DEVICE_SIZE=$LVM_DEVICE_SIZE
/home/jagan/src/LVM2.2.02.88/tools/dmsetup LUNID=1 DEVICE=/dev/ram DEVICE_START=0 META_DEV_SIZE=2097152 DATA_DEV_SIZE=6307840 PAGESIZE=16384 DD_BS=4096 DATA_DEVICE_START_SECTOR=2097152 PAGES=385 SEEK=2048 BLOCKS=786432 LVM_DEVICE_SIZE=8404992
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# pvcreate -M2 --dataalignment 4K --metadatacopies 1 --metadatasize 8M --zero y -v /dev/ram
Set up physical volume for "/dev/ram" with 8388608 available sectors
Zeroing start of device /dev/ram
Writing physical volume data to disk "/dev/ram"
Physical volume "/dev/ram" successfully created
[root@lab-dm-cn4 ~]# vgcreate -l 16384 -s 8M -c n -A n 6C067CWX00132-1 /dev/ram
WARNING: This metadata update is NOT backed up
Volume group "6C067CWX00132-1" successfully created
[root@lab-dm-cn4 ~]# lvcreate -A n -C n -l 100%VG -Z y -n engineering -r None 6C067CWX00132-1
WARNING: This metadata update is NOT backed up
WARNING: This metadata update is NOT backed up
Logical volume "engineering" created
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# # run dd test on several devices
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #write something
[root@lab-dm-cn4 ~]# dd if=/dev/zero of=/dev/6C067CWX00132-1/engineering bs=4096 count=$BLOCKS
786432+0 records in
786432+0 records out
3221225472 bytes (3.2 GB) copied, 4.63318 s, 695 MB/s
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #note the time on lvm device
[root@lab-dm-cn4 ~]# dd of=/dev/null if=/dev/6C067CWX00132-1/engineering bs=4096 count=$BLOCKS
786432+0 records in
786432+0 records out
3221225472 bytes (3.2 GB) copied, 4.06687 s, 792 MB/s
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# lvremove -f /dev/6C067CWX00132-1/engineering
Logical volume "engineering" successfully removed
[root@lab-dm-cn4 ~]# vgremove 6C067CWX00132-1
Volume group "6C067CWX00132-1" successfully removed
[root@lab-dm-cn4 ~]# pvremove /dev/ram
Labels on physical volume "/dev/ram" successfully wiped
[root@lab-dm-cn4 ~]# lvdisplay
No volume groups found
[root@lab-dm-cn4 ~]# vgdisplay
No volume groups found
[root@lab-dm-cn4 ~]# pvdisplay
[root@lab-dm-cn4 ~]# ls -l /dev/mapper
total 0
crw-rw----. 1 root root 10, 236 Jan 11 11:34 control
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #constants
[root@lab-dm-cn4 ~]# let ONEMEG=1024*2; #translated to sectors
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #user defined
[root@lab-dm-cn4 ~]# DMSETUP=/home/jagan/src/LVM2.2.02.88/tools/dmsetup
[root@lab-dm-cn4 ~]# LUN=1
[root@lab-dm-cn4 ~]# META_DEVICE_START_SECTOR=0 #on $DEVICE_PATH this is where meta data starts
[root@lab-dm-cn4 ~]# DEVICE_PATH=/dev/ram
[root@lab-dm-cn4 ~]# let META_DEV_SIZE=8*$ONEMEG; #8M translated to sectors
[root@lab-dm-cn4 ~]# let DATA_DEV_SIZE=3*1024*$ONEMEG; #3G translated to sectors
[root@lab-dm-cn4 ~]# let PAGESIZE=8*$ONEMEG #page size is 8M in sectors
[root@lab-dm-cn4 ~]# let DD_BS=4*1024 # dd block size = 4k bytes
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #system defined
[root@lab-dm-cn4 ~]# let DATA_DEVICE_START_SECTOR=$META_DEVICE_START_SECTOR+$META_DEV_SIZE
[root@lab-dm-cn4 ~]# let PAGES=$DATA_DEV_SIZE/$PAGESIZE
