From: Rolando Martins <rolando.martins@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: cgroup, RT reservation per core(s)?
Date: Tue, 3 Mar 2009 12:58:40 +0000 [thread overview]
Message-ID: <b6a2d2e20903030458o1c83a0f9ra52994e7a7f3be6c@mail.gmail.com> (raw)
In-Reply-To: <1234271177.23438.24.camel@twins>
On Tue, Feb 10, 2009 at 1:06 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Mon, 2009-02-09 at 20:04 +0000, Rolando Martins wrote:
>
>> I should have elaborated this more:
>>
>> root
>> ----|----
>> | |
>> (0.5 mem) 0 1 (100% rt, 0.5 mem)
>> ---------
>> | | |
>> 2 3 4 (33% rt for each group, 33% mem
>> per group(0.165))
>> Rol
>
>
> Right, i think this can be done.
>
> You would indeed need cpusets and sched-cgroups.
>
> Split the machine in 2 using cpusets.
>
> ___R___
> / \
> A B
>
> Where R is the root cpuset, and A and B are the siblings.
> Assign A one half the cpus, and B the other half.
> Disable load-balancing on R.
>
> Then using sched cgroups create the hierarchy
>
> ____1____
> / | \
> 2 3 4
>
> Where 1 can be the root group if you like.
>
> Assign 1 a utilization limit of 100%, and 2,3 and 4 a utilization limit
> of 33% each.
>
> Then place the tasks that get 100% cputime on your 2 cpus in cpuset A
> and sched group 1.
>
> Place your other tasks in B,{2-4} respectively.
>
> The reason this works is that bandwidth distribution is sched domain
> wide, and by disabling load-balancing on R, you split the schedule
> domain.
>
> I've never actually tried anything like this, let me know if it
> works ;-)
>
Just to confirm, cpuset.sched_load_balance doesn't work with RT, right?
You cannot have tasks for sub-domain 2 to utilize bandwidth of
sub-domain 3, right?
__1__
/ \
2 3
(50% rt) (50% rt )
For my application domain;) it would be interesting to have
rt_runtime_ns as a min. of allocated rt and not a max.
Ex. If an application of domain 2 needs to go up to 100% and domain 3
is idle, then it would be cool to let it utilize the full bandwidth.
(we also could have a hard upper limit in each sub-domain, like
hard_up=0.8, i.e. even if we could get 100%, we will only utilize
80%).
Does this make sense?
prev parent reply other threads:[~2009-03-03 12:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-09 19:30 cgroup, RT reservation per core(s)? Rolando Martins
2009-02-09 19:52 ` Peter Zijlstra
2009-02-09 20:04 ` Rolando Martins
2009-02-10 13:06 ` Peter Zijlstra
2009-02-10 14:46 ` Rolando Martins
2009-02-10 16:00 ` Peter Zijlstra
2009-02-10 17:32 ` Rolando Martins
2009-02-10 19:53 ` Peter Zijlstra
2009-02-11 11:33 ` Rolando Martins
2009-02-11 11:42 ` Peter Zijlstra
2009-02-11 11:53 ` Balbir Singh
2009-02-11 12:00 ` Peter Zijlstra
2009-02-11 12:10 ` Rolando Martins
2009-03-03 12:58 ` Rolando Martins [this message]
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