Re: [Openstack] Openstack+KVM+overcommit, VM priority

[Adam Lawson]

With 4 physical cpu cores, you'll have 8 with HT so you likely don't need
anything managing overcommitting. But you also have memory contention in
your design. OpenStack facilitates resource limits to prevent the
contention from happening but does not get into managing vm priorities. The
assumption I presume is that high priority instances will be placed on high
priority hosts where overcommit ratios are safe for the VM's hosted on that
machine.

I know guys don't like to hear this when things are running but you need to
reassess what you're doing and rethink the 'why' factor to understand if
that level of manual management is really necessary. Remember this is a
cloud but your setup is basically complicated pet management. Add another
compute host and put your low priority instances on it rather than trying
to manage two SLA's yourself. Let OpenStack do it for you. ; )

//adam

All the best.

//adam

On Jan 12, 2017 9:17 AM, "Kostyantyn Volenbovskyi" <volenbov...@yandex.ru>
wrote:

Hi,

I have provided the answer to that on https://ask.openstack.org/en/
question/101374 where you asked this question as well.
That elaborates slightly on 'There are facilities to allow one VM or
another to have CPU priority’ which James mentioned below.
For RAM such things as Memory Tuning https://libvirt.org/formatdomain.html#
elementsMemoryTuning is not supported
as well as memory ballooning (which might be part of answer I think) are
not supported in Nova.
And well, ‘don’t overcommit RAM’ is often a good principle to stick to.


BR,
Konstantin
> On Jan 12, 2017, at 1:33 PM, Ivan Derbenev <ivan.derbe...@tech-corps.com>
wrote:
>
> What are the facilities for cpu? That's the initial question - how can I
do it if this is possible
>
>
> Best Regards
> Tech-corps IT Engineer
> Ivan Derbenev
> Phone: +79633431774
>
> -Original Message-
> From: James Downs [mailto:e...@egon.cc]
> Sent: Thursday, January 12, 2017 12:56 AM
> To: Ivan Derbenev <ivan.derbe...@tech-corps.com>
> Cc: openstack@lists.openstack.org
> Subject: Re: [Openstack] Openstack+KVM+overcommit, VM priority
>
> On Wed, Jan 11, 2017 at 09:34:32PM +, Ivan Derbenev wrote:
>
>> if both vms start using all 64gb memory, both of them start using swap
>
> Don't overcommit RAM.
>
>> So, the question is - is it possible to prioritize 1st vm above 2nd? so
the second one will fail before the 1st, to leave maximum possible
perfomance to the most importan one?
>
> Do you mean CPU prioritization? There are facilities to allow one VM or
another to have CPU priority, but what, if a high priority VM wants RAM,
you want to OOM the other? That doesn't exist, AFAIK.
>
> Cheers,
> -j
>
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Re: [Openstack] Openstack+KVM+overcommit, VM priority

[Adam Lawson]

This is a scheduler thing. Kvm/Linux has it's own scheduler built in for
any process that needs to share CPU cycles aside from the filter scheduler
used by OpenStack. My understanding is that any optimizations assigned to
resource consumption will not be handled by OpenStack but with manual
tweaks.

And I may be wrong about it not handled within nova. Also I know you're
doing it now but that is way against best practice my friend
(over-committing RAM).

//adam

On Jan 12, 2017 4:46 AM, "Ivan Derbenev" <ivan.derbe...@tech-corps.com>
wrote:

> What are the facilities for cpu? That's the initial question - how can I
> do it if this is possible
>
>
> Best Regards
> Tech-corps IT Engineer
> Ivan Derbenev
> Phone: +79633431774
>
> -Original Message-
> From: James Downs [mailto:e...@egon.cc]
> Sent: Thursday, January 12, 2017 12:56 AM
> To: Ivan Derbenev <ivan.derbe...@tech-corps.com>
> Cc: openstack@lists.openstack.org
> Subject: Re: [Openstack] Openstack+KVM+overcommit, VM priority
>
> On Wed, Jan 11, 2017 at 09:34:32PM +, Ivan Derbenev wrote:
>
> > if both vms start using all 64gb memory, both of them start using swap
>
> Don't overcommit RAM.
>
> > So, the question is - is it possible to prioritize 1st vm above 2nd? so
> the second one will fail before the 1st, to leave maximum possible
> perfomance to the most importan one?
>
> Do you mean CPU prioritization? There are facilities to allow one VM or
> another to have CPU priority, but what, if a high priority VM wants RAM,
> you want to OOM the other? That doesn't exist, AFAIK.
>
> Cheers,
> -j
>
> ___
> Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/
> openstack
> Post to : openstack@lists.openstack.org
> Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/
> openstack
>
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Re: [Openstack] Openstack+KVM+overcommit, VM priority

[Kostyantyn Volenbovskyi]

Hi, 

I have provided the answer to that on 
https://ask.openstack.org/en/question/101374 where you asked this question as 
well.
That elaborates slightly on 'There are facilities to allow one VM or another to 
have CPU priority’ which James mentioned below.
For RAM such things as Memory Tuning 
https://libvirt.org/formatdomain.html#elementsMemoryTuning is not supported
as well as memory ballooning (which might be part of answer I think) are not 
supported in Nova.
And well, ‘don’t overcommit RAM’ is often a good principle to stick to.


