You are viewing a plain text version of this content. The canonical link for it is here.

Posted to user@mesos.apache.org by Sam Taha <ta...@gmail.com> on 2013/09/30 22:20:40 UTC

CPU resource requests

What does it mean to request fractiional CPU resources like 0.5 or 1.5. Is
this meaningful when making requests and how does it relate to isolation
levels. For example, you can't really pin 1.5 cores in a cgroup.

Should I really bother letting users/jobs request less than 1 cpu?

Thanks,
Sam Taha

http://www.grandlogic.com

Re: CPU resource requests

Posted by Sam Taha <ta...@gmail.com>.

Thanks Ben. That helps.


On Mon, Sep 30, 2013 at 9:10 PM, Benjamin Mahler
<be...@gmail.com>wrote:

> If using process isolation nothing is enforced.
>
> If using cgroups isolation:
>
>   with no subsystems: nothing is enforced.
>
>   with the 'cpu' subsystem: this will enforce your cgroup gets at least
> 0.5 cpu resources. Think of this as a lower bound guarantee on your cpu
> quota. You can use more if the system is otherwise idle.
>
>   with the 'cpu' subsystem and with --cgroups_enable_cfs: this will
> enforce your application gets at least 0.5 cpu resources and no more than
> 0.5 cpu resources. This adds an upper bound on your cpu consumption.
>
> So, fractions make sense and are definitely supported. Let me know if you
> need more clarification here.
>
> You may be interested in reading about cpu.shares:
>
> https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Resource_Management_Guide/sec-cpu.html
>
> Ben
>
>
> On Mon, Sep 30, 2013 at 1:20 PM, Sam Taha <ta...@gmail.com> wrote:
>
>> What does it mean to request fractiional CPU resources like 0.5 or 1.5.
>> Is this meaningful when making requests and how does it relate to isolation
>> levels. For example, you can't really pin 1.5 cores in a cgroup.
>>
>> Should I really bother letting users/jobs request less than 1 cpu?
>>
>> Thanks,
>> Sam Taha
>>
>> http://www.grandlogic.com
>>
>>
>>
>

Re: CPU resource requests

Posted by Benjamin Mahler <be...@gmail.com>.

If using process isolation nothing is enforced.

If using cgroups isolation:

  with no subsystems: nothing is enforced.

  with the 'cpu' subsystem: this will enforce your cgroup gets at least 0.5
cpu resources. Think of this as a lower bound guarantee on your cpu quota.
You can use more if the system is otherwise idle.

  with the 'cpu' subsystem and with --cgroups_enable_cfs: this will enforce
your application gets at least 0.5 cpu resources and no more than 0.5 cpu
resources. This adds an upper bound on your cpu consumption.

So, fractions make sense and are definitely supported. Let me know if you
need more clarification here.

You may be interested in reading about cpu.shares:
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Resource_Management_Guide/sec-cpu.html

Ben

On Mon, Sep 30, 2013 at 1:20 PM, Sam Taha <ta...@gmail.com> wrote:

> What does it mean to request fractiional CPU resources like 0.5 or 1.5. Is
> this meaningful when making requests and how does it relate to isolation
> levels. For example, you can't really pin 1.5 cores in a cgroup.
>
> Should I really bother letting users/jobs request less than 1 cpu?
>
> Thanks,
> Sam Taha
>
> http://www.grandlogic.com
>
>
>