touch-packages team mailing list archive

Thread
Date
[Bug 1346687] Re: Ubuntu 14 KVM Guest I/O Elevator Non-configurable

To: touch-packages@xxxxxxxxxxxxxxxxxxx
From: Dusan Baljevic <ubuntuadm@xxxxxxxxxxxxxxxxxxxx>
Date: Wed, 23 Jul 2014 00:47:24 -0000
Reply-to: Bug 1346687 <1346687@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx
Thank you for the update. I am then not sure why it is also "wrong" in
CentOS 7 guest. The inconsistency with other Linux distributions is what
I am concerned about...

# uname -a
Linux centos7-vm2 3.10.0-123.4.2.el7.x86_64 #1 SMP
Mon Jun 30 16:09:14 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

# cat /sys/block/vda/queue/scheduler 
noop [deadline] cfq 

# ./Linux-check-IO-scheduler-and-discard-support.pl 
INFO: File systems and raids
NAME                         FSTYPE      LABEL UUID                                   MOUNTPOINT
sr0                                                                                   
vda                                                                                   
├─vda1                       xfs               a1652174-58b6-4e97-a3ca-4a2160a31100   /boot
└─vda2                       LVM2_member       fVCpR3-mtm0-J1KU-XG56-IvOx-9Use-tqS0o2 
  ├─centos_centos7--vm2-swap swap              ad6f9fd9-59a5-49b2-afe9-531a8b74a446   [SWAP]
  └─centos_centos7--vm2-root xfs               63a2a109-cb5a-4b75-ac63-b903d81df633   /

INFO: Block devices
NAME                         ALIGNMENT MIN-IO OPT-IO PHY-SEC LOG-SEC ROTA SCHED    RQ-SIZE   RA WSAME
sr0                                  0    512      0     512     512    1 cfq          128  128    0B
vda                                  0    512      0     512     512    1 deadline     128 4096    0B
├─vda1                               0    512      0     512     512    1 deadline     128 4096    0B
└─vda2                               0    512      0     512     512    1 deadline     128 4096    0B
  ├─centos_centos7--vm2-swap         0    512      0     512     512    1              128 4096    0B
  └─centos_centos7--vm2-root         0    512      0     512     512    1              128 4096    0B

INFO: I/O elevator (scheduler) and discard support summary
INFO: Hard Disk vda configured with I/O scheduler "deadline"

All other KVM guests that I run exhibit different reports from Ubuntu
14.01:

OpenSUSE Linux 13.1 (3.11.10-17.x86_64 #1 SMP PREEMPT)

Oracle Linux 6.5 (3.8.13-35.1.2.el6uek.x86_64 #2 SMP)

CentOS Linux 7.0.1406 (3.10.0-123.4.2.el7.x86_64 #1 SMP)

Regards,

Dusan

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to util-linux in Ubuntu.
https://bugs.launchpad.net/bugs/1346687

Title:
  Ubuntu 14 KVM Guest I/O Elevator Non-configurable

Status in “util-linux” package in Ubuntu:
  Invalid

Bug description:
  Ubuntu 14.04 guest runs pretty much standard standard configuration:
  KVM hypervisor, ACPI and APIC enabled, virtio disk bus, raw storage
  format...

  While running this project, I am also involved in testing SSD drives
  across different Linux distributions and their support for discard
  option (TRIM).

  To cut the story short, Ubuntu-based KVM guest did not set any
  scheduler on the boot disk vda):

  # lsblk -io KNAME,TYPE,SCHED,ROTA,DISC-GRAN,DISC-MAX
  KNAME TYPE SCHED ROTA DISC-GRAN DISC-MAX
  sr0 rom deadline 1 0B 0B
  vda disk 1 0B 0B
  vda1 part 1 0B 0B
  vda2 part 1 0B 0B
  vda5 part 1 0B 0B
  dm-0 lvm 1 0B 0B
  dm-1 lvm 1 0B 0B

  That is in stark contrast with other distributions running almost
  identical KVM guest configuration (with the exception of the root file
  system using BTRFS instead of EXT4 on SUSE).

  Oracle Linux 6.5:

  # lsblk -io KNAME,TYPE,SCHED,ROTA,DISC-GRAN,DISC-MAX
  KNAME TYPE SCHED ROTA DISC-GRAN DISC-MAX
  sr0 rom deadline 1 0B 0B
  vda disk deadline 1 0B 0B
  vda1 part deadline 1 0B 0B
  vda2 part deadline 1 0B 0B
  dm-0 lvm 1 0B 0B
  dm-1 lvm 1 0B 0B

  OpenSUSE 13.1:

  # lsblk -io KNAME,TYPE,SCHED,ROTA,DISC-GRAN,DISC-MAX
  KNAME TYPE SCHED ROTA DISC-GRAN DISC-MAX
  sr0 rom cfq 1 0B 0B
  vda disk cfq 1 0B 0B
  vda1 part cfq 1 0B 0B
  vda2 part cfq 1 0B 0B
  dm-0 lvm 1 0B 0B
  dm-1 lvm 1 0B 0B

  Indeed, checking elevator capabilities for boot disk on Ubuntu KVM
  guest showed:

  # cat /sys/block/vda/queue/scheduler
  none

  Other Linux distributions show more options:

  # cat /sys/block/vda/queue/scheduler
  noop deadline [cfq]

  As well, attempts to change the elevator on Ubuntu guest fail. For
  example:

  # echo noop > /sys/block/vda/queue/scheduler

  # echo $?
  0

  # cat /sys/block/vda/queue/scheduler
  none

  Setting it globally in /etc/default/grub and updating it via update-
  grub2 fails too.

  In the meantime, to automate check of elevators (schedulers) and
  discard support for SSD drives and thin-provisioned volumes on Linux,
  I wrote simple Perl script:

  http://www.circlingcycle.com.au/Unix-sources/Linux-check-IO-scheduler-
  and-discard-support.pl.txt

  Part of the results on RHEL 6.5 server would look like:

  INFO: I/O elevator (scheduler) and discard support summary
  INFO: Hard Disk sdb configured with I/O scheduler "cfq"
  INFO: SSD sda configured with I/O scheduler "deadline" supports discard operation
  INFO: Hard Disk sdc configured with I/O scheduler "cfq"
  INFO: Hard Disk sdi configured with I/O scheduler "cfq"
  INFO: Hard Disk sdh configured with I/O scheduler "cfq"

  The Ubuntu KVM guest runs latest paches:

  Linux ubuntu14-vm2.circlingcycle.com.au 3.13.0-24-generic
  #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

  Regards,

  Dusan Baljevic VK2COT

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/1346687/+subscriptions