From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: [PATCH 3 of 8] xen: let the (credit) scheduler know
 about `node affinity`
Date: Tue, 09 Oct 2012 12:10:37 +0100
Message-ID: <CC99C4BD.412BA%keir.xen@gmail.com>
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To: Dario Faggioli <dario.faggioli@citrix.com>, Jan Beulich <JBeulich@suse.com>
Cc: Andre Przywara <andre.przywara@amd.com>, Ian Campbell <Ian.Campbell@citrix.com>, Marcus Granado <Marcus.Granado@eu.citrix.com>, George Dunlap <george.dunlap@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Juergen Gross <juergen.gross@ts.fujitsu.com>, Anil Madhavapeddy <anil@recoil.org>, Ian Jackson <Ian.Jackson@eu.citrix.com>, xen-devel@lists.xen.org, Matt Wilson <msw@amazon.com>, Daniel De Graaf <dgdegra@tycho.nsa.gov>
List-Id: xen-devel@lists.xenproject.org

On 09/10/2012 11:29, "Dario Faggioli" <dario.faggioli@citrix.com> wrote:

> On Fri, 2012-10-05 at 15:25 +0100, Jan Beulich wrote:
>>>>> On 05.10.12 at 16:08, Dario Faggioli <dario.faggioli@citrix.com> wrote:
>>> @@ -287,22 +344,26 @@ static inline void
>>>          }
>>>          else
>>>          {
>>> -            cpumask_t idle_mask;
>>> +            cpumask_t idle_mask, balance_mask;
>> 
>> Be _very_ careful about adding on-stack CPU mask variables
>> (also further below): each one of them grows the stack frame
>> by 512 bytes (when building for the current maximum of 4095
>> CPUs), which is generally too much; you may want to consider
>> pre-allocated scratch space instead.
>> 
> I see your point, and I think you're right... I wasn't "thinking that
> big". :-)
> 
> I'll look into all of these situations and see if I can move the masks
> off the stack. Any preference between global variables and members of
> one of the scheduler's data structures?

Since multiple instances of the scheduler can be active, across multiple cpu
pools, surely they have to be allocated in the per-scheduler-instance
structures? Or dynamically xmalloc'ed just in the scope they are needed.

 -- Keir

> Thanks and Regards,
> Dario