[one-users] Nice & Priority control on disk access

[Ruben S. Montero]

Hi Carlos,

In your case the actual script used to do the cp is
/var/lib/one/remotes/tm/shared/clone.

Look for:

ssh_exec_and_log $DST_HOST \
                     "cd $DST_DIR; cp -r $SRC_PATH $DST_PATH" \
                     "Error copying $SRC to $DST"

This is the script executed at the remote node to cp the file. Just include
the ionice command befor the cp:

"ionice -c 3; cd $DST_DIR; cp -r $SRC_PATH $DST_PATH"

Note that:

1.- Any modification to the script must be distributed to the hosts with
onhost sync (you need to wait for a monitoring)

2.- If opennebula is reinstalled it'll overwrite your changes

3.- The command is executed as oneadmin, in case you need to setup sudos...

Cheers

Ruben





On Wed, Nov 14, 2012 at 11:17 AM, Carlos Jiménez <
cjimenez at eneotecnologia.com> wrote:

>  Thanks Ruben.
>
> I've realised that lower performance takes place each time a new VM is in
> PROLOG status or when I create/clone an image. I guess all that is related
> to disk access. As a testing purpose, I've cloned an image and executed
> iotop in the server where OpenNebula and NFS Server are running.
>
> This is a sample output:
>
>    PID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>
> COMMAND
>
>  3238 be/7 oneadmin 1783.88 K/s 1783.88 K/s  0.00 % 93.98 % cp -f
> /var/lib/one/datastores/1/9fedfe0d5cb02961~ne/datastores/1/72da3ba9d86fdc573b944c03253561ae
>
> Sometimes, there is another process (flush-147:0) with an important IO
> usage:
>    PID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>
> COMMAND
>
>  8028 be/4 root     1358.87 B/s    7.96 K/s  0.00 %  4.15 % [flush-147:0]
>
>
> How could I set an "ionice -c 3" to that "cp" command? I would like to do
> it in a global and persistent way so that future cp actions (due to
> creation or cloning of a VM or an image) have a lower ionice, not just once.
> Perhaps, I should set ionice in the driver configuration "exporting" a new
> global variable in /etc/one/defaultrc in the same way as the priority,
> shouldn't I? But, how do I configure ionice to interact with the proper
> driver?
>
>
> Thanks for your help.
>
> Carlos.
>
>
> On 11/13/2012 11:51 AM, Ruben S. Montero wrote:
>
> Hi
>
>  OpenNebula drivers are the piece of software that deals with the
> underlying subsystems. Each driver starts a new thread/process for each
> operation that should inherit the driver priority.
>
>  If you take a look to /etc/one/defaultrc, you can change the CPU
> priority assigned to the drivers. It defaults to 19, the least favorable to
> the process. You may want to try to use sets other io scheduling algorithm
> with ionice, or the blk module of cgroups.... or any other tool to adjust
> the I/O priority of a process.
>
>  Cheers
>
>  Ruben
>
>
>
>
> On Mon, Nov 12, 2012 at 5:59 PM, Carlos Jiménez <
> cjimenez at eneotecnologia.com> wrote:
>
>> Hi all,
>>
>> I have a server running OpenNebula 3.8 and acting as NFS server for
>> storaging with another host (running KVM and acting as a NFS client for the
>> storage). I have one VM running and then I try to create another VM using
>> Sunstone. Then, the running VM reduces its performance while the creation
>> of the new VM takes places. I guess OpenNebula I/O processes on the shared
>> disk have better priority/nice/ionice than disk access of the already
>> running VM.
>> The question is: Is there any way to control it so running VMs don't
>> decrease their performance? How do you reduce priority/nice/ionice of the
>> creation of the new VMs?
>>
>> Thanks in advance,
>>
>> Carlos.
>> _______________________________________________
>> Users mailing list
>> Users at lists.opennebula.org
>> http://lists.opennebula.org/listinfo.cgi/users-opennebula.org
>>
>
>
>
>  --
> Ruben S. Montero, PhD
> Project co-Lead and Chief Architect
> OpenNebula - The Open Source Solution for Data Center Virtualization
> www.OpenNebula.org | rsmontero at opennebula.org | @OpenNebula
>
>
>
> _______________________________________________
> Users mailing list
> Users at lists.opennebula.org
> http://lists.opennebula.org/listinfo.cgi/users-opennebula.org
>
>


-- 
Ruben S. Montero, PhD
Project co-Lead and Chief Architect
OpenNebula - The Open Source Solution for Data Center Virtualization
www.OpenNebula.org | rsmontero at opennebula.org | @OpenNebula
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