Re: [PATCH v7]xen: sched: convert RTDS from time to event driven model

From: Meng Xu <mengxu@cis.upenn.edu>
To: Dario Faggioli <dario.faggioli@citrix.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	Tianyang Chen <tiche@seas.upenn.edu>,
	George Dunlap <george.dunlap@citrix.com>,
	Dagaen Golomb <dgolomb@seas.upenn.edu>
Subject: Re: [PATCH v7]xen: sched: convert RTDS from time to event driven model
Date: Thu, 10 Mar 2016 19:33:27 -0500	[thread overview]
Message-ID: <CAENZ-+=WawDE7trjxxKW48WVyit1iwQVYy-jRGVefm=YP_TFeg@mail.gmail.com> (raw)
In-Reply-To: <1457653986.3102.530.camel@citrix.com>

[My bad, Dario, I somehow only sent to you my reply... I'm resending
to everyone.]

On Thu, Mar 10, 2016 at 6:53 PM, Dario Faggioli
<dario.faggioli@citrix.com> wrote:
> On Thu, 2016-03-10 at 13:08 -0500, Meng Xu wrote:
>> On Thu, Mar 10, 2016 at 11:43 AM, Dario Faggioli
>> <dario.faggioli@citrix.com> wrote:
>> >
>> I think the pseudo-code makes sense. I just need to add some more
>> logic into it to make it complete. It forgets to handle the runq.
>>
> You mean...
>> >
>> >
>> >   ...
>> >   LIST_HEAD(tmp_replq);
>> >
>> >   list_for_each_safe(iter, tmp, replq)
>> >   {
>> >       svc = replq_elem(iter);
>> >
>> >       if ( now < svc->cur_deadline )
>> >           break;
>> >
>> >       list_del(&svc->replq_elem);
>> >       rt_update_deadline(now, svc);
>> >       list_add(&svc->replq_elem, &tmp_replq);
>>          /* if svc is on runq, we need to put it to the correct place
>> since its deadline changes. */
>>           if( __vcpu_on_q(svc) )
>>           {
>>               /* put back to runq */
>>              __q_remove(svc);
>>              __runq_insert(ops, svc);
>>
> ...This?

Yes.

>
> Well, sure, this was being done in repl_handler() in Tianyang's v7
> already, and I never meant to say we shouldn't do that any longer.
>
> I actually did not include it in here, because it was obvious to me
> that it still was necessary, and it was probably ok to put it in either
> of the loops (while I wanted to highlight what we need to do in the
> first and what in the second).
>
>> > It may look a bit convoluted, all these list moving, but I do like
>> > the
>> > fact that is is super self-contained.
>> >
>> > How does that sound / What did I forget this time ? :-)
>> Besides we need to "resort" the runq if the to-be-replenished vcpu is
>> on the runq now. Besides that, I think it's good.
>>
> If by re-sorting you mean what you added above, sure thing.
>

Yes. Since we have reached to some agreement on this, we can work on
the v8 now. :-D

Thanks and Best Regards,

Meng

-----------
Meng Xu
PhD Student in Computer and Information Science
University of Pennsylvania
http://www.cis.upenn.edu/~mengxu/

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