[root@lab-dm-cn4 ~]# let SEEK=$PAGESIZE*512/$DD_BS # how many blocks we need to seek in dd to go to next page
[root@lab-dm-cn4 ~]# let BLOCKS=$DATA_DEV_SIZE*512/$DD_BS
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# echo $DMSETUP LUNID=$LUN DEVICE=$DEVICE_PATH DEVICE_START=$META_DEVICE_START_SECTOR META_DEV_SIZE=$META_DEV_SIZE DATA_DEV_SIZE=$DATA_DEV_SIZE PAGESIZE=$PAGESIZE DD_BS=$DD_BS DATA_DEVICE_START_SECTOR=$DATA_DEVICE_START_SECTOR PAGES=$PAGES SEEK=$SEEK BLOCKS=$BLOCKS
/home/jagan/src/LVM2.2.02.88/tools/dmsetup LUNID=1 DEVICE=/dev/ram DEVICE_START=0 META_DEV_SIZE=16384 DATA_DEV_SIZE=6291456 PAGESIZE=16384 DD_BS=4096 DATA_DEVICE_START_SECTOR=16384 PAGES=384 SEEK=2048 BLOCKS=786432
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# echo 0 $META_DEV_SIZE linear $DEVICE_PATH $META_DEVICE_START_SECTOR | $DMSETUP create tp_meta_disk$LUN
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #zero out first 4k of meta data disk
[root@lab-dm-cn4 ~]# dd if=/dev/zero of=/dev/mapper/tp_meta_disk$LUN bs=4096 count=1
1+0 records in
1+0 records out
4096 bytes (4.1 kB) copied, 3.9319e-05 s, 104 MB/s
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #create data disk
[root@lab-dm-cn4 ~]# echo 0 $DATA_DEV_SIZE linear $DEVICE_PATH $DATA_DEVICE_START_SECTOR | $DMSETUP create tp_data_disk$LUN
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #create thin pool
[root@lab-dm-cn4 ~]# $DMSETUP create pool$LUN --table "0 $DATA_DEV_SIZE thin-pool /dev/mapper/tp_meta_disk$LUN /dev/mapper/tp_data_disk$LUN $PAGESIZE 0 " #1G page with 100 with no water mark
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #verify that 0 pages are allocated
[root@lab-dm-cn4 ~]# $DMSETUP status pool$LUN
0 6291456 thin-pool 0 9/2048 0/384 -
[root@lab-dm-cn4 ~]# $DMSETUP message /dev/mapper/pool$LUN 0 "create_thin 0"
[root@lab-dm-cn4 ~]# $DMSETUP create thin$LUN --table "0 $DATA_DEV_SIZE thin /dev/mapper/pool$LUN 0"
[root@lab-dm-cn4 ~]# #by now no pages should be allocated
[root@lab-dm-cn4 ~]# $DMSETUP status pool$LUN
0 6291456 thin-pool 0 10/2048 0/384 -
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #touch all pages on thin provisoned data disk so that all pages are allocated
[root@lab-dm-cn4 ~]# i=0;while [ $i -lt $PAGES ]; do let j=$i*$SEEK; echo $i; dd if=/dev/zero of=/dev/mapper/thin$LUN bs=4096 seek=$j count=1; let i=$i+1; done >&/dev/null
[root@lab-dm-cn4 ~]# #by now all pages should be allocated
[root@lab-dm-cn4 ~]# $DMSETUP status pool$LUN
0 6291456 thin-pool 0 18/2048 384/384 -
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #note the time on thin device
[root@lab-dm-cn4 ~]# dd of=/dev/null if=/dev/mapper/thin1 bs=4096 count=$BLOCKS
786432+0 records in
786432+0 records out
3221225472 bytes (3.2 GB) copied, 18.2166 s, 177 MB/s
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]#
[root@lab-dm-cn4 ~]# #cleanup
[root@lab-dm-cn4 ~]# $DMSETUP remove thin$LUN
[root@lab-dm-cn4 ~]# $DMSETUP message /dev/mapper/pool$LUN 0 "delete 0"
[root@lab-dm-cn4 ~]# $DMSETUP remove pool$LUN
[root@lab-dm-cn4 ~]# $DMSETUP remove tp_data_disk$LUN
[root@lab-dm-cn4 ~]# $DMSETUP remove tp_meta_disk$LUN
Attachment:
lvm_thin_compare.sh
Description: Bourne shell script
-- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
