I find that using LUKS results in a tremendous performance penalty:
156MB/s writes with LUKS v. 613MB/s without on a PCI-E SSD using ext4.
Am I failing to set up LUKS correctly? What can I do to improve
performance?
I am using kernel 2.6.36, 64bit userspace, and LUKS via cryptsetup 1.30
on a Q6600 w/ 4GB of RAM. I'm using bonnie++ for testing while the
machine is at idle. I made a volume group and logical volume (using
lvm2 v.2.02) on an 80gb OCZ revodrive, put LUKS on top of that, and then
did a naive ext4 format. Here is a record of my setup steps:
pvcreate /dev/mapper/sil_bgbiejcbajdj3
vgcreate Storage /dev/mapper/sil_bgbiejcbajdj3; lvcreate -l100%FREE -n
STORAGE Storage
cryptsetup luksFormat /dev/mapper/Storage-STORAGE
--key-file=/root/storage_tmp.key
cryptsetup luksOpen /dev/mapper/Storage-STORAGE local_storage
--key-file=/root/storage_tmp.key
mkfs.ext4 /dev/mapper/Storage-STORAGE
mount /dev/mapper/Storage-STORAGE /mnt/local_storage/; mkdir
/mnt/local_storage/file_perf; chown 87:87 /mnt/local_storage/file_perf
Here is the output from bonnie++ (bonnie++ -d
/mnt/local_storage/file_perf -f -r 4096 -u 87:87):
Version 1.96 ------Sequential Output------ --Sequential Input-
--Random-
Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
/sec %CP
h_ 4G 82203 11 46437 6 156632 9
+++++ +++
Latency 3175ms 2090ms 5362us
4344us
Version 1.96 ------Sequential Create------ --------Random
Create--------
h_ -Create-- --Read--- -Delete-- -Create-- --Read---
-Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
/sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
+++++ +++
Latency 106us 483us 625us 165us 78us
87us
... and the results with ext4 directly on the lv:
Version 1.96 ------Sequential Output------ --Sequential Input-
--Random-
Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
/sec %CP
h_ 4G 457214 66 202553 32 613262 34
+++++ +++
Latency 226ms 157ms 5418us
941us
Version 1.96 ------Sequential Create------ --------Random
Create--------
h_ -Create-- --Read--- -Delete-- -Create-- --Read---
-Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
/sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
+++++ +++
Latency 726us 530us 586us 113us 11us
46us
I notice similar degradation on a different storage system on the same
box. There I put 2 SAS 15K cheetahs in RAID0, created a vg and lv on
that, added LUKS, and formatted with XFS. With LUKS I got 127MB/s
writes, and without I got 215MB/s.
Am I misunderstanding something or somehow failing to configure this?
Do others experience this kind of performance hit? I thought at first
it could be explained by the overhead of performing crypto calculations,
but my processor's cores are quite underutilized during my tests. Any
help that can be offered is greatly appreciated: I use LUKS on 4 boxes
and all seem to suffer similarly. Finding a solution would be a big
help to me.
-mike dye
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