BR, 
Konstantin
> On Jan 12, 2017, at 1:33 PM, Ivan Derbenev <ivan.derbe...@tech-corps.com> 
> wrote:
> 
> What are the facilities for cpu? That's the initial question - how can I do 
> it if this is possible
> 
> 
> Best Regards
> Tech-corps IT Engineer
> Ivan Derbenev
> Phone: +79633431774
> 
> -Original Message-
> From: James Downs [mailto:e...@egon.cc] 
> Sent: Thursday, January 12, 2017 12:56 AM
> To: Ivan Derbenev <ivan.derbe...@tech-corps.com>
> Cc: openstack@lists.openstack.org
> Subject: Re: [Openstack] Openstack+KVM+overcommit, VM priority
> 
> On Wed, Jan 11, 2017 at 09:34:32PM +, Ivan Derbenev wrote:
> 
>> if both vms start using all 64gb memory, both of them start using swap
> 
> Don't overcommit RAM.
> 
>> So, the question is - is it possible to prioritize 1st vm above 2nd? so the 
>> second one will fail before the 1st, to leave maximum possible perfomance to 
>> the most importan one?
> 
> Do you mean CPU prioritization? There are facilities to allow one VM or 
> another to have CPU priority, but what, if a high priority VM wants RAM, you 
> want to OOM the other? That doesn't exist, AFAIK.
> 
> Cheers,
> -j
> 
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> Post to : openstack@lists.openstack.org
> Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack


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Re: [Openstack] Openstack+KVM+overcommit, VM priority

[Ivan Derbenev]

What are the facilities for cpu? That's the initial question - how can I do it 
if this is possible


Best Regards
Tech-corps IT Engineer
Ivan Derbenev
Phone: +79633431774

-Original Message-
From: James Downs [mailto:e...@egon.cc] 
Sent: Thursday, January 12, 2017 12:56 AM
To: Ivan Derbenev <ivan.derbe...@tech-corps.com>
Cc: openstack@lists.openstack.org
Subject: Re: [Openstack] Openstack+KVM+overcommit, VM priority

On Wed, Jan 11, 2017 at 09:34:32PM +, Ivan Derbenev wrote:

> if both vms start using all 64gb memory, both of them start using swap

Don't overcommit RAM.

> So, the question is - is it possible to prioritize 1st vm above 2nd? so the 
> second one will fail before the 1st, to leave maximum possible perfomance to 
> the most importan one?

Do you mean CPU prioritization? There are facilities to allow one VM or another 
to have CPU priority, but what, if a high priority VM wants RAM, you want to 
OOM the other? That doesn't exist, AFAIK.

Cheers,
-j

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Re: [Openstack] Openstack+KVM+overcommit, VM priority

[Ivan Derbenev]

no, that's not my question.

I'm already overcommiting, but now need to prioritize one instance above others 
in terms of perfomance.


От: Eugene Nikanorov <enikano...@mirantis.com>
Отправлено: 12 января 2017 г. 1:13:27
Кому: Ivan Derbenev; openstack@lists.openstack.org
Тема: Re: [Openstack] Openstack+KVM+overcommit, VM priority

Ivan,

see if it provides an answer: 
https://ask.openstack.org/en/question/55307/overcommitting-value-in-novaconf/

Regards,
Eugene.

On Wed, Jan 11, 2017 at 1:55 PM, James Downs 
<e...@egon.cc<mailto:e...@egon.cc>> wrote:
On Wed, Jan 11, 2017 at 09:34:32PM +, Ivan Derbenev wrote:

> if both vms start using all 64gb memory, both of them start using swap

Don't overcommit RAM.

> So, the question is - is it possible to prioritize 1st vm above 2nd? so the 
> second one will fail before the 1st, to leave maximum possible perfomance to 
> the most importan one?

Do you mean CPU prioritization? There are facilities to allow one VM or
another to have CPU priority, but what, if a high priority VM wants RAM,
you want to OOM the other? That doesn't exist, AFAIK.

Cheers,
-j

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Re: [Openstack] Openstack+KVM+overcommit, VM priority

[Eugene Nikanorov]

Ivan,

see if it provides an answer:
https://ask.openstack.org/en/question/55307/overcommitting-value-in-novaconf/

Regards,
Eugene.

On Wed, Jan 11, 2017 at 1:55 PM, James Downs  wrote:

> On Wed, Jan 11, 2017 at 09:34:32PM +, Ivan Derbenev wrote:
>
> > if both vms start using all 64gb memory, both of them start using swap
>
> Don't overcommit RAM.
>
> > So, the question is - is it possible to prioritize 1st vm above 2nd? so
> the second one will fail before the 1st, to leave maximum possible
> perfomance to the most importan one?
>
> Do you mean CPU prioritization? There are facilities to allow one VM or
> another to have CPU priority, but what, if a high priority VM wants RAM,
> you want to OOM the other? That doesn't exist, AFAIK.
>
> Cheers,
> -j
>
> ___
> Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/
> openstack
> Post to : openstack@lists.openstack.org
> Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/
> openstack
>
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Re: [Openstack] Openstack+KVM+overcommit, VM priority

[James Downs]

On Wed, Jan 11, 2017 at 09:34:32PM +, Ivan Derbenev wrote:

> if both vms start using all 64gb memory, both of them start using swap

Don't overcommit RAM.

> So, the question is - is it possible to prioritize 1st vm above 2nd? so the 
> second one will fail before the 1st, to leave maximum possible perfomance to 
> the most importan one?

Do you mean CPU prioritization? There are facilities to allow one VM or
another to have CPU priority, but what, if a high priority VM wants RAM,
you want to OOM the other? That doesn't exist, AFAIK.

Cheers,
-j

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