From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dario Faggioli <dario.faggioli@citrix.com>
Subject: Re: [PATCH 15/16] xen: sched: scratch space for
 cpumasks on Credit2
Date: Thu, 24 Mar 2016 14:10:34 +0100
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To: George Dunlap <george.dunlap@citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, xen-devel@lists.xenproject.org
Cc: George Dunlap <george.dunlap@eu.citrix.com>
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On Thu, 2016-03-24 at 12:44 +0000, George Dunlap wrote:
> On 18/03/16 19:27, Andrew Cooper wrote:
> > This avoids all this opencoded allocation/refcounting, the chance
> > that
> > starting a scheduler would fail for memory reasons, and one extra
> > cpumask in the per-cpu data area won't break the bank.
> Going a bit further, since (according to the changelog) both credit1
> and
> rtds also do this, would it make sense to have schedule.c define
> these,
> and allow any of the schedulers to use them?
>=20
Yeah, well, I guess it could.

> (Assuming that both credit1 and rtds allocate exactly one mask per
> cpu.)
>=20
They do.

The only difference between credit1 and the other two is that credit1
already has a per-cpu private scheduler structure (csched_pcpu, where
also the runqueue is), and the mask has been put there, so it's handled
a little bit differently.

But it should be no problem turning it into using a mask from
schedule.c, in the same way that RTDS and Credit2 will do.

I like the idea, and I'm up for it for v2.

Thanks and Regards,
Dario
--=20
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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