** Also affects: linux (Ubuntu Xenial)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1657281
Title:
Ubuntu xenial - 4.4.0-59-generic i3 I/O performance issue
Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Xenial:
New
Bug description:
[Impact]
* When running block device I/O on an Amazon i3 system there
is a performance degradation. A patch with git change id
87c279e613f848c691111b29 that is in Ubuntu-lts-4.8.0 kernel
series increases I/O performance.
* Fix should be backported to xenial 4.4 series to avoid more
support issues being filed.
* This change gets rid of uneccessary work being performed.
[Test Case]
* Steps to reproduce below
1) partition ephemeral disks
/sbin/parted -s --align optimal /dev/nvme0n1 mklabel gpt mkpart primary
0% 100%
/sbin/parted -s --align optimal /dev/nvme1n1 mklabel gpt mkpart primary
0% 100%
/sbin/parted -s --align optimal /dev/nvme2n1 mklabel gpt mkpart primary
0% 100%
/sbin/parted -s --align optimal /dev/nvme3n1 mklabel gpt mkpart primary
0% 100%
2) create raid array
/sbin/mdadm --create /dev/md0 --assume-clean --chunk=2048 --level=10
--raid-devices=4 /dev/nvme0n1p1 /dev/nvme1n1p1 /dev/nvme2n1p1 /dev/nvme3n1p1
3) create pv
/sbin/pvcreate --force --metadatasize 4092k /dev/md0
4) create volume group
/sbin/vgcreate RDSVG /dev/md0
5) create lv
/sbin/lvcreate -L 2.5T -n RDSRAIDLV RDSVG
5) test I/O
sudo dd if=/dev/zero of=/dev/RDSVG/RDSRAIDLV bs=8k count=1000000 && sync
[Regression Potential]
* No known regression potential.
[Original Description]
When we were doing testing on i3, we noticed that it is taking
significantly longer to perform operations when using software RAID
than without, we believe this is resolved in an upstream commit:
http://kernel.ubuntu.com/git/ubuntu/ubuntu-
xenial.git/commit/?id=87c279e613f848c691111b29d49de8df3f4f56da
So stock 4.4.0-59-generic performs ok:
$ sudo dd if=/dev/zero of=/dev/RDSVG/RDSRAIDLV bs=8k count=1000000 && sync
sudo: unable to resolve host ip-10-0-85-167
1000000+0 records in
1000000+0 records out
8192000000 bytes (8.2 GB, 7.6 GiB) copied, 54.3711 s, 151 MB/s
and the patch you originally providing works a little bit better (as
expected):
$ uname -a
Linux ip-10-0-85-167 4.4.0-57-generic
#78hf000000v20170110b0h3199a6e718db-Ubuntu SMP Tue Jan 10 02:53: x86_64 x86_64
x86_64 GNU/Linux
ubuntu@ip-10-0-85-167:~$ sudo dd if=/dev/zero of=/dev/RDSVG/RDSRAIDLV bs=8k
count=1000000 && sync
sudo: unable to resolve host ip-10-0-85-167
1000000+0 records in
1000000+0 records out
8192000000 bytes (8.2 GB, 7.6 GiB) copied, 31.4108 s, 261 MB/s
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