Re: [Xen-devel] [PATCH] xen: add hypercall option to temporarily pin a vcpu

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 26.02.16 at 14:07, <dario.faggioli@xxxxxxxxxx> wrote:
> On Fri, 2016-02-26 at 05:39 -0700, Jan Beulich wrote:
>> > > > On 26.02.16 at 12:20, <dario.faggioli@xxxxxxxxxx> wrote:
>> > On Fri, 2016-02-26 at 12:14 +0100, Juergen Gross wrote:
>> > > > Wouldn't it be even better to make this the "else" to the
>> > > > preceding if(), since in the suspend case this is otherwise
>> > > > going
>> > > > to be printed for every vCPU not currently running on pCPU0?
>> > > Yes, I'll change it.
>> > > 
>> > On this, can (either of) you elaborate a bit more? I don't think
>> > I'm
>> > following...
>> In addition to Jürgen's reply: My main concern here is that on
>> a bug system this message would get printed for almost every
>> vCPU in the system, which could end up being a lot of noise.
>> 
>> And there's a similar message on the resume side I think -
>> perhaps that one should be silenced too.
>> 
> What I don't understand is this part of your first comment "in the
> suspend case this is otherwise going to be printed for every vCPU not
> currently running on pCPU0".
> 
> First, do you mean with Juergen's patch, or even right now?

Even right now. Just that his patch made this pretty obvious.

> And anyway, this is going to be printed for all the vCPUs that does not
> have, in their hard affinity, any of the pCPUs that are going to remain
> online (or to remain in the domain's cpupool).
> 
> In shutdown and suspend, when we try to move everything to pCPU 0, it
> will get printed for all the vCPUs that does not have pCPU 0 in their
> hard affinity.
> 
> We can argue about that being useful or not, and about it being
> (potentially) too noisy or not. I personally think it could be useful
> (it's XENLOG_DEBUG, after all), but I won't oppose getting rid of it...
> I am just not getting why you're saying "not currently running on
> pCPU0".

Oh, you're right, that was too strict - "not being allowed to run
on CPU0" would be the right description. And indeed that makes
it look not as noisy (but too much, since during suspend this is
what one has to expect would happen).

Jan

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